EVB90393

MLX90393 Getting Started Guide Abstract This guide was written with the goal of describing the basic setup and troubleshooting steps required for integrating the MLX90393 Triaxis™ device in an application. A simple rotary sensing application is used as an example. Applicable Applications All rotary, linear, and joystick applications using the MLX90393. Recommended Tools and Resources MLX90393 Datasheet Oscilloscope or I2C->PC adaptor with I2C decoding MLX90393 EVB (evaluation board) and MBED LPC1768 board Convention, Acronyms, and Abbreviations Number Format and Text Values in hexadecimal are shown with a preceding “0x”. For example: 0x12 is decimal 18. Binary values are shown with a preceding “0b”. For example: 0b10010 is decimal 18. Textual descriptions are shown in this format Code examples are shown in this format Warnings and cautions are shown in this format Acronyms SDA = Serial Data Line SCK = Serial Clock Line VDD = Analog Supply VDD_IO = Digital Supply Rev 004 MSb = Most Significant Bit LSb = Least Significant Bit MSB = Most Significant Byte LSB = Least Significant Byte Page 1 of 23 Jun-15 MLX90393 Getting Started Guide Table of Contents Abstract..............................................................................................................................................................................1 Applicable Applications......................................................................................................................................................1 Recommended Tools and Resources .................................................................................................................................1 Convention, Acronyms, and Abbreviations .......................................................................................................................1 Number Format and Text ..............................................................................................................................................1 Acronyms .......................................................................................................................................................................1 Table of Contents ...............................................................................................................................................................2 Pinout.................................................................................................................................................................................4 Axis Definition ....................................................................................................................................................................5 Practical getting started .....................................................................................................................................................6 Practical getting started guide ......................................................................................................................................7 MLX90393 interface library for mbed ...........................................................................................................................7 CherryStone soft-and firmware releases & compatibility .............................................................................................8 Communication .................................................................................................................................................................9 2 I C Protocol ....................................................................................................................................................................9 SPI Protocol .................................................................................................................................................................10 Memory Model ................................................................................................................................................................11 HALLCONF ...................................................................................................................................................................11 GAIN_SEL .....................................................................................................................................................................11 Z_SERIES ......................................................................................................................................................................11 BURST_DATA_RATE .....................................................................................................................................................11 BURST_SEL ...................................................................................................................................................................12 TCMP_EN .....................................................................................................................................................................12 EXT_TRIG .....................................................................................................................................................................12 WOC_DIFF ...................................................................................................................................................................12 COMM_MODE .............................................................................................................................................................12 TRIG_INT_SEL ..............................................................................................................................................................12 OSR ..............................................................................................................................................................................12 DIG_FILT ......................................................................................................................................................................12 RES_XYZ .......................................................................................................................................................................12 OSR2 ............................................................................................................................................................................13 SENS_TC_LT & SENS_TC_HT ........................................................................................................................................13 OFFSET_X, OFFSET_Y & OFFSET_Z ...............................................................................................................................13 WOXY_THRESHOLD, WOZ_THRESHOLD & WOT_THRESHOLD....................................................................................13 Address 10-31 ..............................................................................................................................................................13 Key Commands ................................................................................................................................................................14 Rev 004 Page 2 of 23 Jun-15 MLX90393 Getting Started Guide CONTROL COMMANDS ................................................................................................................................................14 Exit (EX)........................................................................................................................................................................14 Reset (RT) ....................................................................................................................................................................15 MEMORY COMMANDS ................................................................................................................................................15 Memory Store (HS) ......................................................................................................................................................15 Memory Recall (HR).....................................................................................................................................................15 Read Register (RR) .......................................................................................................................................................15 Write Register (WR).....................................................................................................................................................15 MEASUREMENT COMMANDS .....................................................................................................................................15 Start Burst Mode (SB) ..................................................................................................................................................15 Single Measurement (SM) ...........................................................................................................................................16 Read Measurement (RM) ............................................................................................................................................16 Start Wake-up on Change (SWOC) ..............................................................................................................................16 Application specific ..........................................................................................................................................................17 Resolution....................................................................................................................................................................17 Calculation of conversion time ....................................................................................................................................17 Sensitivity .........................................................................................................................................................................18 Available hardware (EVB) ............................................................................................................................................19 Example #1: Rotary Application .......................................................................................................................................20 Magnetic Configuration ...............................................................................................................................................20 Suggested EEPROM Configuration ..............................................................................................................................20 Rotary Code Example ..................................................................................................................................................21 Rev 004 Page 3 of 23 Jun-15 MLX90393 Getting Started Guide Pinout NC NC A1 A0 The pinout for the MLX90393 is below. VSS VDDIO NC INT/ TRG MLX90393 NC SDA/ MOSI SCLK NC CS MISO INT VDD PIN 1 Figure 1: Pinout Pin Number 1 Pin Function Data ready signal output pin, active high (DRDY flag) Chip select, used when communicating in SPI mode 2 CS Pull high when in I2C mode 3 SCLK Serial clock for both SPI and I2C mode 4, 9, 10, 14, 16 NC 5 SDA/MOSI Data input pin in SPI mode, data input/output pin in I2C mode 6 MISO Data output pin in SPI mode 7 INT/TRIG Trigger pin, can be used to start measurement 8 VDDIO Power supply for digital 11 A1 Bit 1 of the 7-bit I2C address (0 0 0 1 1 A1 A0) 12 A0 Bit 0 of the 7-bit I2C address (0 0 0 1 1 A1 A0) 13 VSS Ground 15 Vdd Power supply Rev 004 Pin Name INT Page 4 of 23 Jun-15 MLX90393 Getting Started Guide Axis Definition The axes of the MLX90393 are defined in the datasheet and are shown below. Figure 2: MLX90393 QFN Axis Definitions Rev 004 Page 5 of 23 Jun-15 MLX90393 Getting Started Guide Practical getting started Legend: Software Firmware Communication Application Diagram I2C Getting Started in practice Application Diagram SPI Host PC/ Laptop · Download LabVIEW Run-Time Engine (12.0) à install · Download NI-VISA Driver (5.0.3) à install · Download MBED USB-driver à install (connect mbed) Mbed LPC1768 · Download MBED -Firmware à upload to mbed and reset MLX90393 · Make physical connections between PC,MBED and MLX90393 MBED USBdriver CherryStone.exe USB Physical USB-cable Firmware (SPI or I2C) 9039X .h 9039X .cpp Physical connection cables (I2C) OR USB SPI Main.cpp SPI NI-VISA Driver I2C LabVIEW Run-Time Engine I2C Host PC/Laptop · Download CherryStone.exe à install and run Physical connection cables (SPI) Host PC / Laptop MLX9039X MBED LPC1768 Implementation / Installation sequence CherryStone.exe LabVIEW Run-Time Engine NI-VISA Driver Rev 004 Firmware (SPI or I2C) MBED Driver MLX9039X SPI OR I2C - protocol Page 6 of 23 Jun-15 MLX90393 Getting Started Guide Practical getting started guide 1. NI LabView Runtime Engine A first step before installing the CherryStone executable is installing LabVIEW Run-Time Engine 12.0. This software can be downloaded directly from National Instruments website. 32-bit version: Click here http://www.ni.com/download/labview-run-time-engine-2012/3433/en/ 2. NI VISA-driver Visa Driver: Click here http://www.ni.com/download/ni-visa-run-time-engine-5.0.3/2257/en 3. MBED driver Make sure your mbed is connected while executing this step Mbed Driver: Click here http://developer.mbed.org/media/downloads/drivers/mbedWinSerial_16466.exe 4. CherryStone Software Executable CherryStone (= the interface program, refer to diagram shown earlier in this document): Click here 5. MBED firmware MBED SPI firmware: Click here 2 MBED I C firmware: Click here Upload the firmware to mbed: · · · Connect your mbed to your PC/laptop - a new drive called “MBED” should appear. Download the firmware from the Melexis website (either SPI, or I2C) and drag and drop the file directly into the drive”. Once the bin-file is uploaded, the mbed must be reset by pressing the push button at the center of the mbed. MLX90393 interface library for mbed Sample code and a complete library holding all MLX90393’s functions are written for mbed and can be downloaded from www.mbed.org/teams/melexis or directly from our website The MBED used at Melexis is the LPC1768. Please note that the firmware BIN files made available have been compiled for this specific MBED hardware. When using other MBED devices, or other microcontrollers in general, the source code is recommended as a starting point for software development. Rev 004 Page 7 of 23 Jun-15 MLX90393 Getting Started Guide CherryStone soft-and firmware releases & compatibility Date January 2015 Rev 004 CherryStone.exe CherryStone.bin CherryStone 3 CherryStone3_I2C(SDA = p9, SCL = p10, A1=p21, A0=p22).bin CherryStone3_SPI(MOSI =p5, MISO = p6, CLK= p7, CS=p8).bin Page 8 of 23 Jun-15 MLX90393 Getting Started Guide Communication The MLX90393 can be used with either an SPI or an I2C bus. The use of both protocols will be explained in the next sections. This user guide gives a brief introduction to our user interface tool for quick ‘plug and play’ solutions that enables you to communicate with the MLX90393 without having to make the effort of implementing the communication protocol yourself. I2C Protocol 2 One initial hurdle with starting work with the MLX90393 is configuring the I C bus correctly. The clock frequency can 2 be set between 10kHz (low-speed mode), 100kHz(standard mode), 400kHz (Fast mode). Every I C device on the bus 2 must also be assigned an address. The two LSB’s of the MLX90393 I C address can be selected via the A0 and A1 pins allowing for four different addresses. In this document it is assumed that the A0 and A1 pins are shorted to ground. 2 This results in an I C address of 0x19 (for MBED, in other environments this might be defined in another way). 2 The7 bit I C address in MBED is defined as follows as a byte: 7 bit I2C address 0 0 0 1 1 A1 A0 1 Defined by Melexis Defined by connecting pins A0 and A1 to GND/ VDD R/W bit set 2 Figure 3: MBED I C address definition The orange section is set in the NVRAM of the IC, the yellow section depends on how pins A0 and A1 are connected. The last bit should be set for the MBED, no matter if one reads or write to the IC. The MBED will send on the bus the correct R/W bit automatically. The MLX90393 operates on a command / response configuration and can be broken down into two sequences: Command Write and Response Read. Command Write: To initiate a communication sequence the master addresses the slave with the write bit set. If the MLX90393 recognizes the address it responds with an ACK. The master then issues the command to the MLX90393. If accepted, the MLX90393 responds with another ACK. SCL 1 SDA 2 3 4 5 I2C_ADDR[6:0] 6 7 8 9 W ACK 1 2 3 4 5 COMMAND[7:0] 6 7 8 9 ACK S 2 Figure 4: Sending an I C command Response Read: To read back the response the master addresses the MLX90393 with the R bit set. The master then sends enough clock pulses to clock out all the required data bytes. The number of data bytes depends on the command transmitted Rev 004 Page 9 of 23 Jun-15 MLX90393 Getting Started Guide and can range from zero (eg: NOP message) to eight (eg: measurement with all axes, temp, and a status byte). The number of data bytes is indicated in the status byte which is always the first byte read out from the MLX90393. SCL 1 2 SDA 3 4 5 6 7 I2C_ADDR[6:0] 8 9 R ACK 1 2 3 4 5 6 7 8 STATUS_BYTE[7:0] 9 ACK Sr P 2 Figure 5: I C readback of status byte Note: Failure to readdress the slave after the Command Write will result in the transaction failing. SPI Protocol One initial hurdle with starting work with the MLX90393 is configuring the SPI bus correctly. The chip can handle clock frequencies up to 10MHz. The SPI communication is implemented in a half-duplex way, showing high 2 similarities with the I C communication. Addressing on the bus is done through the \CS instead of physical addresses. Both three- and four-wire SPI is possible (three wire by shorting the MISO and MOSI). SPI mode 3 is implemented: CPHA=1 (data changed on leading edge and captured on trailing edge, and CPOL=1 (high level is inactive state). The Chip Select line is active-low. The MLX90393 operates on a command / response configuration and both are sequentially done in one go in SPI. The communication is also bundled in bytes, equally MSB first and MSByte first. A command can of course consist of more than 1 byte as can the response be from the MLX90393 in the form of multiple bytes after the status byte. Figure 6 shows an example of an SPI command being followed by the readback of the status byte. /CS SCL 1 MOSI 2 3 4 5 6 7 8 1 COMMAND[7:0] MISO 2 3 4 5 6 7 8 X (4-wire SPI) or Z (3-wire SPI) Z (3 & 4-wire SPI) STATUS_BYTE[7:0] ADD NADD Figure 6: SPI example Rev 004 Page 10 of 23 Jun-15 MLX90393 Getting Started Guide Memory Model As the code example will be modifying the register contents it is useful to review the memory model of the MLX90393. It operates with a dual memory model consisting of volatile and nonvolatile areas. During operating conditions the values in the volatile memory are used and are loaded from nonvolatile memory at power up or when a recall command is issued. It is necessary to know that if the write register command is issued this affects the volatile memory only. A store command is needed to permanently store the modifications. Refer to the datasheet for more details. The first 32 addresses are programmable by the user. VOLATILE MEMORY NON-VOLATILE MEMORY CUSTOMER AREA CUSTOMER AREA STORE (HS) RECALL (HR) MELEXIS AREA RR MELEXIS AREA WR Figure 7: Memory model 15 0 1 TRIG_INT_SEL 2 3 4 5 6 7 8 9 14 13 COMM_MODE RESERVED 12 11 RESERVED_LOW WOC_DIFF EXT_TRIG OSR2 SENS_TC_HT 10 TCMP_EN 9 8 7 Z_SERIES BURST_SEL RES_XYZ 6 5 GAIN_SEL 4 3 2 1 0 HALLCONF BURST_DATA_RATE DIG_FILT SENS_TC_LT OSR OFFSET_X OFFSET_Y OFFSET_Z WOXY_THRESHOLD WOZ_THRESHOLD WOT_THRESHOLD Figure 8: Memory map of customer area HALLCONF Spinning and chopping rate adjustment. HALLCONF[3:2] defines the duration of one Hall plate spinning phase in clock cycles: #clocks/spinning_phase = 8 * HALLCONF[3:2] 2 . Default this value is 3. HALLCONF[1:0] defines the number of amplifier chopping periods inside one spinning phase: HALLCONF[1:0] #chopping_periods/spinning_phase = 2 . Default this value is 0. The default HALLCONF is 0xC. GAIN_SEL Selection of the gain, adjustable from 0 to 7. See sensitivity table for sensitivity of the IC in LSB/G for each setting of the gain and the resolution. Z_SERIES Connection of the Hall plates for Z-axis measurements. Recommended setting: 0x0. BURST_DATA_RATE This parameter controls the data rate in burst mode and in WOC mode. The rate is defined as the time between the end of one measurement and the start of a new measurement, regardless of the fact if the data is read out or not. A Rev 004 Page 11 of 23 Jun-15 MLX90393 Getting Started Guide value of 0x0 means a continuous burst mode, other value encode as follows: interval = 20ms * BURST_DATA_RATE. The max is 0x3F, corresponding to 1260ms. This interval can be observed by looking at the DRDY flag. BURST_SEL This parameter determines the measurements (X, Y, Z and Temp, or any combination of them) to be performed in the case that the SB or SWOC command did not specify the measurements. The bit order is (from MSB to LSB): ZYXT. TCMP_EN Enables the temperature compensation. Please refer to the application note on the temperature compensation for more info. EXT_TRIG When this bit is set, the external pin INT/TRIG can be used to start a measurement. This only works when TRIG_INT_SEL is not set (digital input). Otherwise, changes at this pin will be ignored. The axes to be measured are specified by BURST_SEL. WOC_DIFF Absolute or derivative WOC mode: If 0, an absolute mode is used. Measurements are compared to the first measurements; If 1, a relative mode is used. Measurements are compared to the previous ones. COMM_MODE Defines the communication mode. If it is 0x0 or 0x1, the IC can be used both by I2C and SPI. If 0x2, only SPI can be used and if 0x3 only I2C can be used. TRIG_INT_SEL Selects the function of the INT/TRIG pin. When set, the pin is used as digital output, otherwise it is an input. OSR Defines the oversampling rate of the ADC decimation filter for magnetic measurements. OSR_ADC = 64 * 2 will directly impact the measurement time for magnetic measurements. Note: The chip will not work properly with the following combinations: OSR=0 and DIG_FILT=0, OSR=0 and DIG_FILT=1 and OSR=1 and DIG_FILT=0 OSR . This DIG_FILT DIG_FILT A control for the digital filter. An averaging over a certain amount (2 ) will be done. This will directly impact the measurement time for magnetic measurements. Note: The chip will not work properly with the following combinations: OSR=0 and DIG_FILT=0, OSR=0 and DIG_FILT=1 and OSR=1 and DIG_FILT=0 RES_XYZ This 6 bit parameter consists out of three parts, one for each axis. The two MSBs act on the Z-axis, the 2 LSBs on the X-axis and the middle 2 bits on the Y-axis. Internally each magnetic measurement is 19 bits long. On the output, only 16 bits can be read out. This parameter selects for each axis which 16 bits to read out. Please refer to section Error! eference source not found. for further detailed information. Rev 004 Page 12 of 23 Jun-15 MLX90393 Getting Started Guide OSR2 Defines the oversampling rate of the ADC decimation filter for a temperature measurement. OSR_ADC = 64 * 2 This will directly impact the measurement time for the temperature measurement. OSR . SENS_TC_LT & SENS_TC_HT These parameters are used for the temperature compensation for the sensitivity drift of the Hall elements. SENS_TC_HT is the parameter for temperatures above 35 degC, SENS_TC_LT is the parameter for temperatures below 35 degC. Please refer to the application note on the temperature compensation for more info. These values can be blindly programmed to the values given in this document (if not already programmed). OFFSET_X, OFFSET_Y & OFFSET_Z These parameters are used to compensate the offset in case the temperature compensation is enabled. They are not used with TCMP disabled. Please refer to the application note on the temperature compensation for more info. These values can be blindly programmed to the values given in this document (if not already programmed). WOXY_THRESHOLD, WOZ_THRESHOLD & WOT_THRESHOLD Defines the wake up thresholds on X, Y, Z axis or on temperature. The resolution of the temperature sensor is 45.2LSB/K. Address 10-31 Address 10 to 31 are free to use by the customer. For example traceability information could be stored in here. Rev 004 Page 13 of 23 Jun-15 MLX90393 Getting Started Guide Key Commands Table 1 shows an overview of all commands possible with the MLX90393. The amount of bytes to be sent and read back is different for each command. In case more bytes are needed, first byte #1 is sent, then byte #2 and so on. Table 1: Commands overview Command Symbol CMD byte #1 CMD byte #2 CMD byte #3 CMD byte #4 # bytes to read back EXit EX 1000 0000 - - - 1 (status) Start Burst mode SB 0001 zyxt - - - 1 (status) Start Wake-up On Change SWOC 0010 zyxt - - - 1 (status) Start Measurement (polling mode) SM 0011 zyxt - - - 1 (status) Read Measurement RM 0100 zyxt - - - 1 (status) + 2*[z+x+y+t] (data) Read from a Register RR 0101 0000 A[5:0]