TMC428

TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 1 TMC428 – DATASHEET Intelligent Triple Stepper Motor Controller with Serial Peripheral Interfaces TRINAMIC Motion Control GmbH & Co. KG Sternstrasse 67 D – 20357 Hamburg GERMANY P +49 - (0) 40 - 51 48 06 - 0 F +49 - (0) 40 - 51 48 06 - 60 www.trinamic.com info@trinamic.com 1 Features The TMC428 is a miniaturized high performance stepper motor controller. It controls up to three 2phase stepper motors. All motors can operate independently. The TMC428 allows up to 6 bit micro step resolution – corresponding to 64 micro steps per full step – individually selectable for each motor. Once initialized, it performs all real time critical tasks autonomously based on target positions and velocities, which can be altered on-the-fly. So, an inexpensive microcontroller together with the TMC428 forms a complete motion control system. The microcontroller is free to do application specific interfacing and high level control functions. Both, the communication with the microcontroller and with one to three daisy chained stepper motor drivers take place via two separate 4 wire serial peripheral TM* interfaces. The TMC428 directly connects to SPI smart power stepper motor drivers. • • • • • • • • • • • • • • • • • • • Controls up to three 2-phase stepper motors Serial 4-wire interface for µC with easy-to-use protocol TM Configurable interface for SPI motor drivers TM Different types of SPI stepper motor driver chips may be mixed within a single daisy chain TM Communication on demand minimizes traffic to the SPI stepper motor driver chain TM Programmable SPI data rates up to 1 Mbit/s W ide range for clock frequency – can use CPU clock up to 16 MHz Internal 24 bit wide position counters Full step frequencies up to 20 kHz Read-out facility for actual motion parameters (position, velocity, acceleration) and driver status Individual micro step resolution of {64, 32, 16, 8, 4, 2, 1} micro steps via built-in sequencer Programmable 6 bit micro step table with up to 64 entries for a quarter sine-wave period Built-in ramp generators for autonomous positioning and speed control On-the-fly change of target motion parameters (like position, velocity, acceleration) Automatic acceleration dependent current control (power boost) Low power operation: Only 1.25 mA @ 4 MHz (typ.) Power down mode with transparent wake-up for normal operation 3.3V or 5V operation with CMOS / TTL compatible IOs (all inputs Schmitt-Trigger) Available in ultra small 16 pin SSOP package and small 24 pin SOP package * SPI is Trademark of Motorola, Inc. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 2 Life support policy TRINAMIC Motion Control GmbH & Co. KG does not authorize or warrant any of its products for use in life support systems, without the specific written consent of TRINAMIC Motion Control GmbH & Co. KG. Life support systems are equipment intended to support or sustain life, and whose failure to perform, when properly used in accordance with instructions provided, can be reasonably expected to result in personal injury or death. © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG Information given in this data sheet is believed to be accurate and reliable. However no responsibility is assumed for the consequences of its use nor for any infringement of patents or other rights of third parties which may result form its use. Specifications subject to change without notice. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 3 2 General Description The TMC428 is a miniaturized high performance stepper motor controller with a unique price / performance ratio for both, high volume automotive and for demanding industrial motion control applications. Once initialized, the TMC428 controls up to three 2-phase stepper motors. Its low price makes it attractive also for applications, where only one or two stepper motors have to be controlled simultaneously. The TMC428 performs all real time critical tasks autonomously. Thus a low cost microcontroller is sufficient to perform the tasks of initialization, application specific interfacing, and to specify target positions and velocities. The TMC428 allows on-the-fly change of all motion target parameters also during motion. Any other parameter may be changed at any time– also during motion –which does not make sense in any case, but this uniform access to any TMC428 register simplifies application programming. Read-back option for all internal registers simplifies programming. With its internal 23 position counters , the TMC428 can perform up to 2 steps respectively micro steps fully independent from the microcontroller. The step resolution– individually programmable for each stepper motor – ranges from full step (1 ‘’micro step’’ is one full step), half step (2 ‘’micro steps’’ per full step), up to 6 bit micro stepping (64 micro steps per full step) for precise positioning and noiseless stepper motor rotation (Table 8-8, page 26). Optionally, the micro step table– common for all motors –can be adapted to motor characteristics to further reduce torque ripple. The TMC428 has got serial interfaces for communication with the microcontroller and for the stepper motor drivers. The serial interface for the microcontroller uses a fixed length of 32 bits with a simple TM protocol, directly connecting to SPI interfaces. The serial interface to the stepper motor drivers is flexibly configurable for different types– even from different vendors –with up to 64 bit length for the SPI daisy chain. TRINAMIC smart power stepper motor drivers TMC236, TMC239 and TMC246, TMC249 perfectly fit to the TMC428. Without additional hardware, drivers with same serial interface polarities of chip select and clock signals may be mixed in a single chain. To mix drivers with different serial interface polarities, additional inverters (e.g. 74HC04, 74HC14) are required. For those driver chips without serial data output, two additional variants of the TMC428 with two additional chip select outputs are available. The TMC428 sends data to the driver chain on demand only, which minimizes the interface traffic and reduces the power consumption. Hint: Unused reference switch inputs should be pulled to ground (Figure 2-1). With this one can connect reference switches that connect to +5V resp. +3.3V when pushed. Concerning different reference switch configurations please refer to Figure 9-3, Figure 9-4, Figure 9-5. Reference Switch Inputs (active high) 1K 1K 1K *For details concerning electrical connections of the TMC236 / TMC239 / TMC246 / TMC249 refer to its datasheet. REF1 SS nSCS_C REF2 REF3 nSCS_S CSN * SDI SDO TMC23x / TMC24x SCK SCK_S MOSI µC SCK MISO CLK SDI_C TMC428-I / TMC428-A CLK V33 V5 TEST GND SDO_S CSN * SDI SDO TMC23x / TMC24x SCK CSN * SDI SDO TMC23x / TMC24x SCK SCK_C SDO_C SDI_S 470 nF Note: output SDO_C will nerver be high impedance +5 V 100 nF 10K SM#3 SM#2 SM#1 Figure 2-1: TMC428 application environment with TMC428 in SSOP16 package Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 4 REF1 REF2 REF3 nSCS3 nSCS2 SS nSCS_C nSCS_S MOSI µC SCK MISO CLK SDI_C TMC428-PI24 / TMC428-DI20 nSCS SDO_S SDI Driver w/o SDO SCK SDI nSCS Driver w/o SDO SCK SDI nSCS Driver w/o SDO SCK SDO SCK_C SDO_C CLK V33 V5 V5 TEST GND GND SCK_S SDI_S 470 nF 10K Note: output SDO_C will nerver be high impedance +5 V SM#3 SM#2 SM#1 Figure 2-2: Usage of drivers without serial data output (SDO) with TMC428 in larger packages (*the DI20 package variant is not recommended for new designs) 2.1 Step Frequencies TM The maximum SPI data rate is the clock frequency divided by 16. The maximum step frequency TM depends on the total length of the datagrams sent to the SPI stepper motor driver chain. At a clock TM frequency of 16 MHz, with a daisy chain of three SPI stepper motor drivers of 16 bit datagram length each, the maximum full step frequency is 16 MHz / 16 / ( 3 * 16 ). This is approximately 20 kHz and that is much higher than needed for typical stepper motors. But, the micro step rate may be higher, TM even if the stepper motor driver does not see all micro steps due to SPI data rate limit, as long as the number of skipped micro steps is less than a full step. In this respect, one should remember, that at high step rates– respectively pulse rates –the differences between micro stepping and full step excitation vanishes. 2.2 Modes of Motion The TMC428 has four different modes of motion, programmable individually for each stepper motor, named RAMPMODE, SOFTMODE, VELOCITYMODE, and HOLDMODE. For positioning applications the RAMPMODE is most suitable, whereas for constant velocity applications the VELOCITYMODE is. In RAMPMODE, the user just sets the position and the TMC428 calculates a trapezoidal velocity profile and drives autonomously to the target position. During motion, the position may be altered arbitrarily. The SOFTMODE is similar to the RAMPMODE, but the decrease of the velocity during deceleration is done with a soft, exponentially shaped velocity profile. In VELOCITYMODE, a target velocity is set by the user and the TMC428 takes into account user defined limits of velocity and acceleration. In HOLDMODE, the user sets target velocities, but the TMC428 ignores any limits of velocity and acceleration, to realize arbitrary velocity profiles, controlled completely by the user. The TMC428 has capabilities to generate interrupts depending on different stepper motor conditions chosen by an interrupt mask. However, status bits sent back automatically to the microcontroller each time it sends data to the TMC428 are sufficient for polling techniques. The TMC428 provides different modes for reference switch handling. In the default reference switch mode, the three reference switch inputs (REF1, REF2, REF3) are defined as left side reference st switches, one for each stepper motor. In another mode, the 1 reference input (REF1) is defined as left nd reference switch input of motor number one, the 2 reference input (REF2) is defined as left reference rd switch input of motor number two, and the 3 reference input (REF3) is defined as right reference switch of stepper motor number one. In that mode, there is no reference switch input available for stepper motor three. With an external multiplexer 74HC157 any stepper motor may have a left and a right reference switch. Many serial stepper motor drivers provide different status bits (driver active, inactive, ...) and error bits (short to ground, wire open, ...). To have access to those error bits, datagrams with a total length up to 48 bits sent back from the stepper motor driver chain to the TMC428 are buffered within two 24 bit wide registers. The microcontroller has direct access to these registers. Although, the TMC428 provides datagrams with up to 64 bits, only the last 48 bits sent back from the driver chain are buffered for read out by the microcontroller. This is because buffering of 3 times 16 bits is sufficient for a chain of three stepper motor drivers (see Figure 2-1, page 3) and most other drivers sending back up to 16 bits. For a chain of three TMC236 / TMC239 / TMC246 / TMC249 all status bits are accessible. From Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 5 the software point of view, the TMC428 provides a set of registers, accessed by a microcontroller (µC) via a serial interface in an uniform way. Each datagram contains address bits, a read-write selection bit, and data bits, to access the registers and the on-chip memory. Each time, the µC sends a datagram to the TMC428, it simultaneously receives a datagram from the TMC428. This simplifies the communication with the TMC428 and makes the programming easy. Most microcontrollers have an TM SPI hardware interface, which directly connects to the serial four wire microcontroller interface of the TM hardware, a software doing the serial communication is TMC428. For microcontrollers without SPI completely sufficient and can easily be implemented. 2.3 Notation of Number Systems & Notation of Two to the Power of n Decimal numbers are used as usual without additional identification. Binary numbers are identified by a prefixed % character. Hexadecimal numbers are identified by a prefixed $ character. So, for example the decimal number 42 in the decimal system is written as %101010 in the binary number system, and it is written as $2A in the hexadecimal number system. With this, TMC428 datagrams are written as 32 bit numbers (e.g. $1234ABCD = %00010010001101001010101111001101). In addition to the basic arithmetic operators (+, -, *, /) the operator two to the power of n is required at different sections of this n data sheet. For better readability instead of 2 the notation 2^n is used. 2.4 Signal Polarities Per default, signals– external and internal –are high active, but the polarity of some signals is programmable to be inverted. A pre-fixed lower case ‘n’ indicates low active signals (e.g. nSCS_C, nSCS_S). For example the polarity of nSCS_S can be inverted by programming, but also the polarity of datagram bits can be inverted by programming (see section 9, page 27). 2.5 Units of Motion Parameters Motion parameters position, velocity, and acceleration are given as integer values within TMC428 specific units. Section 8.14 page 26 explains, how to calculate steps, steps per second, steps per second square from given TMC428 integer values. With a given stepper motor resolution one can calculate physical units for angle, angular velocity, angular acceleration. 2.6 Representation of Signed Values by Two’s Complement Those motion parameters that have to cover negative and positive motion direction as well, are processed as signed numbers represented by two’s complement as usual. Signed motion parameters are x_target, x_actual, v_target, v_actual, a_actual. Limit motion parameters as v_min, v_max, a_max, a_threshold, are represented as unsigned binary numbers. 2.7 Tables of Contents A table of contents, a table of figures, and a table of tables are located at the end of the data sheet. 3 Package Variants The TMC428 is available in three different package variants, qualified for the industrial temperature range. An additional variant is available for the automotive temperature range. The package outlines and dimensions are included within this data sheet (page 45-47.) part number TMC428-I TMC428-A TMC428-PI24 TMC428-DI20 Package SSOP16 – 150 mils, 16 pins, plastic package, industrial (-40°C ... +85°C) SSOP16 – 150 mils, 16 pins, plastic package, automotive (-40°C ... +125°C) SOP24 – 300 mils, 24 pins, plastic package, industrial (-40°C ... +85°C) DIL20 – 300 mils, 20 pins, plastic package, industrial (-40°C ... +85°C) [This package variant is not recommended for new designs] JEDEC Drawing MO-137 (150 mils) MO-137 (150 mils) MS-013 (300 mils) MS-001 (300 mils) Table 3-1: TMC428 package variants Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 6 4 Pinning There are three package variants of the TMC428 available. The smaller SSOP16 package is sufficient for TRINAMIC stepper motor drivers (TMC236 / TMC239 / TMC246 / TMC249) with up to three drivers TM TM in a chain and for most SPI stepper motor drivers from other vendors. Some SPI stepper motor drivers from other vendors have no serial data output and can not simply be arranged in a daisy chain to drive more than one motor. The two package variants SOP24 and DIL20 have two additional driver selection outputs (nSCS2, nSCS3) for those stepper motor drivers without serial data output. All inputs are Schmitt-Trigger. Possibly unused inputs (REF1, REF2, REF3, SDI_S) need to be connected to ground. nSCS3 n.c. REF1 REF1 REF2 REF3 TEST CLK nSCS_C SCK_C SDI_C 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 SDI_S GND V33 V5 nSCS_S SCK_S SDO_S SDO_C REF2 REF3 V5 TEST CLK GND nSCS_C SCK_C SDI_C 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 n.c. V5 SDI_S GND V33 V5 nSCS3 nSCS2 REF1 nSCS_S SCK_S SDO_S REF3 SDO_C n.c. V5 TEST 9 10 REF2 7 8 SDI_S 5 6 V33 GND 3 4 1 2 20 19 18 17 16 15 14 13 12 11 nSCS2 nSCS_S SCK_S SDO_S SDO_C SDI_C SCK_C nSCS_C GND CLK TRINAMIC TRINAMIC SSOP16 (150 MILS) Figure 4-1: TMC428 pin out (*the DIL20 package variant is not recommended for new designs) TRINAMIC TMC 428-PI24 TMC 428-DI20 20 19 18 17 16 15 14 13 TMC428-I/A n.c. SOP24 (300 MILS) DIL20 (300 MILS) Pin Reset CLK nSCS_C SCK_C SDI_C SDO_C / nINT SSOP16 5 6 7 8 9 SOP24 7 9 10 11 14 DIL20* 11 13 14 15 16 In/Out I I I I O nSCS_S nSCS2 nSCS3 SCK_S SDO_S SDI_S REF1 REF2 REF3 V5 V33 GND TEST n.c. 12 11 10 16 1 2 3 13 14 15 4 - 17 18 19 16 15 23 2 3 4 5, 20 21 8, 22 6 1, 12, 13, 24 19 20 1 18 17 5 6 7 8 2, 9 3 4, 12 10 - O O O O O I I I I I - Description internal power-on reset clock input low active SPI chip select input driven from µC serial data clock input driven from µC serial data input driven from µC serial data output to µC input / multiplexed nINTERRUPT output if communication with µC is idle (resp. nSCS_C = 1) Important Note: SDO_C will never be high impedance, but this function can added with a single gate 74HCT1G125 (pls. refer Figure 4, page 9) SPI chip select signal to stepper motor driving chain SPI chip select signal (SOP24 & DIL20 package only) SPI chip select signal (SOP24 & DIL20 package only) serial data clock output to SPI stepper motor driver chain serial data output to SPI stepper motor driver chain serial data input from SPI stepper motor driver chain Note: pull-up/-down resistor at SDI_S avoids high impedance reference switch input 1 reference switch input 2 reference switch input 3 +5V supply / +3.3V supply 470 nF ceramic capacitor pin / +3.3V supply ground must be connected to GND as close as possible to the chip not connected Table 4-1: TMC428 pin out (*the DIL20 package variant is not recommended for new designs) Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 7 5 Functional Description and Block Diagram From the software point of view, the TMC428 provides a set of registers of different units and on-chip RAM (see Figure 5-1), accessed via the serial µC interface in an uniform way. The serial interface uses just a simple protocol with fixed length datagrams for read and write access. The serial interface to the stepper motor driver chain has to be configured by an initialization sequence which writes the configuration into the on-chip RAM. Once configured the serial driver interface works autonomously. The internal multiple port RAM controller of the TMC428 takes care of access scheduling. So, the user may read and write registers and on-chip RAM at any time. The registers hold global configuration parameters and the motion parameters. The on-chip RAM stores the configuration of the serial driver interface and the micro step table. The ramp generator monitors the motion parameters stored in its registers and calculates velocity profiles controlling the pulse generator. The pulse generator then generates step pulses taking into account user defined motion parameter limits. The serial driver interface sends datagrams to the stepper motor driver chain whenever a step pulse comes. The micro step unit (including sequencer) processes step pulses from the pulse generator– representing micro steps, half steps, or full steps depending on the selected step resolution –and makes the results available to the serial driver interface. The ramp generator also interfaces the reference switch inputs. Unused reference switches have to be connected to ground. A pull-down resistor is necessary at the SDI_S input of the TMC428 for those serial peripheral interface stepper motor drivers that set their serial data output to high impedance ‘Z’ while inactive. The interrupt controller continuously watches reference switches and ramp generator conditions and generates an interrupt if required. To save pins, the interrupt signal is multiplexed to the SDO_C signal. This output becomes the low active interrupt signal called nINT while nSCS_C is high (see Figure 6-1, page 8). So, if the microcontroller disables the interrupt during access to the TMC428 and enables the interrupt otherwise, the multiplexed interrupt output of the TMC428 behaves like a dedicated interrupt output. For polling, the TMC428 sends the status of the interrupt signal to the microcontroller with each datagram. To drive a stepper motor to a new target position, one just has to write the target position into the associated register by sending a datagram to the TMC428. To run a stepper motor with a target velocity, one just has to write the velocity into the register assigned to the stepper motor. REF3 REF2 REF1 interrupt controller [nSCS2] [nSCS3] nSCS_S SCK_S SDO_S SDI_S nSCS_C SCK_C SDI_C SDO_C serial µC interface ramp generator & pulse generator micro step unit ( including sequencer ) serial driver interface multiple ported RAM CLK 10K TEST power-on reset voltage regulator V5 V33 470nF GND Figure 5-1: TMC428 functional block diagram Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 8 6 Serial Peripheral Interfaces The four pins named SCS_C, SCK_C, SDI_C, SDO_C form the serial microcontroller interface of the TMC428. The communication between the microcontroller and the TMC428 takes place via 32 bit datagrams of fixed length. Concerning communication, the µC is the master and the TMC428 is the slave, with the TMC428 in turn being the master for the stepper motor driver daisy chain. Similar to the microcontroller interface, the TMC428 uses a four wire serial interface for communication with the stepper motor driver daisy chain. The four pins named SCS_S, SCK_S, SDO_S, SDI_S form the serial stepper motor driver interface. Stepper motor drivers with parallel inputs can be used in connection with the TMC428 with some additional glue logic. 6.1 Automatic Power-On Reset The TMC428 performs an automatic power-on reset. For details see section Power-On-Reset, page 50. The TMC428 cannot be accessed before the power-on-reset is completed and the clock is stable. All register bits are initialized with ‘0’ during power on reset, except the SPI clock pre-divider clk2_div (see section 9.7, page 29) that is initialized with 15. 6.2 Serial Peripheral Interface for µC The serial microcontroller interface of the TMC428 behaves as a simple 32 bit shift register. It shifts serial data SDI_C in with the rising edge of the clock signal SCK_C and copies the content of the 32 bit shift register with the rising edge of the selection signal nSCS_C into a buffer register. The serial interface of the TMC428 immediately sends back data read from registers or read from internal RAM via the signal SDO_C. The signal SDO_C can be sampled with the rising edge of SCK_C, but SDO_C becomes valid at least four CLK clock cycles after SCK_C becomes low as outlined in the timing diagram Figure 6-1. For detailed timing parameters see Table 6-1, page 10. The SPI signals from the µC interface may be asynchronous to the clock signal CLK of the TMC428. Because of on-the-fly processing of the input data stream, the serial microcontroller interface of the TMC428 requires the serial data clock signal SCK_C to have a minimum low / high time of three clock cycles. The data signal SDI_C driven by the microcontroller has to be valid at the rising edge of the serial data clock input SCK_C. The maximum duration of the serial data clock period is unlimited. While the µC interface of the TMC428 is idle, the SDO_C signal is the (active low) interrupt status nINT of the integrated interrupt controller of the TMC428. The timing of the multiplexed interrupt status signal nINT is characterized by the parameters tIS an tSI (see Table 6-1, page 10). Hint: If the microcontroller and the TMC428 work on different clock domains that run asynchronous to each other, the timing of the SPI interface of the microcontroller should be made conservative in the way that the length of one SPI clock cycle equals 8 or more clock cycles of the TMC428 clock CLK. This make the system robust concerning frequency drift, jitter, etc. tCLK tDATAGRAMuC tSUCSC tHDCSC tSCKCL tSCKCH tHDCSC tSUCSC CLK nSCS_C SCK_C SDI_C SDO_C nINT tIS 30 x sampled SDI_C 1 x SDI_C sampled one full 32 bit datagram 1 x SDI_C sampled tSD tSD tSD sdi_c_bit#31 sdi_c_bit#30 . . . sdi_c_bit#1 tPD sdi_c_bit#0 sdo_c_bit#0 tSI sdo_c_bit#31 sdo_c_bit#30 ... sdo_c_bit#1 nINT Figure 6-1: Timing diagram of the serial µC interface Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 9 A complete serial datagram frame has a fixed length of 32 bit. While the data transmission from the microcontroller to the TMC428 is idle, the low active serial chip select input nSCS_C and also the serial data clock signal SCK_C are set to high. While the signal nSCS_C is high, the TMC428 assigns the status of the internal low active interrupt signal named nINT to the serial data output SDO_C (see Figure 6-1). The serial data input SDI_C of the TMC428 has to be driven by the microcontroller. Important Hint: In contrast to most other SPI compatible devices, the SDO_C signal of the TMC428 is always driven. So, it will never be high impedance ‘Z’. If high impedance is required for the SDO_C connected to the microcontroller, it can simply be realized using a single gate 74HCT1G125. TM REF1 REF2 REF3 nSCS_S nSCS_C SDI_C SCK_C nSCS_C SDI_C SCK_C SCK_S TMC428 SDO_S SDOZ_C 74HCT1G125 SDO_C CLK V33 V5 TEST GND SDI_S Figure 4 : Making the TMC428 SDO_C output high impedance with single gate 74HCT1G125 The signal nSCS_C has to be high for at least three clock cycles before starting a datagram transmission. To initiate a transmission, the signal nSCS_C has to be set to low. Three clock cycles later the serial data clock may go low. The most significant bit (MSB) of a 32 bit wide datagram comes first and the least significant bit (LSB) is transmitted as the last one. A data transmission is finished by setting nSCS_C high three or more CLK cycles after the last rising SCK_C slope. So, nSCS_C and SCK_C change in opposite order from low to high at the end of a data transmission as these signals change from high to low at the beginning. The timing of the serial microcontroller interface is outlined in Figure 6-1. 6.3 Serial Peripheral Interface to Stepper Motor Driver Chain The timing of the serial stepper motor interface is similar to that of the microcontroller interface. It TM TM directly connects to SPI smart power stepper motor drivers. The SPI datagram is configurable individually for each stepper motor driver chip of the daisy chain. It is simply configurable by sending a fixed sequence of datagrams to the TMC428 to initialize it after power-up. Once initialized, the TMC428 autonomously generates the datagrams for the stepper motor driver daisy chain without any additional interventions of the microcontroller. The SPI datagram for each stepper motor driver is composed of so called primary signal bits provided by the micro step unit of the TMC428 individually for each stepper motor. Each primary signal bit is represented by a five bit code word called primary signal code. The order of primary signal bits TM forming the SPI datagrams for the stepper motor driver daisy chain is defined by the order of primary signal code words in the configuration RAM area. TM Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 10 tDATAGRAMdrv tCLK tPD tPD tPD m datagram bits CLK nSCS_S SCK_S SDO_S SDI_S tSUSCSdrv tHDSCSdrv sdo_s_bit#0 sdi_s_bit#0 tCKSL tCKSH sdo_s_bit#1 sdi_s_bit#1 sdo_s_bit#n-1 sdi_s_bit#n-1 sdo_s_bit#n sdi_s_bit#n 1 x sampled SDI_S m x sampled SDI_S one full stepper motor driver datagram 1 x sampled SDI_S Figure 6-3: Timing diagram of the serial stepper motor driver interface To switch to the next motor, an additional bit called next motor bit (NxM-Bit) is prefixed to the five bit wide primary signal code words. So, the total data word width is six bit. Each NxM-Bit effects an increment of an internal stepper motor address until the processing for all stepper motors within the daisy chain is completed. A parameter called LSMD (last stepper motor driver) defines the total number of stepper motors within the daisy chain. So, the codes written into the serial interface configuration RAM area represent the mapping of control signals provided by the micro step units to control bits of the drivers. It might be noted here, that configuring the serial driver interface is much easier as it might seem here. It is explained in detail, illustrated by examples below (see section 11 Stepper Motor Driver Datagram Configuration, page 36). Symbol tSUCSC tHDCSC tSCKCL tSCKCH tSD tIS tSI tDAMAGRAMuC tDAMAGRAMuC fCLK tCLK tPD Parameter Setup Clocks for nSCS_C Hold Clocks for nSCS_C Serial Clock Low Serial Clock High SDO_C valid after SCK_C low nINTERRUPT status valid after nSCS_C low SDO_C valid after nSCS_C high Datagram Length Datagram Length Clock Frequency Clock Period tCLK = 1 / fCLK CLK-rising-edge-to-Output Propagation Delay Min 3 3 3 3 2.5 2.5 3+3 + 32*6 = 198 12.375 0 62.5 Typ Max ∞ ∞ ∞ ∞ 3.5 4.5 ∞ ∞ 16 ∞ 5 Unit CLK periods CLK periods CLK periods CLK periods CLK periods CLK periods CLK periods CLK periods µs MHz ns ns Table 6-1: Timing characteristics of the serial microcontroller interface Symbol tSUSCSdrv tHDSCSdrv tCKSL tCKSH tDAMAGRAMdrv tDAMAGRAMdrv tPD Parameter Datagram Length Datagram Length @ fCLK = 16 MHz CLK-rising-edge to Outputs Delay Min 8 8 8 8 8+8+1*16+8+8=48 3 Typ 16 16 16 16 Max 256 256 256 256 512+64*512+512= 33792 2112 Unit CLK periods CLK periods CLK periods CLK periods CLK periods µs ns 5 Table 6-2: Timing characteristics of the serial stepper motor driver interface Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 11 The timing of the serial driver interface is programmable in a wide range. The clock divider provides 16 up to 512 clock cycles (tCLK) for a serial driver interface data clock period. The default duration of a clock period (tSCKCL+tSCKCH) of the signal nSCS_S is 16+16=32 clock periods of the clock signal CLK. The minimal duration of a serial interface clock period (tSCKCL+tSCKCH) is 8+8=16 clock cycles of signal CLK as outlined in Figure 6-3. Also, the polarities of the signals nSCS_S and SCK_S are programmable to use driver chips from other vendors with inverted polarities without additional glue logic. The input SDI_S of the serial driver interface must always be driven to a defined level. So, to avoid high impedance (‘Z’) at that input pin while the stepper motor driver chain is idle, a pull-up resistor or a pull-down resistor of 10 KΩ is required at that input. 6.4 Datagram Structure The microcontroller (µC) communicates with the TMC428 via the four wire (nSCS_C, SCK_C, SDI_C, SDO_C) serial interface. Each datagram sent to the TMC428 via the pin SDI_C and each datagram received from the TMC428 via the pin SDO_C is 32 bits long. The first bit sent is the MSB (most significant bit named sdi_c_bit#31 at Figure 6-1). The last bit sent is the LSB (least significant bit named sdi_c_bit#0 in Figure 6-1). During reception of a datagram, the TMC428 immediately sends back a datagram of the same length to the microcontroller. This datagram is the result of the request from the microcontroller. With each 32 bit wide datagram the microcontroller sends to the TMC428, it simultaneously receives a 32 bit wide datagram. A read request is distinguished from a write request by one datagram bit named RW. The TMC428 immediately sends back requested read data in the lower 24 datagram bits. Status bits are sent back in the higher 8 datagram bits. Datagrams sent from the microcontroller to the TMC428 have the form: MSB RRS ADDRESS LSB 32 bit DATAGRAM sent from µC to the TMC428 via pin SDI_C 33222222222211111111119876543210 1098765432109876543210 RW DATA Table 6-3 : 32 bit DATAGRAM structure sent from µC (MSB sent first) The 32 bit wide datagrams sent to the TMC428 are assorted in four groups of bits: RRS (register RAM select) selecting either registers or on-chip RAM; ADDRESS bits addressing memory within the register set or within the RAM area; RW (read / not write (RW=1 : read / RW=0 : write)) bit distinguishing between read access and write access; DATA bits for write access– for read access these bits are don’t care and should be set to ‘0‘. Different internal registers of the TMC428 have different lengths. So, for some registers only a subset of these 24 data bits is used. Unused data bits should be set to ‘0‘ for clearness. Some addresses select more than a single register mapped together into the 24 data bit space. The 32 bit wide datagrams received by the µC from the TMC428 contain two groups of bits: STATUS BITS and DATA BITS. The status bits, sent back with each datagram, carry the most important information about internal states of the TMC428 and the settings of the reference switches. These datagrams have the form: Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 12 MSB LSB 32 bit DATAGRAM sent back from the TMC428 to µC via pin SDO_C 33222222222211111111119876543210 1098765432109876543210 STATUS BITS DATA BITS SM3 SM2 SM1 xEQt1 RS1 xEQt2 RS2 xEQt3 RS3 CDGW INT Table 6-4: 32 bit DATAGRAM structure received by µC (MSB received first) The status bit INT is the internal high active interrupt controller status output signal. Handling of interrupt conditions without using interrupt techniques is possible by polling this status bit. The interrupt signal is also directly available at the SDO_C pin of the TMC428 if nSCS_C is high. The pin SDO_C may directly be connected to an interrupt input of the microcontroller. Since the SDO_C / nINT output is multiplexed, the microcontroller has to disable its interrupt input while it sends a datagram to the TMC428, because the SDO_C signal– driven by the TMC428 –alternates during datagram transmission. For initialization purposes, the TMC428 enables direct communication between the microcontroller and the stepper motor driver chain by sending a so called cover datagram (see sections 9.2 and 9.3). The position cover_position and actual length cover_len of a cover datagram is specified by writing them into a common register. Writing an up to 24 bit wide cover datagram to the register cover_datagram will fade in that cover datagram into the next datagram sent to the stepper motor driver chain. As a default setting, the TMC428 only sends datagrams on demand. Optionally, continuous update– periodic sending of datagrams to the stepper motor driver chain –is also possible. So, the status bit named CDGW (cover datagram waiting) is a handshake signal for the microcontroller in regard to the datagram covering mechanism. This feature is necessary to enable direct data transmission from a microcontroller to the stepper motor driver chips for initialization purposes. The CDGW status bit also gives the status of the datagram_high_word and datagram_low_word (see section 9.1). The status bits RS3, RS2, RS1 represent the settings of the reference switches. But, the reference switch inputs REF3, REF2, REF1 are not mapped directly to these status bits. Rather, the reference switch inputs may have different functions, depending on programming (see pages 22 - 24). The three status bits xEQt3, xEQt2, xEQt1 indicate individually for each stepper motor, if it has reached its target position. The status bits RS3, RS2, RS1 and bits xEQt3, xEQt2, xEQt1 can trigger an interrupt or enable simple polling techniques. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 13 6.5 Simple Datagram Examples The % prefix– normally indicating binary representation in this data sheet –is omitted for the following datagram examples. Assuming, one would like to write (RW=0) to a register (RRS=0) at the address %001101 the following data word %0000 0000 0000 0001 0010 0011, one would have to send the following 32 bit datagram 01100110000000000000000100100011 to the TMC428. With inactive interrupt (INT=0), no cover datagram waiting (CDGW=0), all reference switches inactive (RS3=0, RS2=0, RS1=0), and all stepper motors at target position (xEQt3=1, xEQt2=1, xEQt1=1) the status bits would be %10010101 the TMC428 would send back the 32 bit datagram: 10010101000000000000000000000000 To read (RW=1) back the register written before, one would have to send the 32 bit datagram 01100111000000000000000000000000 to the TMC428 and would get back from it the datagram 10010101000000000000000100100011. W rite (RW=0) access to on-chip RAM (RRS=1) to an address %111111 occurs similar to register access, but with RRS=1. To write two 6 bit data words %100001 and %100011 to successive pair-wise RAM addresses %1111110 and %1111111 (%100001 to %1111110 and %100011 to %1111111) which are commonly addressed by one datagram (see pages 14 and 35), one would have to send the datagram 11111110000000000010001100100001. To read (rw=1) from that on-chip memory address, one would have to send the datagram 11111111000000000000000000000000. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 14 7 Address Space Partitions The address space is partitioned in different ranges. Each of the up to three stepper motors has a set of registers individually assigned to it, arranged within a contiguous address space. An additional set of registers within the address space holds some global parameters common for all stepper motors. One dedicated global parameter register is essential for the configuration of the serial four wire stepper motor driver interface. One half of the on-chip RAM address space holds the configuration parameters for the stepper motor driver chain. The other half of the on-chip RAM address space is provided to store a micro step table if required. The first seven datagram bits (sdi_c_bit#31 and sdi_c_bit#30 ... sdi_c_bit#25, respectively RRS and ADDRESS) address the whole address space of the TMC428. address ranges (incl. RRS) %000 0000 . . . %000 1111 %001 0000 . . . %001 1111 %010 0000 . . . %010 1111 %011 0000 . . . %011 1110 %011 1111 %100 0000 . . . %101 1111 %110 0000 . . . %111 1111 assignment 16 registers for stepper motor #1 16 registers for stepper motor #2 16 registers for stepper motor #3 15 common registers 1 global parameter register 32 addresses of 2x6 bit for driver chain configuration 32 addresses of 2x6 bit for microstep table registers with up to 24 bits RAM 128x6 bit Table 7-1: TMC428 address space partitions The stepper motors are controlled directly by writing motion parameters into associated registers. Only one register write access is necessary to change a target motion parameter. E.g. to change the target position of one stepper motor, the microcontroller has to send only one 32 bit datagram to the TMC428. The same is true for changing a target velocity. Some parameters are packed together in a single data word at a single address. Those parameters– initialized once and unchanged during operation –have to be changed commonly. Access to on-chip RAM addresses concern two successive RAM addresses. So, always two data words are modified with each write access to the on-chip RAM. Once initialized after power-up, the content of the RAM is usually left unchanged. 7.1 Read and Write Read and write access is selected by the RW bit (sdi_c_bit#24) of the datagram sent from the µC to the TMC428. The on-chip configuration RAM and the registers are writeable with read-back option. Some addresses are read-only. Write access (RW=0) to some of those read-only registers triggers additional functions, explained in detail later. 7.2 Register Set The register address mapping is given in Table 7-2 on page 15. These registers are initialized internally during power-up. During power-up initialization, the TMC428 sends no datagrams to the stepper motor driver chain. Note: The RAM has to be initialized before writing target parameters to the register set. 7.3 RAM Area The RAM address mapping is given in Table 10-1 page 35. The on-chip RAM is NOT initialized internally during power-up. This has to be done by the microcontroller before operation. Note: There are unused addresses within the address space of the TMC428. Access to these addresses has no effect. How ever, access should be avoided, because this address space may be used for future devices. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 15 Important Hint: All register bits are initialized with ‘0’ during power on reset, except the SPI clock predivider clk2_div (see section 9.7, page 29) that is initialized with 15. 32 bit DATAGRAM sent from a µC to the TMC428 via pin SDI_C 33222222222211111111119876543210 1098765432109876543210 RRS RRS RW ADDRESS smda DATA three stepper motor register sets (SMDA={00, 01, 10}) x_target x_actual v_min v_max v_target v_actual a_max a_actual is_agtat is_aleat is_v0 a_threshold pdiv pmul 1 lp ref_conf rm interrupt_mask interrupt_flags pulse_div ramp_div usrs dx_ref_tolerance x_latched common registers (SMDA=11) datagram_low_word datagram_high_word cover_position cover_len cover_datagram power-down l3 r3 l2 r2 l1 r1 0 0 0 0 0 000 0 010 1 101 1 1 1 1 0 1 0 0 110 0 1 1 IDX 00 00 01 01 10 10 11 11 00 00 01 01 10 10 11 JDX 00 00 01 01 00 11 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0 1 0 1 0 0 RW=0 : WRITE access / RW=1 : READ access RW cw polarities cont_update nSCS_S SCK_S PH_AB FD_AB DAC_AB cs_ComInd refmux mot1r 111111 clk2_div LSMD ADDRESS DATA 33222222222211111111119876543210 1098765432109876543210 Table 7-2: TMC428 register address mapping Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 16 8 Register Description The registers hold binary coded numbers. Some are unsigned (positive) numbers, some are signed numbers in two’s complement, and some are control bits or single flags. The functionality of different registers depends on the ramp mode (s. page 22). 8.1 x_target (IDX=%0000) This register holds the current target position in units of full steps, respectively micro steps. The unit of the target position depends on the setting of the associated micro step resolution register usrs. If the difference x_target - x_actual is unequal zero, the TMC428 moves the stepper motor in that direction 23 of x_target so that the difference becomes zero. The condition | x_target - x_actual | < 2 must be satisfied for motion into the correct direction. Both, target position x_target and current position x_actual may be altered on the fly. Usually x_target is modified to start a positioning. To move from one position to another, the ramp generator of TMC428 automatically generates ramp profiles in consideration of the velocity limits v_min and v_max and acceleration limit a_max. Note: The registers x_target, x_actual, v_min, v_max, and a_max are initialized with zero after power up. Thus, no step pulses are generated because motion is prohibited. 8.2 x_actual (IDX=%0001) The current position of each stepper motor is available by read out of the registers called x_actual. The actual position can be overwritten by the microcontroller. This feature is for reference switch position calibration under control of the microcontroller. 8.3 v_min (IDX=%0010) This register holds the absolute value of the velocity at or below which the stepper motor can be stopped abruptly. The parameter v_min is relevant only for deceleration while reaching a target position. It should be set greater than zero. This control value allows to reach the target position faster because the stepper motor is not slowed down below v_min before the target is reached. Also consider, that due to the finite numerical representation of integral relations, the target position can not be reached exactly, if the calculated velocity is less than one, before the target is reached. So, setting v_min to at least one assures reaching each target position exactly. The unit of velocity parameters (v_max, v_target, and v_actual) is steps per time unit. The scale of velocity parameters (v_min, v_max, v_target, v_actual) is defined by the parameter pulse_div (see page 26 for details) and depends on the clock frequency of the TMC428. v(t) v_max ax _m -a a_ m ax -a a_ m ax ∆v ax _m ∆v v_min t t0 ∆t01 acceleration t1 constant velocity t2 deceleration t3 t4 t5 ∆t56 acceleration t6 deceleration t7 t8 Figure 8-1: Velocity ramp parameters and velocity profiles Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 17 8.4 v_max (IDX=%0011) This parameter sets the maximum motor velocity. The absolute value of the velocity will not exceed this limit, except if the limit v_max is changed during motion to a value below the current velocity. Note: To set target position x_target and current position x_actual to an equivalent value (e.g. to set both to zero at a reference point), the assigned stepper motor should be stopped first, and the parameter v_max should be set to zero to hold the assigned stepper motor at rest before writing into the register x_target and x_actual. 8.5 v_target (IDX=%0100) In modes RAMP_MODE and SOFT_MODE this register holds the current target velocity calculated internally by the ramp generator. In mode VELOCITY_MODE a target velocity can be written into this register. Then the associated stepper motor accelerates until it reaches the target velocity specified. In VELOCITY_MODE the velocity is changed according to the motion parameter limits if the register v_target is changed. In HOLD_MODE the register v_target is ignored. 8.6 v_actual (IDX=%0101) This read-only register holds the current velocity of the associated stepper motor. Internally, the ramp generator of the TMC428 processes with 20 bits while only 12 bits can be read out as v_actual. So, an actual velocity of zero read out by the microcontroller means that the current velocity is in an interval between zero and one. Because of this, the actual velocity should not be used to detect a stop of a stepper motor. For stop detection there is a dedicated bit within the interrupt register, which can simply be read out by the micro processor or generate an interrupt. Writing zero to register v_actual, which is possible in HOLD_MODE only, immediately stops the associated stepper motor, because hidden bits are set to zero with each write access to the register v_actual. In HOLD_MODE only, this register is a read-write register. In HOLD_MODE, motion parameters are ignored and the microcontroller has the full control to generate a ramp. In that mode, the TMC428 only handles the microstepping and datagram generation for the associated stepper motor of the daisy chain. 8.7 a_max (IDX=%0110) The absolute value of the maximum acceleration is defined by this register. It ranges from 0 to 2047. The unit of the acceleration is change of step frequency per time unit divided by 256. The scale of acceleration parameters (a_max, a_actual, a_threshold) is defined by the parameter ramp_div (see section 8.14, page 26 for details) and depends on the clock frequency of the TMC428. Setting a_max to zero during motion of the stepper motor results in the inability of the stepper motor to stop, because it cannot change its velocity. 8.7.1 a_max_lower_limit & a_max_upper_limit for ramp_div ≠ pulse_div Under special conditions, the parameter a_max might have a lower limit (>1) and might an upper limit ( 2048 and the parameter a_max might be set to any value up to 2047. Important Note: So, a_max can be set without restrictions within its range of 0 to 2047 for those combinations of ramp_div and pulse_div with | ramp_div - pulse_div | ≤ 1. The parameter a_max must not be set below a_max_lower_limit except a_max is set to 0. The condition a_max ≥ a_max_lower_limit as well as a_max ≤ a_max_upper_limit must be satisfied to reach any target position without oscillations. If that condition is not satisfied, oscillations around a target position may occur. For description of the parameters ramp_div and pulse_div see page 26. So, a_max_lower_limit and a_max_upper_limit restrict the allowed range of a_max only for those cases where ramp_div is non-equal to pulse_div and differ more than one. These both limits of a_max concern the deceleration phase for RAMP_MODE and SOFT_MODE only. As long as ramp_div ≥ pulse_div – 1 is valid, any value of a_max within its range (0,1, ..., 2047) is allowed and there exists a valid pair {pmul, pdiv} for each a_max. Qualitative verbalized, this is because the acceleration scaling determined by ramp_div is compatible with the step velocity scaling determined by pulse_div. In other words, large ramp_div stands for low acceleration where large pulse_div stands for low velocity and low acceleration is compatible with low speed and high speed as well, but high acceleration is more compatible with high speed. Important Note: Changing at least one parameter out of the triple {a_max, ramp_div, pulse_div} requires re-calculation of the parameter pair {pmul, pdiv} to update the associated register. For description of the parameters pmul and pdiv see section 8.10, page 19. 8.8 a_actual (IDX=%0111) The actual acceleration, which the TMC428 actually applies to a stepper motor, can be read out by the microcontroller from this read-only register for monitoring purposes. The actual acceleration is used to select scale factors for the coil currents. Internally, it is updated with each clock. The returned value a_actual is smoothed to avoid oscillations of the readout value. Thus, returned a_actual values should not be used directly for precise calculations. 8.9 is_agtat & is_aleat & is_v0 & a_threshold (IDX=%1000) These parameters represent current scaling values Is and are applied to the motor depending on the ramp phase: The parameter is_agtat is applied if the acceleration (a) is greater than (gt) a threshold acceleration (at). This is to increase current during acceleration phases. The parameter is_aleat is applied if the acceleration is lower than or equal to (le) the threshold acceleration. This is the nominal motor current. The third parameter is_v0 is applied if the stepper motor is at rest, to save power, to keep it cool, and to avoid noise probably caused by chopper drivers. The parameter a_threshold is the threshold used to compare with the current acceleration to select the current scale factor. The three parameters is_agtat, is_aleat, and is_v0 are bit vectors of three bit width. One of these is selected conditionally and assigned to an interim bit vector i_scale. The current scaling factor Is is defined in Table 8-1. i_scale 0 0 1 1 0 0 1 1 Is = 100 = 12.5 = 25 = 37.5 = 50 = 62.5 = 75 = 87.5 0 0 0 0 1 1 1 1 0 1 0 1 0 1 0 1 1 1/8 2/8 3/8 4/8 5/8 6/8 7/8 % % % % % % % % Table 8-1: Coil current scale factors Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 19 Important Notes: The maximum current scaling factor 1 is selected by i_scale = %000. This is the power-on default. The minimum current scaling factor 1/8 = 0.125 is selected by i_scale = %001. The current scaling factor Is proportionally reduces the effective number of micro steps per full step. For example, with i_scale = %100 (= 4/8 = 50%) the number of effective micro steps per full step is halved. One of the three scale factors is_agtat, is_aleat, and is_v0 is selected according to Table 8-2. If the velocity is zero, the parameter is_v0 is used for scaling. If the velocity is not zero, either is_aleat or is_agtat is used for scaling, depending on the absolute value of the acceleration and the acceleration threshold a_threshold. v=0 v≠0 | a | ≤ athreshold | a | > athreshold Is := is_v0 Is := is_aleat Is := is_agtat Table 8-2: Current scale selection scheme The automatic motion dependent current scale feature of the TMC428 is provided primarily for micro step operation. It may also be applied for full step or half step drivers, if those provide current control bits. For those drivers, one could initialize the micro step table with a constant function, square function or sine wave using the two most significant DAC bits. The configuration bit continuous_update of the stepper motor global parameter register (Table 9-1, page 30) must be set to ‘1’ to make sure that the coil current is scaled for v=0 if all motors are at rest. 8.10 pmul & pdiv (IDX=%1001) The stepper motors are driven with a trapezoidal velocity profile, which may become triangular if the maximum velocity is not reached (see Figure 8-1, page 16). Depending on the difference between the target position x_target and the actual position x_actual, the ramp generator continuously calculates target velocities v_target for the pulse generator (see Figure 8-2, page 20). The pulse generator then generates (micro) step pulses taking into account the motion parameter limits (v_min, v_max, a_max). With a target velocity proportional to the difference of target position x_target and current position x_actual, the stepper motor approaches the target position. This also works, if the target position is changed during motion. The stepper motor moves to a target position until the difference between the target position x_target and the current position x_actual vanishes. With the right proportionality factor p, target positions are quickly reached and without overshooting them. The proportionality factor primarily depends on the acceleration limit a_max and on the two clock divider parameters pulse_div and ramp_div. These two separate clock divider parameters– set to the same value for most applications –give an extremely wide dynamic range for acceleration and velocity. These two separate parameters allow reaching very high velocities with very low acceleration. If the proportionality factor p is set too small, this results in a slow approach to the target position. If set too large, it causes overshooting and even oscillations around the target position. The calculation of the proportionality factor is simple: The representation of the proportionality factor p by the two parameters p_mul and p_div is some kind of a fixed point representation. It is p = p_mul / p_div with p_mul = {128, 128+1, 128+2, 128+3, ..., 128+127} and Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) p_div = {2 , 2 , 2 , ..., 2 , 2 , 2 }. 3 4 5 14 15 16 th 20 Instead of direct storage of the parameters p_mul and p_div, the TMC428 stores two parameters called pmul and pdiv, with p_mul = 128 + pmul where pmul = {0, 1, 2, 3, ..., 127} and pdiv = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}. The reason why p_mul ranges from 128 to 255 is, that p is divided by p_div which is a power of two ranging from 8 to 65536. So, values of p less than 128 can be achieved by increasing p_div. Note: The parameters pmul and pdiv share a single address (IDX=%1001, see Table 7-2, page 15). The MSB of p_mul is fixed set to ‘1’. So, sending pmul internally sets p_mul = 128 + pmul. In other words, %10000000 = 128 is ORed as bit vector with the content of the register pmul. and p_div = 2 3+pdiv = 2^(3+pdiv) pmul pdiv v_min v_max a_max x_target v_target RAMP GENERATOR x_actual PULSE GENERATOR (micro) step pulses clk32 ramp_div pulse_div clk clock_div32 Figure 8-2: Ramp generator and pulse generator The parameter p has to be calculated for a given acceleration. This calculation is not done by the TMC428 itself, because this task has to be done only once for a given acceleration limit. The acceleration limit is a stepper motor parameter, which is usually fixed in most applications. If the acceleration limit has to be changed nevertheless, the microcontroller could calculate on demand a pair of p_mul and p_div for each acceleration limit a_max and given ramp_div and pulse_div. Also, pre-calculated pairs of p_mul and p_div read from a table maybe sufficient. 8.11 Calculation of p_mul and p_div The proportionality factor p = p_mul / p_div depends on the acceleration limit a_max and frequency pre-divider parameters ramp_div and pulse_div. So, a pair of p_mul / p_div has to be calculated once for each provided acceleration limit a_max. There may exist more than one valid pair of p_mul and p_div for a given a_max. To accelerate, the ramp generator accumulates the acceleration value to the actual velocity with each time step. Internally, the absolute value of the velocity is represented by 11+8 = 19 bits, while only the most significant 11 bits and the sign are used as input for the step pulse 11 generator. So, there are 2 = 2048 values possible to specify a velocity, ranging from 0 to 2047. The 8 ramp generator accumulates a_max divided by 2 = 256 at each time step to the velocity during acceleration phases. So, the acceleration from velocity = 0 to maximum velocity = 2047 spans over 2048* 256 / a_max pulse generator clock pulses. Within that acceleration phase, the pulse generator generates S = ½ * 2048* 256 / a_max * T steps for the (micro) step unit. The parameter T is the clock Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) ramp_div pulse_div ramp_div - pulse_div th 21 divider ratio T = 2 /2 =2 = 2^(ramp_div-pulse_div). During acceleration, the velocity has to be increased until the velocity limit v_max is reached or deceleration is required to reach the target position exactly (see Figure 8-1). The TMC428 automatically decelerates, if required using the difference between current position and target position and the proportionality parameter p, which has to be p = 2048 / S. With this, one gets p = 2048 / ( ( ½ * 2048* 256 / a_max ) * 2^(ramp_div-pulse_div) ). This expression can be simplified to p = a_max / ( 128 * 2^( ramp_div-pulse_div ) ). To avoid overshooting, the parameter p_mul should be made approximately 5% smaller than calculated. Alternatively, one can arrange p reduced by an amount of 5%. If the proportionality parameter p is too small, the target position will be reached slower, because the slow down ramp starts earlier. The target position is approached with minimal velocity v_min, whenever the internally calculated target velocity becomes less than v_min. With a good parameter p the minimal velocity v_min is reached a couple of steps before the target position. With parameter p set a little bit to large and small v_min overshooting of one step respectively one micro step may occur. Decrementation of the parameter pmul avoids such one-step overshooting. Note: Changing at least one parameter out of the triple {a_max, ramp_div, pulse_div} requires recalculation of the parameter pair {pmul, pdiv} to update the associated register if necessary. v(t) v_max p to o sm p all to p od go o ∆v v_min t0 t1 t2 la rg e Figure 8-3: Proportionality parameter p and outline of velocity profile(s) On first approach, to represent the parameter p = p_mul / p_div = (128+pmul) / 2^(3+pdiv) one chooses a pair of pmul and pdiv that approximates p, with pmul in range 0 ... 127 representing p_mul in range 128 ... 255 and pdiv one out of {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13} representing p_div one out of {8, 16 , 32 ,64, 128 , 256, 512, 1024, 2048, 4096, 8192, 16384, 32786, 65536}. There are only 128 * 14 = 1792 pairs of (pmul, pdiv). So, one can simply try all possible pairs (pmul, pdiv) with a program and choose a matching pair. To find a pair, one calculates p = a_max / ( 128 * 2^( ramp_div-pulse_div ) ) and p’ = p_mul / p_div = (128+pmul) / 2^(3+pdiv) and q = p’ / p for each pair (pmul , pdiv) and select one of the pairs satisfying the condition 0.95 < q < 1.0. So, the value q interpreted as a function q(a_max, ramp_div, pulse_div, pmul, pdiv) gives the quality criterion required. Although q = 1.0 indicates that (pmul , pdiv) perfectly represents the desired p for a given a_max, this could cause overshooting because of finite numerical precision. In case of high Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 22 resolution microstepping, overshooting of one micro step is negligible in most applications. To avoid overshooting, use pmul-1 instead of the selected pmul or select a pair (pmul, pdiv) with q = 0.95. The first given source code example ‘pmulpdiv.c’ showing programming in C language based on this brute force approach. Some conversions of the base present equations help to reduce the calculation effort drastically. 8.11.1 Optimized Calculation of p_mul and p_div W ith the equations above, one can simplify the calculation of the parameters pmul and pdiv using the expression pmul = p * 2^3 * 2^pdiv – 128 with p = a_max / ( 128 * 2^( pulse_div – ramp_div ) ). To avoid overshooting, use p_reduced = p * ( 1 – p_reduction[%]) with p_reduction approximately 5% instead of unreduced p. With this, one gets pmul = p_reduced * 2^3 * 2^pdiv – 128 = 0.95 * p * 2^3 * 2^pdiv – 128. W ith this, pmul becomes a function of the parameter pdiv. To find a valid pair {pmul, pdiv} one just has to choose that pair {pmul, pdiv} out of 14 pairs for pdiv = {0, 1, 2, 3, ..., 13} with pmul within the valid range 0 ≤ pmul ≤ 127. An example ‘pmulpdiv.c’ showing programming in C language can be found on page 53. This source code can directly be copied from the PDF datasheet file. 8.12 lp & ref_conf & ramp_mode (rm) (IDX=%1010) The bit called lp (latched position) is a read only status bit. The configuration words ref_conf and ramp_mode are accessed via a common address, because these parameters normally are initialized only once. The configuration bits ref_conf select the behavior of the reference switches, while the two bits ramp_mode (rm) select one of the four possible stepping modes. ramp_mode %00 %01 %10 %11 mode RAMP_MODE SOFT_MODE VELOCITY_MODE HOLD_MODE function default mode for positioning applications with trapezoidal ramp similar to RAMP_MODE, but with soft target position approaching mode for velocity control applications, change of velocities with linear ramps velocity is controlled by the microcontroller, motion parameter limits are ignored Table 8-3 - Outline of TMC428 motion modes The mode called RAMP_MODE is provided as the default mode for positioning tasks, while the VELOCITY_MODE is for applications, where stepper motors have to be driven precisely with constant velocity. The SOFT_MODE is similar to the standard RAMP_MODE except that the target position is approached exponentially reduced velocity. This feature can be useful for applications where vibrations at the target position have to be minimized. The HOLD_MODE is provided for motion control applications, where the ramp generation is completely controlled by the microcontroller. The TMC428 has three reference switch inputs REF1, REF2, REF3. Without additional hardware, three reference switches are available. These switches can be used as reference switches and can be Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 23 used as automatic stop switches as well. Per default, one reference switch input is assigned individually to each stepper motor as a left reference switch (see Figure 9-3, page 32). The reference switch input REF3 can alternatively be assigned as the right reference switch of stepper motor number one (see Figure 9-4, page 32). In that configuration a left and a right reference switch is assigned to stepper motor one, a left reference switch is assigned to stepper motor two, and no reference switch is assigned to stepper motor three. The bit named mot1r in the stepper motor global parameter register (rrs=1 & address=%111111) selects one of these configurations. With additional hardware, up to six reference switches– a left and a right one assigned to each stepper motor –are supported. The additional hardware is just a 74HC157, where three of four 2-to-1-multiplexers are used (see Figure 9-5, page 32). The feature of multiplexing is controlled by the bit named refmux in the stepper motor global parameter register (rrs=1 & address=111111). A reference switch can be used as an automatic stop switch. The reference switch indicates the reference position within a given tolerance. The automatic stop function of the switches can be enabled or disabled. Also a reference tolerance range (see register dx_ref_tolerance, page 27) can be programmed, to allow motion within the reference switch active range during reference point search. When a reference switch is triggered, the actual position can be stored automatically. This allows precise determination of the reference point. This is initiated by writing a dummy value to register x_latched (see page 27). The read-only status bit lp (latch position waiting) then indicates that the next active edge at the selected reference switch will trigger latching the position x_actual. The lp bit is automatically reset after position latching. motor left switch right switch traveller x1 negative direction mechanical inaccuracy of switches (switching hysteresis) xleft x2 xtraveler x3 xright x4 positive direction dx_ref_tolerance Figure 8-4: Left switch and right switch for reference search and automatic stop function ref_conf mnemonic function DISABLE_STOP_L 0 : Stops a motor if velocity is negative (v_actual < 0) and the left reference switch becomes active. 1 : Left reference switch is disabled as a an automatic stop switch. DISABLE_STOP_R 0 : Stops a motor if velocity is positive (v_actual > 0) and the right reference switch becomes active. 1 : Right reference switch is disabled as an automatic stop switch. SOFT_STOP 0 : Stopping takes place immediately, motion parameter limits are ignored. 1 : Stopping takes place in consideration of motion parameter limits, stops with linear ramp. REF_RnL 0 : The left reference switch controls reference switch functions. 1 : The right (not left) reference switch controls reference switch functions. lp 0 : This is the power-on default of the lp (latched position waiting) bit. 1 : A write access initialized x_latched to latch the position if the reference switch becomes active. It is set to ‘0’ after a position is latched. Table 8-4: Reference switch configuration bits (ref_conf) Note: Definition of the reference switch by the configuration bit REF_RnL has no effect on the stop function of the reference switches if DISABLE_STOP_L=’0’ respectively DISABLE_STOP_R=’0’. The Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 24 bit REF_RnL (reference switch Right not Left) defines which switch is the reference switch: If set to ‘1’, the right, else (set to ‘0’) the left one is the reference switch. The bits contained in ref_conf control the semantic and the actions of the reference/stop switch modes for interrupt generation as explained later. The stepper motor stops if the reference/stop switch, which corresponds to the actual driving direction, becomes active. The configuration bits named DISABLE_STOP_L respectively DISABLE_STOP_R disable these automatic stop functions. If the bit SOFT_STOP is set, motor stop forced by a reference switch is done within motion parameter limits while otherwise stopping is abruptly. Hint: There is a functional difference between reference switches and stop switches. Reference switches are used to determine a reference position for a stepper motor. Stop switches are used for automatic stopping a motor when reaching a limit. The signals of switches are processed via the inputs named REF1, REF2, REF3 might be used as automatic stop switches, reference switches, or both. 32 bit DATAGRAM sent from a µC to the TMC428 33222222222211111111119876543210 1098765432109876543210 RRS 0 RW ADDRESS smda DATA lp 1010 ref_conf rm %00 : RAMP, %01 : SOFT, %10 : VELOCITY, %11 : HOLD Table 8-5: lp & ref_conf & ramp_mode (rm) data bit positions 8.13 interrupt_mask & interrupt_flags (IDX=%1011) The TMC428 provides one interrupt register of eight flags for each stepper motor. Interrupt bits are named INT_. An interrupt bit can set back to ‘0’ by writing ‘1’ to it. Each interrupt bit can either be enabled (‘1’) or disabled (‘0’) individually by an associated interrupt mask bit named MASK_. The interrupt flags are forced to ‘0’ if the corresponding mask bit is disabled (‘0’). The bit mapping of the interrupt mask bits and interrupt bits itself is diagrammed in Table 8-7 on page 25. The interrupt out SDO_C / nINT is set active low – where the interrupt status bit INT is set active high - when at least one interrupt flag of one motor becomes set. The interrupt mask enables or disables each interrupt mask individually. So, if the interrupt status is inactive, nINT is high (‘1’) and INT is low ('0'). The interrupt status is mapped to the most significant bit (31) of each datagram sent back to the µC (see Table 6-4, page 12) and it is only available at the SDO_C / nINT pin of the TMC428 if the pin nSCS_C is high. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG latched position (waiting) DISABLE_STOP_L DISABLE_STOP_R SOFT_STOP REF_RnL TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 25 Demultiplexing of the multiplexed interrupt status signal at the pin SDO_C / nINT can be done using additional hardware. It is not necessary if the microcontroller always disables its interrupt while it sends a datagram to the TMC428. interrupt bit mnemonic function INT_POS_END stepper motor reached target position INT_REF_WRONG reference switch signal was active outside (dx_ref_tolerance) INT_REF_MISS reference switch signal missing at null position INT_STOP stop forced by reference switch during motion INT_STOP_LEFT_LOW high to low transition of left reference switch INT_STOP_RIGHT_LOW high to low transition of right reference switch INT_STOP_LEFT_HIGH low to high transition of left reference switch INT_STOP_RIGHT_HIGH low to high transition of right reference switch the reference switch tolerance range Table 8-6: interrupt bit mnemonics 32 bit DATAGRAM sent from a µC to the TMC428 33222222222211111111119876543210 1098765432109876543210 RRS 0 RW ADDRESS smd a 1 0 1 1 DATA interrupt mask MASK_STOP_RIGHT_HIGH MASK_STOP_LEFT_HIGH MASK_STOP_RIGHT_LOW MASK_STOP_LEFT_LOW MASK_STOP MASK_REF_MISS MASK_REF_WRONG MASK_POS_END INT_STOP_RIGHT_HIGH INT_STOP_LEFT_HIGH interrupt flags INT_STOP_RIGHT_LOW INT_STOP_LEFT_LOW INT_STOP INT_REF_MISS INT_REF_WRONG INT_POS_END Table 8-7: interrupt register & interrupt mask An interrupt flag is set to ‘1’ if its assigned interrupt condition occurs and the corresponding interrupt mask is set (‘1’). Interrupt flags are reset to ‘0’ by a write access (RW=’0’) to the interrupt register address (IDX=%1011) with a ‘1’ at the position of the bit to be cleared. Writing a ‘0’ to the corresponding position leaves the interrupt flag untouched. If an end position is reached while the interrupt mask MASK_POS_END is ‘1’, the bit named INT_POS_END is set to one. The switches processed via the inputs REF1, REF2, REF3 can be used as stop switches for automatic motion limiting, as reference switches and for both. If a reference switch becomes active out of the reference switch tolerance range– defined by the dx_ref_tolerance register –the interrupt flag INT_REF_WRONG is set if its interrupt mask bit MASK_REF_WRONG is set. The interrupt flag INT_REF_MISS is set if the reference switch is inactive at the 0 position and the mask MASK_REF_MISS is enabled. The INT_STOP flag is set, if the reference switch has forced a stop and if the interrupt mask MASK_STOP is set. The INT_STOP_LEFT_LOW flag is set if the reference switch changes from high to low and if the interrupt mask bit MASK_STOP_LEFT_LOW is set. The interrupt flag INT_STOP_RIGHT_LOW is similar to INT_STOP_LEFT_LOW but for the right reference switch. The INT_STOP_LEFT_HIGH indicates that the left reference switch input changes from low to Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 26 high if the mask MASK_STOP_LEFT_HIGH is set. The INT_STOP_RIGHT_HIGH indicates it for the right reference switch if the mask MASK_STOP_LEFT_HIGH is set. 8.14 pulse_div & ramp_div & usrs (IDX=%1100) The frequency of the external clock signal (see Figure 4-1, page 6, pin CLK) is divided by 32 (see Figure 8-2, page 20, block clk_div32). This clock drives two programmable clock dividers for the ramp generator and for the pulse generator. The pulse generator clock– defining the maximum step pulse rate –is determined by the parameter pulse_div. The pulse rate R is given by R[Hz] = f_clk[Hz] * velocity / ( 2^pulse_div * 2048 * 32 ) where f_clk[Hz] is the frequency of the external clock signal. The parameter velocity is in range 0 to 2047 and represents parameters v_min, v_max and absolute values of v_target and v_actual. So, the pulse generator of the TMC428 would generate one step pulse with each pulse generator clock pulse if the velocity could be set to 2048. The full step frequency RFS[Hz] = R[Hz] / 2^usrs. The change ∆R in the pulse rate per time unit (pulse frequency change per second – the acceleration) is given by ∆R[Hz/s] = f_clk[Hz] * f_clk[Hz] * a_max / ( 2^(pulse_div+ramp_div+29) ). The constant 29 within the exponent is because 2^29 = 2^5 * 2^5 * 2^8 * 2^11 = 32*32*256*2048, where 32 comes from fixed clock pre-dividers, 256 comes from velocity accumulation clock pre-divider, and 2048 comes from velocity accumulation clock divider programmed by a_max. The parameter a_max is in range 0 to 2047. So, the parameter ramp_div scales the acceleration parameter a_max, where the parameter pulse_div scales the velocity parameters. ∆RFS[Hz] = ∆R[Hz] / 2^usrs. significant DAC bits (controlling current amplitude) 5 (MSB) 5 (MSB), 4 5 (MSB), 4, 3 5 (MSB), 4, 3, 2 5 (MSB), 4, 3, 2, 1 5 (MSB), 4, 3, 2, 1, 0 (LSB) usrs 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 [microsteps / full step] 1 2 4 8 16 32 64 comment full step (constant current amplitude) half step microstepping Table 8-8: micro step resolution selection (usrs) parameter The angular velocity of a stepper motor can be calculated based on the full step frequency Rfs[Hz] for a given number of full steps per rotation. Similar, the angular acceleration of a stepper motor can be calculated based on the change of full step frequency per second ∆RFS[Hz]. The three bit wide parameter usrs (micro (µ) step resolution selection, where u represents µ) determines the micro step resolution for its associated stepper motor according to Table 8-8. There is an individual set of 6 DAC bits provided for each of the two phases (coils) for current control to provide up to 64 micro steps per full step. Depending on the micro step resolution, a subset of 6 DAC bits is significant. Using full stepping, the current amplitude is constant for both phases (coils) of a stepper motor and the polarity of one phase (coil) changes with each full step. The micro step counters are initialized to 0 during poweron reset. With each micro step an associated counter accumulates the programmed micro step resolution value usrs. Generally, the number of steps S during linear acceleration a to a velocity v is given by S = ½ * v^2 / a. With v = R[Hz] and a = ∆R[Hz/s] one gets S = ½ * velocity^2 / a_max * 2^ramp_div / 2^pulse_div / 2^3. The number of full steps SFS is SFS = S / 2^usrs. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 27 8.15 dx_ref_tolerance (IDX=%1101) The switches processed via the inputs REF1, REF2, REF3 can be used as stop switches for automatic motion limiting and as reference switches defining a reference position for the stepper motor. To allow the motor to drive near the reference point, it is possible to exclude a motion range of steps from the stop switch function. The parameter dx_ref_tolerance disables automatic stopping by a switch around the origin (see Figure 8-4, page 23). To use the dx_ref_tolerance fare from the origin, the actual position has to be suitable adapted, e.g. to use it for a left side reference switch. Additionally, the parameter dx_ref_tolerance affects interrupt conditions as described before (section 8.13, page 24). 8.16 x_latched (IDX=%1110) This read-only register stores the actual position read from the register x_actual if the reference switch becomes active. The reference switch is defined by the bit REF_RnL of the configuration register lp & ref_conf & ramp_mode. Writing a dummy value to the (read-only) register x_latched initializes the position storage mechanism. Then the actual position is saved with the next rising edge signal of the reference switch depending on the actual motion direction of the stepper motor. The actual position is latched if the switch defined as the reference switch by the REF_RnL bit (see Table 8-4: Reference switch configuration bits (ref_conf), page 23). The status bit lp signals, if latching of a position is pending. An event at the reference switch associated to the actual motion direction takes effect only during motion (when v_actual ≠ 0). 8.17 Unused Address (IDX=%1111) This register address (idx=%1111) within each stepper motor register block {smda=%00, %01, %10} is unused. Writing to this register has no effect. However, access should be avoided, because this address space may be used for future devices. Reading this register gives back the actual status bits and 24 data bits set to ‘0’. 9 Global Parameter Registers The registers addressed by RRS=0 with SMDA=%11 are global parameter registers. To emphasize this difference, the JDX is used as index name instead of IDX. 9.1 datagram_low_word (JDX=%0000) & datagram_high_word (JDX=%0001) The TMC428 stores datagrams sent back from the stepper motor driver chain with a total length of up to 48 bits. The register datagram_low_word holds the lower 24 bits of this 48 bits and the register datagram_high_word holds the higher 24 bits of the 48 bits. These registers together form a 48 bit shift register, where the data from pin SDI_S are shifted left into it with each datagram bit sent to the stepper motor driver chain via the signal SDO_S. A write to one of these read-only registers initializes them, to update their contents with the next datagram received from the drivers chain. datagram_high_word LD2 LD1 LD0 1 OT OTPW UV OCHS OLB OLA OCB OCA 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 last TMC246 driver of the chain (stepper motor #1) datagram_low_word LD2 LD1 LD0 1 OT OTPW UV OCHS OLB OLA OCB OCA LD2 LD1 LD0 1 OT OTPW UV OCHS OLB OLA OCB OCA 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 SDI_S second TMC246 driver of the chain (stepper motor # 2) first TMC246 driver of the chain (stepper motor # 3) Figure 9-1: Example of status bit mapping for a chain of three TMC246 or TMC249 Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 28 The CDGW (= Cover DataGram Waiting, see section 9.3 on page 28) status bit is set to 1 until a datagram is received from the stepper motor driver chain. For read out of datagram_low_word and datagram_high_word the CDGW status bit is important to be able to detect when a datagram transfer has been completed after an initial write to one of the two registers. The fact that the CDGW is formed by logical OR between the cover datagram status and the status of the datagram_low_word and datagram_high_word causes no restriction concerning its usage. This is because a write to the cover_datagram register forces sending a datagram which results in an update of the datagram_low_word and datagram_high_word registers. One the other side, if the cover_datagram mechanism is not used, the CDGW status bit is exclusively available as the status signal of datagram_low_word and datagram_high_word. 9.2 cover_pos & cover_len (JDX=%0010) The TMC428 provides direct sending of datagrams from the microcontroller to the stepper motor drivers. This may be necessary for initialization of different driver chips and useful for reconfiguration purposes. A datagram with up to 24 bits can be transferred to the stepper motor driver by covering one datagram sent to the driver chain. The parameter cover_pos defines the position of the first datagram bit to be covered by the cover_datagram (JDX=%0011) of length cover_len. In contrast to the datagram numbering order of bits, the position count for the cover datagram starts with 0. The cover_datagram bits indexed from cover_len-1 to 0 cover the datagram sent to the drivers chain. Important Note: A step bit used to control stepper motor drivers must not be covered while a motor is running. This is because the coverage of a step bit would cause losing that associated step if the step bit is active. The TMC428 stores cover_pos+1 instead of cover_pos due to internal requirements. So, one writes cover_pos but reads back cover_pos+1. The cw (= cover waiting) bit available by read out of this register. The CDGW status bit (see section 9.3) is the result of logical OR between cw and an internal signal that indicates the status of the stepper motor serial driver chain send register. 9.3 cover_datagram (JDX=%0011) This register holds up to 24 bit of a cover datagram. A cover datagram covers the next datagram sent to the stepper motor driver chain. If no datagrams are sent to the drivers chain, the cover datagram is sent immediately if a cover datagram is written into this register. The status of the cover datagram is mapped to the status bits sent back with each datagram (see Table 6-4, page 12, CDGW status bit). This status bit is also available for readout of cover_pos & cover_len (JDX=%0010), where CDGW is the most significant data bit (23). 48 datagram bits send to the stepper motor driver chain position=39: cover_pos = 39 datagram bits #39 to #46 covered by cover_datagram bits #6 to #0 0 1 2 3 4 5 6 7 8 9 10 11 12 34 35 36 37 38 39 6 40 5 41 4 42 3 43 2 45 1 46 0 47 cover datagram bits #6 to #0 cover the 7 datagram bits #39 to #46 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 (MSB) 5 4 3 2 1 0 (LSB) MSB of the cover datagram (here bit #6) is sent first. up to 24 cover_datagram bits length = 7: cover_len = 7 Figure 9-2: Cover datagram example Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 29 The CDGW (= Cover DataGram Waiting) status bit has to be checked before writing a new cover datagram into this register, to be sure that no cover datagram is waiting to be processed. The CDGW bit is set to 1 until the cover_datagram is sent. The CDGW status bit is also be used as a status bit for the datagram_low_word and datagram_high_word (see section 9.1 on page 27). An example for the cover datagram is given in Figure 9-2 on page 28. In that example 7 bits cover 7 bits of a 48 bit datagram from bit number 39 to bit number 46. A cover datagram with length=0 forces sending an unchanged datagram to the driver chain. 9.4 Unused Addresses (JDX={%0011, ..., %0111, %1001, ..., %1101}) There are unused addresses within the address range of the global parameter registers. Access to these addresses has no effect. How ever, access should be avoided, because this address space may be used for future devices. 9.5 power_down (JDX=%1000) A write to the register address named power_down sets the TMC428 into the power down mode until it detects a falling edge at the pin nSCS_C. During power down, all internal clocks are stopped, all outputs remain stable, and all register contents are preserved. 9.6 Reference Switches l3 & r3 & l2 & r2 & l2 & r1 (JDX=%1110) The current state of all reference switches– demultiplexed internally by the TMC428 if left and right reference switches are used –can be read from this read-only register. The bit named continuous_update of the Stepper Motor Global Parameter Register (JDX=%1111) is important for reading out of reference switches as explained below. 9.7 Stepper Motor Global Parameter Register (JDX=%1111) This register holds different configuration bits for the stepper motor driver chain. The absolute address (RRS & ADDRESS) of the stepper motor global parameter register is %01111110 = $7E (see Table 7-2, page 15, and Table 9-1, page 30). For the datagram configuration the number of stepper motor drivers is important. It is represented by the parameter LSMD (Last Stepper Motor Driver). The parameter LSMD has to be set to %00 for one stepper motor driver, %01 for two stepper motor drivers, and %10 for three stepper motor drivers (see Table 9-2). Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 30 32 bit DATAGRAM sent from a µC to the TMC428 33222222222211111111119876543210 1098765432109876543210 RRS 0 RW continuous_update refmux mot1r ADDRESS 111111 DATA clk2_div csCommonIndividual polarities LSMD last stepper motor driver polarity_DAC_AB polarity_nscs_s polarity_PH_AB polarity_sck_s polarity_FD Table 9-1: Stepper motor global parameter register LSMD %00 (=0) %01 (=1) %10 (=2) %11 (=3) number of stepper motor drivers 1 2 3 NOT ALLOWED Table 9-2: Global parameter LSMD (last stepper motor driver) Five bits are used to control signal polarities. The polarity of the selection signal nSCS_S for the stepper motor driver chain is controlled by the polarity bit polarity_nscs_s. The nSCS_S signal is low active if this bit is set to ‘0’ and it is high active, if this bit is set to ‘1’. The polarity of the stepper motor driver chain clock signal SCK_S is defined by the bit polarity_sck_s. If this bit is ‘0’, the clock polarity is according to Figure 6-3 on page 10. The clock signal SCK_S is inverted if it is set to ‘1’. The bit polarity_PH_AB defines the polarity of the phase bits for the stepper motor. Inverting this bit changes the rotation direction of the associated stepper motor. The bit polarity_FD defines the polarity of the fast decay controlling bit. If it is ‘0’ fast decay is high active and if it is ‘1’ fast decay is low active. The bit named polarity_DAC_AB defines the polarity of the DAC bit vectors. If it is ‘0’ the DAC bits are high active and if it is ‘1’ the DAC bits are inverted – low active. The bit named csCommonIndividual defines either if a single chip select signal nSCS_S is used in common for all stepper motor driver chips (TMC236, TMC239, TMC246, TMC249) or three chip select signals nSCS_S, nSCS2, nSCS3 are used to select the stepper motor driver chips individually. This feature is useful only for the TMC428 within the larger packages, where the two additional chip select signals nSCS2, nSCS3 are available (see Figure 2-2). The one common chip select signal nSCS_S is used if the bit named csCommonIndividual=‘0’. The polarity control bit for the nSCS_S signal must be set to polarity_nscs_s=’0’ if csCommonIndividual=’1’. The chip select polarity is always negative for three individual chips select signals. The eight bits named clk2_div determine the clock frequency of the stepper motor driver chain clock signal SCK_S. The frequency f_sck_s[Hz] of the stepper motor driver chain clock signal SCK_S is f_sck_s[Hz] = f_clk[Hz] / ( 2 * (clk2_div+1) ). A value of 255 (%11111111, $FF) is the upper limit for the parameter clk2_div. With clk2_div = 255 the clock frequency of SCK_S is at minimum. Due to internal processing, a value of 7 (%00000111, $07) is the lower limit for the clock divider parameter Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 31 clk2_div. With clk2_div = 7 the clock frequency of SCK_S is at maximum. A value of clk2_div = 7 is sufficient for the drivers TMC236 / TMC239 / TMC246 / TMC249. Note: For most applications, a setting of clk2_div = 7 is recommended. For smooth motion even at high step frequencies the frequency f_sck_s[Hz] of the clock signal SCK_S should be as high as possible that is compatible with the used drivers. The frequency f_sck_s[Hz] of SCK_S does not become higher for clk2_div < 7, but the signal SCK_S becomes asymmetric with respect to its duty cycle. An asymmetric duty cycle may cause malfunction of stepper motor drivers, where stepper motor driver chips may work correctly in particular at low clock frequencies of CLK. So, the range of clk2_div is {7, 8, 9, . . ., 253, 254, 255}. The default value after power-on reset is clk2_div = 15. The clock frequency f_sck_s[Hz] of SCK_S should be set as high as possible by choosing the parameter clk2_div in consideration of the data clock frequency limit defined by the slowest stepper motor driver chip of the daisy chain. If step frequencies reach the order of magnitude of the maximum datagram frequency– determined by the clock frequency of SCK_S and by the datagram length –the step frequencies may jitter, which is an inherent property of that serial communication. Up to which level variations of step frequencies are acceptable depends on the application. Using microstepping driver chips– as provided by TMC236 / TMC239 / TMC246 / TMC249 driver chips –avoids this problem. The datagram frequency is f_datagram[Hz] = f_sck_s[Hz] / ( 1 + datagram_length[bit] + 1). This formula is an approximation for the upper limit. For clk2_div = 7 the processing of the NxM bit requires 1 SPI clock cycle, where the processing of the NxM bit requires 1.5 SPI clock cycles for clk2_div > 7. So, for a chain of three drivers with 12 bit datagram length each, the upper limit of the datagram frequency is f_datagram[Hz] = f_sck_s[Hz] / ( 1 + 3*(12+1) + 1) = f_sck_s[Hz] / 41. The TMC428 sends datagrams to the stepper motor driver chain on demand only. No datagrams are send if continuous_update is ‘0’ during rest periods. This reduces the communication traffic. The multiplexed reference switch inputs are processed while datagrams are sent to the stepper motor driver chain only. If reference switches are configured to stop associated stepper motors automatically, the configuration bit continuous_update must be set to ‘1’ to force periodic sending of datagrams to the stepper motor driver chain and to sample the reference switches periodically, if all stepper motors are at rest. With this, a stepper motor restarts if its associated reference switch becomes inactive. Without continuous update, a stepper motor stopped by a reference switch would stay at rest until a datagram is sent to the stepper motor driver chain, if its reference switch is inactive. Then, the relevant stepper motor can be moved into the direction opposite to the reference switch or it can be moved in both directions by disabling the automatic stop function. The continuous update datagram frequency is f_cupd_s[Hz] = f_clk[Hz] * ( 1 / 2^ramp_div_0 + 1 / 2^ramp_div_1 + 1 / 2^ramp_div_2 ) / 32768 where ramp_div_0, ramp_div_1, ramp_div_2 are the ramp_div settings of the three stepper motors. The bit continuous_update is also important for the automatic coil current scaling (see page 18). This bit must be set to ‘1’ to be sure that the coil current is also scaled if all motors are at rest. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) +VCC +VCC +VCC th 32 REF1 nSCS_C REF2 REF3 nSCS_S REF_SW3_LEFT REF_SW2_LEFT REF_SW1_LEFT +VCC SDI_C TMC428 SDO_S SCK_C SDO_C CLK V33 V5 TEST GND SCK_S SDI_S Figure 9-3: Reference switch configuration ‘left-side-only’ for mot1r=0 (and refmux=0) +VCC +VCC REF1 nSCS_C REF2 REF3 nSCS_S REF_SW1_RIGHT +VCC REF1_LEFT REF_SW2_LEFT SDI_C TMC428 SDO_S SCK_C SDO_C CLK V33 V5 TEST GND SCK_S SDI_S no reference switch for stepper motor 3 Figure 9-4: Reference switch configuration ‘two-one-null’ for mot1r=1 (and refmux=0) 74HC157 /EN SEL1/ /0 A B C D REF1 nSCS_C REF2 REF3 nSCS_S < MUX A0 A1 B0 B1 C0 C1 D0 D1 REF2_RIGHT REF2_LEFT REF3_RIGHT REF3_LEFT REF1_RIGHT SDI_C TMC428 SDO_S SCK_C SDO_C CLK V33 V5 TEST GND SCK_S SDI_S Figure 9-5: Reference switch multiplexing with 74HC157 (refmux=1) Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG REF_SW1_LEFT TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 33 refmux 0 0 1 1 mot1r 0 1 0 1 motor 1 left switch right switch REF1 % REF1 REF3 REF1_LEFT REF1_RIGHT RE1_LEFT REF1_RIGHT motor 2 left switch right switch REF2 % REF2 % REF2_LEFT REF2_RIGHT REF2_LEFT REF2_RIGHT motor 3 left switch right switch REF3 % % % REF3_LEFT REF3_RIGHT REF3_LEFT REF3_RIGHT Table 9-3: Association of reference inputs depending on configuration bits refmux & mot1r If continuous_update is ‘1’, internal reference switch bits are updated periodically, even if all stepper motors are at rest. Additionally, the chip select signal nSCS_S for the stepper motor driver chain is also the control signal for a multiplexer in case of using the reference switch multiplexing option (see Figure 9-5). So, the continuous_update must be set to ‘1’ if automatic stop by reference switches is enabled, if six multiplexed reference switches are used, and to get the states of reference switches while all stepper motors are at rest. The bit named refmux must be set to ‘1’ to enable reference switch multiplexing (see Figure 9-5). For the two variants TMC428-PI24 and TMC428-DI20, the reference switch multiplexing also works for csCommonIndividual=’1’ using three separate driver selection signals (nSCS_S, nSCS2, nSCS3) if the signal nSCS_S is connected to the multiplexer 74HC157 according to Figure 9-8. If reference switch multiplexing is enabled, mot1r is ignored. With refmux set to ‘0’, the association of the reference switch inputs REF1, REF2, REF3 depends on the setting of the configuration bit mot1r. The power-on default value of mot1r is ‘0’. With that default value, REF1 is associated to the left reference switch of stepper motor #1, REF2 is associated to the left reference switch of stepper motor #2, and REF3 is associated to the left reference switch of stepper motor #3. If mot1r is set to ‘1’ the input REF1 is also associated with the left reference switch of stepper motor #1. REF2 is also associated to the left reference switch of stepper motor #2. But, the input REF3 is associated to the right reference switch of stepper motor #1 and no reference switch input is associated to stepper motor number#3 (see Figure 9-4). After power-on-reset, per default refmux=0 and mot1r=0 selects the single reference switch configuration outlined in Figure 9-3, where each reference switch input (REF1, REF2, REF3) is assigned individually to one each stepper motor as the left reference switch. 9.8 Triple Switch Configuration The programmable tolerance range around the reference switch position is useful for a triple switch configuration, as outlined in Figure 9-6. In that configuration two switches are used as automatic stop switches, and one additional switch is used as the reference switch between the left stop switch and the right stop switch. The left stop switch and the reference switch are wired or. After successful reference search, programming a tolerance range into the register dx_ref_tolerance allows to disable automatic stop within the range of the reference switch only. left stop switch motor reference switch right stop switch traveller x'1 x'left x'2 negative direction xtraveler x1 x0 x2 x3 xright x4 positive direction dx_ref_tolerance Figure 9-6: Triple switch configuration 'left stop switch - reference switch - right stop switch' Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 34 reference switch motor traveller dx1 negative direction mechanical inaccuracy of switches (switching hysteresis) x1 xref x2 dx2 xtraveler xmax positive direction dx_ref_tolerance Figure 9-7: Reference search 9.9 Reference Search The goal of the reference search is to determine the position xref of a reference switch (see Figure 9-7). Due to mechanical inaccuracy of switches, the reference switch is active within a range x1 < xref < x2, where x1 and x2 may vary. If the traveler is within the range x1 < xtraveler < x2 before reference search, it is necessary to go outside this range, because the associated reference switch is active. A dummy write access to x_latched initializes the position latch register. Then, with the traveler within the range x2 < xtraveler < xmax and the initialized register x_latched, the position x2 can simply be determined by motion with a target position x_target set to -xmax. When reaching the position x2, this position is latched automatically. With stop switch enabled, the stepper motor automatically stops if the position x2 is reached. Then, the dx_ref_tolerance has to be set, so that motion within the active reference switch range x1 < xref < x2 is allowed and to move the traveler to a position xtraveler < x1 if desired. Then the register x_latched has to be initialized again to latch the position x1 by a motion to a target position xtraveler < x1. When the positions x1 and x2 are determined the reference position xref = (x1 + x2 ) / 2 can be set. Finally, one should move to the target position x_target = xref and set x_target := 0 and x_actual := 0 when reached. 9.10 Simultanous Start of up to Three Stepper Motors Starting stepper motors simultaneously can be acheved by sending successive datagrams starting the stepper motors. If the delay between those datagrams is of the magnitude of some microseconds, the stepper motors can be considered as started simultaneously. Feeding the reference switch signals through or gates (see Figure 9-8) allows exact simultaneous start of the stepper motors under software control. 74HC157 hold /EN SEL1/ /0 A B C 74HC32 D REF1 nSCS_C REF2 REF3 nSCS_S < MUX A0 A1 B0 B1 C0 C1 D0 D1 REF2_RIGHT REF2_LEFT REF3_RIGHT REF3_LEFT REF1_LEFT REF1_RIGHT +VCC SDI_C TMC428 SDO_S SCK_C SDO_C CLK V33 V5 TEST GND SCK_S SDI_S Figure 9-8: Reference switch gateing for exact simultanous stepper motor start Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 35 10 RAM Address Partitioning and Data Organization The on-chip RAM capacity is 128 x 6 bit. These 128 on-chip RAM cells of 6 bit width are addressed via 64 addresses of 2 x 6 bit (see Table 10-1). So, from the point of view of addressing the on-chip RAM via datagrams, the address space enfolds 64 addresses of 24 bit wide data, where only 2 x 6 = 12 bits are relevant. These 64 addresses are partitioned– selected by the RRS (Register RAM Select, datagram bit 31)– into two address ranges of 32 addresses. The registers of the TMC428 are addressed with RRS=’0’. The on-chip RAM is addressed with RRS=’1’. The 64 on-chip RAM addresses are partitioned into two separate ranges by the most significant address bit of the datagram (bit 30). The first 32 addresses are provided for the configuration of the serial stepper motor driver chain. Each of these 32 addresses stores two configuration words, composed of the so called NxM (Next Motor) bit together with the 5 bit wide primary signal code. While sending a datagram, the primary signal code words are read internally beginning with the first address of the driver chain datagram configuration memory range. Each primary signal code word selects a signal provided by the micro step unit. If the NxM bit is ‘1’ an internal stepper motor addressing counter is incremented. If this internal counter is equivalent to the LSMD (last stepper motor driver) parameter, the datagram transmission is finished and the counter is preset to %00 for the next datagram transmission to the stepper motor driver chain. The second 32 addresses are provided to store the micro step table, which usually is a quarter sine wave period as a basic approach or the quarter period of a periodic function optimized for microstepping of a given stepper motor type. Different stepper motors may step with different micro step resolutions, but the micro step look up table (LUT) is the same for all stepper motors controlled by one TMC428. Any quarter wave period stored in the micro step table is expanded automatically to a full period wave together with its 90° phase shifted wave. 32 bit DATAGRAM sent from a µC to the TMC428 via pin SDI_C 33222222222211111111119876543210 1098765432109876543210 DATA RW ADDRESS data @ odd RAM addresses data @ even RAM addresses RRS 10 11 32 x (2x6 bit) driver chain datagram configuration range 32 x (2x6 bit) quarter period sine wave LUT range quarter sine wave values (amplitude) quarter sine wave values (amplitude) NxM_1 NxM_0 signal_codes signal_codes Table 10-1: Partitioning of the on-chip RAM address space Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 36 11 Stepper Motor Driver Datagram Configuration A number of control signals is required to drive 2-phase stepper motors. The serial driver interface forms the link between the TMC428 an the stepper motor driver chain. The stepper motor driver datagram configuration simply defines the order of the control signals serially sent from TMC428 to the stepper motor driver chain. To define the serial order of the control signals, so called primary signal codes have to be written into the stepper motor driver datagram configuration area of the on-chip configuration RAM of the TMC428. Which control signals are required in a given application, depends on the choice of stepping mode– full step, half step, micro step –and on additional options depending on the stepper motor driver chips used. So, the TMC428 primarily provides a full set of control signals individually for each of the up to three stepper 2-phase stepper motors respectively stepper motor driver chips of the daisy chain. Mnemonics for primary signal codes are given in Table 11-1. Names of these signals may differ to the signal names of the used stepper motor drivers. Figure 11-1 on page 36 outlines the principle of connecting the control signals– internally provided by the TMC428 as parallel signals –with the signals used to control the digital part of a stepper motor driver. DAC_A_0 DAC_A_1 PH_A FD_A DAC_B_0 DAC_B_1 PH_B FD_B Direction Step Zero One ... ... MSB 3x Serial Driver Interface Serial-to-Parallel Interface(s) LSB MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB control signals status signals FD_A DAC_A_5 DAC_A_4 DAC_A_3 DAC_A_2 PH_A FD_B DAC_B_5 DAC_B_4 DAC_B_3 DAC_B2 PH_B MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB Micro Stepping Unit (incl. sequencer) status signals n Stepper Motor Driver Control Logic TMC428 Multiple Ported RAM Stepper Motor Driver (Chain) e.g. TMC236 / TMC239 / TMC246 / TMC249 status signals n Figure 11-1: Serially transmitted control and status signals between TMC428 and driver chain PRIMARY SIGNAL CODE hex bin $00 %00000 $01 %00001 $02 %00010 $03 %00011 $04 %00100 $05 %00101 $06 %00110 $07 %00111 $08 %01000 $09 %01001 $0A %01010 $0B %01011 $0C %01100 $0D %01101 $0E %01110 $0F %01111 $10 %10000 MNEMONIC DAC_A_0 DAC_A_1 DAC_A_2 DAC_A_3 DAC_A_4 DAC_A_5 PH_A FD_A DAC_B_0 DAC_B_1 DAC_B_2 DAC_B_3 DAC_B_4 DAC_B_5 PH_B FD_B Zero FUNCTION DAC A, bit 0 (LSB) DAC A, bit 1 DAC A, bit 2 DAC A, bit 3 DAC A, bit 4 DAC A, bit 5 (MSB) phase polarity bit A fast decay bit A DAC B, bit 0 (LSB) DAC B, bit 1 DAC B, bit 2 DAC B, bit 3 DAC B, bit 4 DAC B, bit 5 (MSB) phase polarity bit B fast decay bit B constant ‘0’ COIL A COIL B Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) One Direction Step $11 $12 $13 $14 $15 $16 $17 $18 $19 $1A $1B $1C $1D $1E $1F %10001 %10010 %10011 %10100 %10101 %10110 %10111 %11000 %11001 %11010 %11011 %11100 %11101 %11110 %11111 constant ‘1’ 0 : up / 1 : down resp. counter clockwise / clockwise step bit for step/direction control of drivers th 37 UNUSED (these codes might be used for future devices) ‘1’ for TMC428-I, TMC428-A, TMC428-PI24, TMC428-DI20 Table 11-1: Primary signal codes The control signals for each of the two coils of a 2-phase stepper motor are 6 bits for the DAC controlling the current of a coil, a phase polarity bit, and a fast decay bit for those stepper motor driver chips with a fast decay feature for the coil current. These signals are available individually for each coil (COIL A and COIL B). Constant configuration bits named Zero and One are provided. Additionally, step and direction bits are available. One unique 5 bit code word– named primary signal code –is assigned to each primary control signal (see Table 11-1). The micro step unit (including sequencer) provides the full set of control signals for three stepper motor driver chips. A subset of these control signals is selected by the stepper motor driver datagram configuration, which is stored within the first 32 addresses representing 64 values of the on-chip RAM (see Table 10-1, page 35). The stepper motor drivers are organized in a daisy chain. So the addressing of the stepper motor driver chips within the daisy chain is by its position. As mentioned before, the TMC428 sends datagrams to the stepper motor driver chain on demand. To guarantee the integrity of each datagram sent to the stepper motor driver chain, the status of all primary control signals is buffered internally before sending. Afterwards, the transmission starts with selection of the buffered primary control signals of the first motor (smda=%00) by reading the first primary signal code word (even data word at on-chip RAM address %00000) from on-chip configuration RAM area. The primary signal codes select the primary signals provided for the first stepper motor. The first stepper motor is addressed until the NxM (next motor) bit is read from on-chip configuration RAM. The stepper motor driver address is incremented with each NxM=’1’ as long as the current stepper motor driver address is below the value set by the parameter LSMD (last stepper motor driver). If the stepper motor driver address is equivalent to the LSMD parameter, a NxM=’1’ indicates the completion of the transmission. With that, the stepper motor driver address counter of the serial interface is reinitialized to %00 and the unit waits for the next transmission request. So, the order of primary signal codes in the on-chip RAM configuration area determines the order of datagram bits for the stepper motor driver chain, whereas the prefixed NxM bit determines the stepper motor driver positions. If no NxM bit with a value of ‘1’ is stored within the on-chip RAM, the TMC428 will send endlessly. So, the on-chip RAM has to be configured first. After power-on reset, the registers of the TMC428 are initialized in a way, that no transmission of datagrams to the motor driver chain is required. Access to on-chip RAM is always possible, also during transmission of datagrams to the driver chain. 11.1 Initialization of on-chip-RAM by µC after power-on All registers are initialized by the automatic power-on reset. The registers are initialized, and the stepper motors are at rest. The on-chip RAM is not initialized by the power-on reset. Writing to registers may involve action of the stepper motor units initiated by the TMC428 resulting in sending Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 38 datagrams to the stepper motor driver chain. Those datagrams have a random power-on configuration of the on-chip-RAM. So, before trying to move a motor, the on-chip RAM must be initialized first. 11.2 An Example of a Stepper Motor Driver Datagram Configuration The following example demonstrates, how to configure the datagram and shows what has to be stored within the on-chip RAM to represent the desired configuration. That example refers to a driver chain of three TRINAMIC stepper motor drivers of type TMC236, TMC239, TMC246, TMC249. From the TMC428 datagram configuration point of view, there is no difference between these drivers. All these drivers have a serial interface of 12 bits length. The configuration is as follows. For the first and the second stepper motor driver of the chain the fast decay control bit (FD_A, FD_B) is fixed to ‘0’. For the third driver the fast decay control bit are used. The corresponding content of the configuration on-chip RAM is outlined in Table 11-2. The sequence to be sent to the TMC428 for this configuration is outlined in Table 11-3. Hint: The stepper motor driver datagram configuration can be accessed at any time without conflict, e.g. to changed between a configuration using fast decay versus a configuration where fast decay is disabled. RAM RAM TMC428 driver NxM TMC428 position address data mnemonic of bit signal within primary signal code datagram 0 0 $10 $00 $10 Zero 1 0 $05 $01 $05 DAC_A_5 2 0 $04 $02 $04 DAC_A_4 3 0 $03 $03 $03 DAC_A_3 4 0 $02 $04 $02 DAC_A_2 5 0 $06 $05 $06 PH_A 6 0 $10 $06 $10 Zero 7 0 $0D $07 $0D DAC_B_5 8 0 $0C $08 $0C DAC_B_4 9 0 $0B $09 $0B DAC_B_3 10 0 $0A $0A $0A DAC_B_2 11 $0E $0B PH_B 1 $2E 12 0 $10 $0C $10 Zero 13 0 $05 $0D $05 DAC_A_5 14 0 $04 $0E $04 DAC_A_4 15 0 $03 $0F $03 DAC_A_3 16 0 $02 $10 $02 DAC_A_2 17 0 $06 $11 $06 PH_A 18 0 $10 $12 $10 Zero 19 0 $0D $13 $0D DAC_B_5 20 0 $0C $14 $0C DAC_B_4 21 0 $0B $15 $0B DAC_B_3 22 0 $0A $16 $0A DAC_B_2 23 1 $0E $17 $2E PH_B 24 0 $07 $18 $07 FD_A 25 0 $05 $19 $05 DAC_A_5 26 0 $04 $1A $04 DAC_A_4 27 0 $03 $1B $03 DAC_A_3 28 0 $02 $1C $02 DAC_A_2 29 0 $06 $1D $06 PH_A 30 0 $0F $1E $0F FD_B 31 0 $0D $1F $0D DAC_B_5 32 0 $0C $20 $0C DAC_B_4 33 0 $0B $21 $0B DAC_B_3 34 0 $0A $22 $0A DAC_B_2 $0E PH_B 35 1 $23 $2E W ith LSMD = %10 the (third) NxM bit at address $23 (position 35) finishes the datagram transmission driver#1 (SMDA=%00) driver#2 (SMDA=%01) driver#3 (SMDA=%10) TMC23x / TMC24x Bit Name MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB MDA CA3 CA2 CA1 CA0 PHA MDB CB3 CB2 CB1 CB0 PHB → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → → Table 11-2: Datagram example and RAM contents for three stepper motor driver chain Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 39 binary datagram specification %10000000----------000101--010000 %10000010----------000011--000100 %10000100----------000110--000010 %10000110----------001101--010000 %10001000----------001011--001100 %10001010----------101110--001010 %10001100----------000101--010000 %10001110----------000011--000100 %10010000----------000110--000010 %10010010----------001101--010000 %10010100----------001011--001100 %10010110----------101110--001010 %10011000----------000101--000111 %10011010----------000011--000100 %10011100----------000110--000010 %10011110----------001101--001111 %10100000----------001011--001100 %10100010----------101110--001010 : : : : : : : : : : : : : : : : : : : hexadecimal datagram $80000510 $82000304 $84000602 $86000D10 $88000B0C $8a002E0A $8c000510 $8e000304 $90000602 $92000D10 $94000B0C $96002E0A $98000507 $9a000304 $9c000602 $9e000D0F $a0000B0C $a2002E0A Table 11-3: Configuration datagram sequence for the example (with '-' (don't cares)) 12 Initialization of the Micro Step Look-Up-Table The TMC428 provides a look-up-table (LUT) of 64 values of 6 bit for micro stepping. The micro step LUT can be adapted by storing an arbitrary quarter period of a periodic function to match individual stepper motor characteristics. It is common to use one period of a sine wave function for micro stepping. With that function, the current of one phase is driven with the sine function whereas the other phase is driven with the cosine function. To initialize the LUT for micro stepping one simply has to load a quarter sine wave period into the micro step LUT. Two successive values of the sine wave function are included in one datagram similar to the primary signal code words for the stepper motor driver chain configuration. The TMC428 automatically expands the quarter sine wave period to a full sine and cosine function. The necessary data values y(i) to represent a ¼ sine wave period for the micro step LUT are defined by y(i) = int[ ½ + 64 * sin(¼ * 2 * π * i / 64) ] with i = { 0, 1, 2, 3, ..., 60, 61, 62, 63 }, where the conditional replacement y(i) := 63 for y(i) > 63 has to be done. The last five values (which are calculated to be 64) have to be replaced by 63. With this replacement one finally gets y(i) = { 0, 2, 3, 5, 6, 8, 9, 11, 12, 14, 16, 17, 19, 20, 22, 23, 24, 26, 27, 29, 30, 32, 33, 34, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 59, 60, 60, 61, 61, 62, 62, 62, 63, 63, 63, 63, 63, 63, 63, 63 }. 32 bit DATAGRAM sent from a µC to the TMC428 via pin SDI_C 3 1 RRS 1 3222222222211111111119876543210 098765432109876543210 DATA (x)10 2 5 8 11 14 data @ odd RAM addresses 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 1 0 0 1 1 0 0 1 1 0 1 0 1 0 RW ADDRESS 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 0 (x)10 0 3 6 9 12 data @ even RAM addresses 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1 0 1 0 1 1 0 0 0 1 0 1 0 0 Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 40 Table 12-1: Scheme of ¼ sine wave period with 6 bit resolution and 64 ( 32 x 2 ) values These 64 values represent a quarter sine period in the interval [0 ... π/4[ which is expanded automatically by the TMC428 to a full sine cosine period (see section 12.1, page 41). The table is sent to the on-chip RAM of the TMC428 by 32 datagrams: % binary representation of the datagram % 11 00000 0 00000000 00 000010 00 000000 % 11 00001 0 00000000 00 000101 00 000011 % 11 00010 0 00000000 00 001000 00 000110 % 11 00011 0 00000000 00 001011 00 001001 % 11 00100 0 00000000 00 001110 00 001100 % 11 00101 0 00000000 00 010001 00 010000 % 11 00110 0 00000000 00 010100 00 010011 % 11 00111 0 00000000 00 010111 00 010110 % 11 01000 0 00000000 00 011010 00 011000 % 11 01001 0 00000000 00 011101 00 011011 % 11 01010 0 00000000 00 100000 00 011110 % 11 01011 0 00000000 00 100010 00 100001 % 11 01100 0 00000000 00 100101 00 100100 % 11 01101 0 00000000 00 100111 00 100110 % 11 01110 0 00000000 00 101010 00 101001 % 11 01111 0 00000000 00 101100 00 101011 % 11 10000 0 00000000 00 101110 00 101101 % 11 10001 0 00000000 00 110000 00 101111 % 11 10010 0 00000000 00 110010 00 110001 % 11 10011 0 00000000 00 110100 00 110011 % 11 10100 0 00000000 00 110110 00 110101 % 11 10101 0 00000000 00 111000 00 110111 % 11 10110 0 00000000 00 111001 00 111000 % 11 10111 0 00000000 00 111011 00 111010 % 11 11000 0 00000000 00 111100 00 111011 % 11 11001 0 00000000 00 111101 00 111100 % 11 11010 0 00000000 00 111110 00 111101 % 11 11011 0 00000000 00 111110 00 111110 % 11 11100 0 00000000 00 111111 00 111111 % 11 11101 0 00000000 00 111111 00 111111 % 11 11110 0 00000000 00 111111 00 111111 % 11 11111 0 00000000 00 111111 00 111111 : decimal represented pair of values : $ hexadecimal (separated by & character) representation : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2&0 5&3 8&6 11 & 9 14 & 12 17 & 16 20 & 19 23 & 22 26 & 24 29 & 27 32 & 30 34 & 33 37 & 36 39 & 38 42 & 41 44 & 43 46 & 45 48 & 47 50 & 49 52 & 51 54 & 53 56 & 55 57 & 56 59 & 58 60 & 59 61 & 60 62 & 61 62 & 62 63 & 63 63 & 63 63 & 63 63 & 63 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : $C0000200 $C2000503 $C4000806 $C6000B09 $C8000E0C $CA001110 $CC001413 $CE001716 $D0001A18 $D2001D1B $D400201E $D6002221 $D8002524 $DA002726 $DC002A29 $DE002C2B $E0002E2D $E200302F $E4003231 $E6003433 $E8003635 $EA003837 $EC003938 $EE003B3A $F0003C3B $F2003D3C $F4003E3D $F6003E3E $F8003F3F $FA003F3F $FC003F3F $FE003F3F Table 12-2 - Datagrams for initialization of a quarter sine wave period microstep look-up-table Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG … 1 1 1 1 1 … 1 1 1 1 1 … 0 1 1 1 1 … 1 0 0 1 1 … 1 0 1 0 1 … … … … … … … … … … … … 62 63 63 63 63 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 62 63 63 63 63 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 41 These 32 datagrams (Table 12-2) are sufficient for all programmable micro step resolutions. If micro stepping is used for at least one stepper motor, these 32 datagrams have to be sent once to the TMC428 for initialization of the micro step table after power-on reset. The initialization of the micro step look-up-table is not necessary, if full stepping is used for all stepper motors. The on-chip RAM is not initialized during power-on reset. So, the full initialization of the whole micro step look-up-table is recommended to avoid trouble caused by missing look-up table entries. Additionally, a fully initialized micro step look-up-table allows the selection of individual micro step resolutions for different steppes. 12.1 Stepping through the Wave Look-Up-Table The 64 values of the wave look-up table (LUT) hold a quarter period of a sine wave, indexed from 0 to 63. This quarter sine wave is expanded to full sine wave and full cosine wave by indexing the 64 values of the LUT. The LUT index is mapped from a wave index of a full period from 0 to 255. The stepping through the LUT is done with fixed increment width. The increment width is a power of two and it depends on the micro step resolution selection usrs. The Table 12-4 gives the indices for the LUT for the different micro step resolutions. For motion in positive direction, the full period index is incremented from micro step to micro step. For motion into negative direction, the full period index is decremented from micro step to micro step. The sine is associated to phase A (PH_A) and the cosine is associated to phase B (PH_B). The phase bits represent the sign of the sine resp. cosine function. The polarity of the phase bit (PH_A, PH_B) and the polarity of the fast decay control bits (FD_A, FD_B) can be changed by the polarity bits within the global stepper motor parameter register (see section 9.7, page 29). MSBs of full wave index (range) %00 (0...63) %01 (64...127) %10 (128...191) %11 (192...255) Quadrant 1 nd 2 rd 3 th 4 st PH_A (sin) 1 1 0 0 PH_B (cos) 1 0 0 1 FD_A (sin) 0 1 0 1 FD_B (cos) 1 0 1 0 Table 12-3: Phase Bits and Fast Decay Control Bits Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 42 Hints: One should always initialize the whole LUT to be sure to read valid wave values, even if one changes the micro step resolution after some micro steps have been done on higher resolution. Even if one uses e.g. 16 times microstepping, one gets a smoother move for the stepper motor if one initializes the full sine wave LUT according to Table 12-2 - Datagrams for initialization of a quarter sine wave period microstep look-up-table on page 40 and using the MSB DAC bits (DAC_A_5, DAC_A_4, DAC_A_3, DAC_A_2 and DAC_B_5, DAC_B_4, DAC_B_3, DAC_B_2). So, one should always completely initialize the quarter sine wave LUT, no matter what micro step resolution is used. The addressing starts at 0 after power-on reset only. Changing the micro step resolution after some micro steps have been made causes an offset for the addressing that has to be taken into account for positioning a stepper motor. increment width 1 2 4 8 16 32 64 sin cos sin cos sin cos sin cos sin cos sin cos sin cos usrs %110 %101 %100 %011 %010 %001 (HS) %000 (FS) 1st quadrant 0,1,2, 3, ..., 61, 62,63, 63, 63, 62, 61,...,2,1, 0,2, 4, 6, ..., 58, 60,62, 63, 60, 58, 56,..., 4, 2, 0, 4, 8, 12, ..., 56, 60, 63, 60, 56, ..., 12, 8, 4, 0, 8, 16, 24, ... , 48, 56 63, 56, 48, 40,...,16, 8, 0, 16, 32, 48, 63, 48, 32, 16, 0, 32, 63, 32, 0, 63, 2nd quadrant 63, 63, 62, 61,..., 3, 2,1, 0,1,2, 3, ..., 61, 62,63, 63, 60, 58, 56,..., 4, 2, 0,2, 4, 6, ..., 58, 60,62, 63, 60, 56, ..., 12, 8, 4, 0, 4, 8, 12, ..., 56, 60, 63, 56, 48, 40,...,16, 8, 0, 8, 16, 24, ... , 48, 56 63, 48, 32, 16, 0, 16, 32, 48, 63, 32, 0, 32, 63, 0, 3rd quadrant 0,1,2, 3, ..., 61, 62,63, 63, 63,62,61,...,3, 2,1, 0,2, 4, 6, ..., 58, 60,62, 63, 60, 58, 56,..., 4, 2, 0, 4, 8, 12, ..., 56, 60, 63, 60, 56, ..., 12, 8, 4, 0, 8, 16, 24, ... , 48, 56 63, 56, 48, 40,...,16, 8, 0, 16, 32, 48, 63, 48, 32, 16, 0, 32, 63, 32 0, 63 4th quadrant 63, 63,62,61,..., 3, 2,1 0,1,2, 3, ..., 61, 62,63 63, 60, 58, 56,..., 4, 2 0,2, 4, 6, ..., 58, 60,62 63, 60, 56, ..., 12, 8, 4 0, 4, 8, 12, ..., 56, 60 63, 56, 48, 40,...,16, 8 0, 8, 16, 24, ... , 48, 56 63, 48, 32, 16 0, 16, 32, 48 63, 32 0, 32 63 0 Table 12-4: Wave look-up table (LUT) indices for different microstep resolutions 12.2 Partial look-up table initialization option A partially initialized micro step table may be sufficient, if all stepper motors– except those driven in full step mode –are programmed to use the same micro step resolution constantly before a single micro step is processed. But with a partial initialized micro step look-up table, the micro step resolution must not be changed after any step is made after power-on reset. So, a partially initialized look-up table should be taken into account only, if it is a must because of too small memory of the host microcontroller. Instead of partial initialization of the look-up table of the TMC428, initialization with a triangular function frhomb(ϕ) would be a better choice. Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 43 12.3 Micro Step Enhancement Even for stepper motors optimized for sine-cosine control, it is possible to improve micro step behavior by adapting the micro step look-up table (LUT). For different types of stepper motors, a periodic trapezoidal or triangular function similar to a sine function or a superposition of these function as a replacement of the pure sine wave function (Figure 12-1) might be a better choice. Taking the physics of stepper motors into account, the choice of the function for microstepping can be determined by a single shape parameter σ as explained below. The programmability of the micro step look-up table provides a simple and effective facility to enhance microstepping for a given type of two-phase stepper motor. Enhanced microstepping requires accurate current control. So, stepper motor driver chips with enabled and well tuned fast decay (resp. mixed decay) operational mode are need to be used, e.g. TRINAMICs smart power TMC236 / TMC239 / TMC246 / TMC249 drivers. Non-linearity resulting from magnetic field configuration determined by shapes of pole shoes, ferromagnetic characteristics, and other stepper motor characteristics effect non-linearity in micro step behavior of real stepper motors. The non-linearity of microstepping causes micro step positioning displacements, vibrations and noise, which can be reduced dramatically with an adapted micro step table. The best fitting micro step table can be determined by measuring the micro step motor behavior, e.g. using a laser pointer based on the sine-cosine microstepping table. Nevertheless sine-cosine microstepping is a good first order approach for microstepping. The micro step enhancement possible with the TMC428 is based on replacement of the look-up table initialization function sin(ϕ ) used for sine-cosine microstepping by a function with the shape parameter σ. A quarter sine wave period is the basic approach for initialization of the micro step look-up-table . A quarter of a trapezoidal function or a quarter of a triangular function is chosen depending on the shape parameter σ for a given stepper motor type. f f (ϕ )  box _ circle  (ϕ ) =  f (ϕ ) σ circle   f circle _ r hom b (ϕ )  for σ > 0 for σ = 0 for σ < 0 with − 1 .0 ≤ σ ≤ + 1 .0 and 0≤ϕ < π 2 . The look-up table (f(ϕ ) ) of the TMC428 enfolds a quarter period (0 ≤ ϕ < π /2) only. This quarter period is expanded to a full period (0 ≤ ϕ < 2π ) and the phase shifted companion function value (f(ϕ - π /2 )) is added automatically by the TMC428 during operation. So, to reach function value (f(ϕ)), one automatically gets a pair of function values {f(ϕ ); f(ϕ - π /2 )} respectively {sin(ϕ ); cos(ϕ )}. This automatic expansion of the TMC428– primary provided for sine cosine microstepping (f(ϕ ) = sin(ϕ )) – also works fine with other micro step wave forms f σ. f (ϕ ) π 2 y up to 64 m ro ic s ep st in ith w 1 ll fu ep st 0 0 π 4 2π 1 π 2 3π 4 ϕ box rh om b 1 1 2 a nt ra ad qu rc ci le x π up to 64 micro steps 1 full step Figure 12-1: Microstep enhancemant by introduction of a shape function fσ(ϕ ) Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 44 The shape parameter σ selects one of three functions fbox(φ), fcircle(φ), frhomb(φ), respectively a superposition of two of them. The shape parameter σ = 0 selects the function fcircle(φ) which is the sine function sin(ϕ ) as used for sine cosine microstepping. With this, one gets the unit circle (r=1.0) by transformation to Cartesian coordinates {y = sin(ϕ ); x = cos(ϕ )} as outlined in Figure 12-1, a shape parameter σ = +1.0 results in a box, and a shape parameter σ = -1.0 results in a rhomb. Other values except those, result in something between box and circle respectively something between circle an rhomb. The data values y(i) of the look-up table range from 0 to 63 and the argument i ranges also from 0 to 63. In the following, natural angles (radians) ranging from (0 ≤ ϕ < 2π ) are used for the description. The three functions for superposition controlled by the shape parameter σ are 4 ⋅ϕ   f box (ϕ ) = π ⋅ 2 1   2  f circle (ϕ ) = sin(ϕ ) 2 f r hom b (ϕ ) = ⋅ϕ if if 0 ≤ϕ < π 4 ϕ≥ π 4 π All together, these three functions are combined to form the function f   (ϕ ) =  f fσ  f  circle circle circle (ϕ ) + σ ⋅ [ f (ϕ ) (ϕ ) + σ ⋅ [ f box (ϕ ) − f circle (ϕ )] (ϕ )] for for for circle (ϕ ) − f r hom b σ >0 σ =0 σ a_max_upper_limit) printf(" [WARNING: a_max > a_max_upper_limit]"); printf("\n\n"); return 0; } /* -------------------------------------------------------------------------- */ Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG TMC428 DATASHEET (v. 2.02 / April 26 , 2006) th 54 Revision History Version Date Comment First complete version published in printed form Version updated based on customer feed back Version published on www.trinamic.com and TECHlibCD Changed to font Arial, numbering added to headings, revision history added additional hints concerning motion parameters units and signed representation and concerning signal polarities (see section 2.5, page 5), hint added concerning SPI timing of µC interface section 6.2on page 8, hint concerning power-on reset initialization values added near Table 7-2 on page 15, LP bit position corrected @ Table 7-2 on page 15 and Table 8-5 on page 24, limit parameter a_max_upper_limit similar to a_max_lower_limit added as new subsection (see page 17), interrupt register index (hint within text, section 8.13, page 24) corrected to IDX=%1011, additional statements concerning the functional difference of stop switch and reference switch in context of parameter dx_ref_tolerance section 8.15 on page 27, hints concerning MSB order concerning sending and receiving via the µC SPI interface, hints concerning the functional difference between stop switch and reference switch, description concerning latching the position (under control of REF_RnL bit) corrected is section 8.16 on page 27, function of the CDGW status bit explained in more detail concerning datagram_high_word and datagram_low_word (section 9.1 on page 27) and cover_datagram (section 9.3 on page 28), correction of maximum value of clk2_div and formula to calculate the datagram frequency f_datagram[Hz] added to section 9.7 on page 29, numbering within table of table concerning Table 9-2: Global parameter LSMD (last stepper motor driver) on page 30 corrected, Figure 11-1 on page 36 added to outline the driver chain configuration principle, imaginary example for Stepper Motor Driver Datagram Configuration (see page 38) changed to real example for the TMC236 / TMC239 / TMC246 / TMC249 family, section 12.1 (page 41) concerning indexing the wave LUT added, optional capacitor Copt added to drawing Figure 16-1on page 49, calculation of the number of steps during acceleration added to section 8.14, Table 18-1 on page 51 temperature ranges completed, example 'pmulpdiv.c' on page 53 for calculation of p_mul & p_div replaced by a more efficient one Changes concerning new company TRINAMIC Motion Control GmbH & Co. KG One of twice repeated phrase “A write to one of these …” removed within section 9.1 on page 27, equation “| ramp_div and pulse_div |