KMA199

KMA199 Programmable angle sensor Rev. 01 — 26 April 2010 Product data sheet 1. Product profile 1.1 General description The KMA199 is a magnetic angle sensor system. The MagnetoResistive (MR) sensor bridges and the mixed signal Integrated Circuit (IC) are integrated into a single package. This angular measurement system KMA199 is pre-programmed, pre-calibrated and therefore, ready to use. The KMA199 allows user specific adjustments of angular range, zero angle and clamping voltages. The settings are stored permanently in an Electrically Erasable Programmable Read-Only Memory (EEPROM). 1.2 Features and benefits High precision sensor for magnetic angular measurement Automotive qualified in accordance with AEC-Q100 Programmable user adjustments, including zero angle and angular range Fail-safe EEPROM Independent from the magnetic field strength above 35 kA/m User-programmable 32-bit identifier Ready to use Ratiometric analog output voltage Single package sensor system High temperature range up to 160 °C Built-in transient protection Programming via One-Wire Interface (OWI) Magnet-loss and power-loss detection Factory calibrated NXP Semiconductors KMA199 Programmable angle sensor 2. Pinning information Table 1. Pin 1 2 3 VDD GND OUT/DATA Pinning Description supply voltage ground analog output or data interface Simplified outline Symbol 1 2 3 3. Ordering information Table 2. Ordering information Package Name KMA199 Description plastic single-ended multi-chip package; 6 interconnections; 3 in-line leads Version SOT880 Type number KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 2 of 36 xxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x xxxxxxxxxxxxxx xxxxxxxxxx xxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxx xx xxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxx xxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxx xxxxxx xx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxx xxxxx x x Product data sheet Rev. 01 — 26 April 2010 3 of 36 KMA199_1 4. Functional diagram NXP Semiconductors VDDE Vref Iref VDDS All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. VDD VDDS REGULATOR VDDA REGULATOR VDDD REGULATOR LOGIC POWER-ON RESET VSSE POWER LOST Cblock VSSE VSINP MUX VSINN VCOSP 2 AMPLIFIER 2 A D D A OUTPUT BUFFER VO OUT/ DATA VCOSN VSSS TP0 TP1 TP2 POWER LOST DIGITAL FILTER OFFSET AND CORRECTION AVERAGING ANGULAR RANGE ADJUSTMENT TEST CONTROL Q_PUMP ARRAY CORDIC ALGORITHM OFFSET CALCULATION ONE-WIRE INTERFACE OSC EEPROM DIGITAL BLOCKS (LOGIC) VSSE GND magnetoresistive sensor bridges signal conditioning integrated circuit internal protection diodes 008aaa233 Programmable angle sensor KMA199 Fig 1. Functional diagram of KMA199 NXP Semiconductors KMA199 Programmable angle sensor 5. Functional description The KMA199 amplifies two orthogonal differential signals which are delivered by MR sensor bridges and converts them into the digital domain. The angle is calculated using the COordinate Rotation DIgital Computer (CORDIC) algorithm. After a digital-to-analog conversion the analog signal is provided to the output. Thus, the output is a linear representation of the angular value. Zero angle, clamping voltages and angular range are programmable. In addition, two 16-bit registers are available for customer purposes, like sample identification. The KMA199 comprises a Cyclic Redundancy Check (CRC) and an Error Detection and Correction (EDC) supervision, as well as a magnet-loss detection to ensure a fail-safe operation. A power-loss detection circuit pulls the analog output to the remaining supply line, if either the supply voltage or the ground line is interrupted. After multiplexing the two MR Wheatstone bridge signals and their successive amplification, the signal is converted into the digital domain by an Analog-to-Digital Converter (ADC). Further processing is done within an on-chip state machine. This includes offset cancellation, calculation of the mechanical angle using the CORDIC algorithm, as well as zero angle and angular range adjustment. The internal Digital-to-Analog Converter (DAC) and the analog output stage are used for conversion of the angle information into an analog output voltage, which is ratiometric to the supply voltage. The configuration parameters are stored in an user-programmable EEPROM. The OWI (accessible using pin OUT/DATA) is used for accessing the memory. 5.1 Angular measurement directions The differential signals of the MR sensor bridges depend only on the direction of the external magnetic field strength Hext, which is applied parallel to the plane of the sensor. In order to obtain a correct output signal, the minimum saturation field strength has to be exceeded. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 4 of 36 NXP Semiconductors KMA199 Programmable angle sensor α Hext 001aag741 Fig 2. Angular measurement directions Since the Anisotropic MR (AMR) effect is periodic over 180°, the sensor output is also 180°-periodic, where the angle is calculated relative to a freely programmable zero angle. The dashed line indicates the mechanical zero degree position. 6. Analog output The KMA199 provides one analog output signal on pin OUT/DATA. The measured angle α is converted linearly into a value, which is ratiometric to the supply voltage VDD. Either a positive or a negative slope is provided for this purpose. The following table describes the analog output behavior for a positive slope. If for example, a magnetic field angle, above the programmed maximum angle αmax, but below the clamp switch angle αsw(CL) is applied to the sensor, then analog output is set to the upper clamping voltage. If the magnetic field angle is larger than the clamp switch angle, the analog output switches from upper to lower clamping voltage. In the case of a negative slope, the clamping voltages are changed. Table 3. Analog output behavior for a positive slope Analog output V(CL)u V(CL)l Magnetic field angle αmax < α < αsw(CL) αsw(CL) < α < αref + 180° The analog output voltage range codes both angular and diagnostic information. A valid angle value is between the upper and lower clamping voltage. If the analog output is in the diagnostic range, that is below 4 %VDD or above 96 %VDD, an error condition has been detected. The analog output repeats every 180°. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 5 of 36 NXP Semiconductors KMA199 Programmable angle sensor VO (%VDD) V(CL)u αrng V(CL)I 0 αref α (deg) αmax 180 αsw(CL) αref + 180° 001aag811 αmax = αref + αrng Fig 3. Characteristic of the analog output 7. Diagnostic features The KMA199 provides four diagnostic features: 7.1 EEPROM CRC and EDC supervision The KMA199 system includes a supervision of the programmed data. At power-on, a CRC of the EEPROM is performed. Furthermore the EEPROM is protected against bit errors. Every 16-bit data word is saved internally as a 22-bit word for this purpose. The protection logic corrects any single-bit error in a data word, while the sensor continues in normal operation mode. Multiple bit errors per word will be detected and switches the device into diagnostic mode. 7.2 Magnet-loss detection If the applied magnetic field strength is not sufficient, the KMA199 raises a diagnostic condition. In order to enter the diagnostic mode, due to EEPROM CRC or magnet-loss detection, the device can be programmed into active diagnostic mode, where the output is driven below 4 %VDD or above 96 %VDD. 7.3 Power-loss detection The power-loss detection circuits enable the detection of an interrupted supply or ground line of the KMA199. In the case of a power-loss condition, two internal switches in sensor are closed, connecting the pin of the analog output with the supply voltage and the ground pins. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 6 of 36 NXP Semiconductors KMA199 Programmable angle sensor KMA199 ZO(pl) VDD OUT/DATA ZO(pl) GND 008aaa234 Fig 4. Equivalent output circuit in case of a power-loss condition Table 4 shows the resulting output voltage depending on the error case and the load resistance. Table 4. RL > 5 kΩ Power-loss behavior Supply voltage lost VO ≤ 4 %VDD Ground lost VO ≥ 96 %VDD Load resistance 7.4 Low supply voltage detection If the supply voltage is below the switch-off threshold voltage, a status bit is set. Table 5 describes the behavior of the analog output at different supply voltages. Table 5. Supply voltage behavior Description the output drives an active LOW, but the switches of the power-loss detection circuits are not fully opened and set the output to a level between ground and half the supply voltage all modules begin to work and the power-on reset is active Analog output actively driven output to a voltage level between ground and half the supply voltage Voltage range 0 V to ≈ 1.5 V ≈ 1.5 V to VPOR VPOR to Vth(on) or Vth(off) diagnostics at LOW level all modules begin to work and the digital part is EEPROM defined diagnostic initialized level analog output of the measured angle without the specified accuracy Vth(on) or Vth(off) to analog output is switched on after power-on 4.5 V time and represents the measured angle 4.5 V to 5.5 V normal operation where the sensor works with analog output of the the specified accuracy measured angle KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 7 of 36 NXP Semiconductors KMA199 Programmable angle sensor 8. Limiting values Table 6. Limiting values In accordance with the Absolute Maximum Rating System (IEC 60134). Symbol VDD VO Ir Tamb Tamb(pr) Tstg EEPROM tret(D) data retention time Tamb = 50 °C Tamb(pr) = 70 °C 17 100 year cycle Nendu(W_ER) write or erase endurance [1] [2] Time until sensor environment is initialized. The maximum value of the output voltage is 5.7 V. Parameter supply voltage Conditions tinit < 200 h [1] [2] Min −0.3 −0.3 −40 10 −40 Max +5.7 6.0 150 +160 70 +125 Unit V V mA °C °C °C output voltage reverse current ambient temperature programming ambient temperature storage temperature Tamb < 70 °C VDD + 0.3 V 9. Recommended operating conditions Table 7. Operating conditions In a homogenous magnetic field. Symbol VDD Tamb Tamb(pr) CL Cblock RL Hext [1] [2] [3] [4] Parameter supply voltage ambient temperature programming ambient temperature load capacitance blocking capacitance load resistance external magnetic field strength Conditions [1] Min 4.5 −40 10 [2] [3] [4] Typ 5.0 - Max 5.5 70 22 ∞ ∞ - Unit V °C nF nF kΩ kA/m +160 °C 0 75 5 35 Normal operating mode. Between ground and analog output, as close as possible to the package for improved electromagnetic immunity. Between ground and supply voltage, as close as possible to the package and with a low equivalent series resistance. Power-loss detection is only possible with a load resistance within the specified range connected to the supply or ground line. 10. Thermal characteristics Table 8. Symbol Rth(j-a) Thermal characteristics Parameter thermal resistance from junction to ambient Conditions Typ 120 Unit K/W KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 8 of 36 NXP Semiconductors KMA199 Programmable angle sensor 11. Characteristics Table 9. Supply current Characteristics are valid for the operating conditions, as specified in Section 9. Symbol IDD [1] [2] Parameter supply current Conditions [1][2] Min 5 Typ - Max 10 Unit mA Normal operating mode. Without load current at the analog output. Table 10. Power-on reset Characteristics are valid for the operating conditions, as specified in Section 9. Symbol Vth(on) Vth(off) Vhys VPOR Parameter switch-on threshold voltage switch-off threshold voltage hysteresis voltage power-on reset voltage Conditions analog output switches on, if VDD > Vth(on) analog output switches off, if VDD < Vth(off) Vhys = Vth(on) − Vth(off) IC is initialized Min 4.00 0.1 2.4 Typ 4.30 4.20 Max 4.45 4.30 0.4 3.3 Unit V V V V Table 11. System performance Characteristics are valid for the operating conditions, as specified in Section 9. Symbol αres αmax αref VO(nom) VO(udr) VO(ldr) V(CL)u V(CL)l ΔV(CL) IO Vn(o)(RMS) Δφlin Parameter angle resolution maximum angle reference angle nominal output voltage upper diagnostic range output voltage lower diagnostic range output voltage upper clamping voltage lower clamping voltage clamping voltage variation output current RMS output noise voltage linearity error deviation from programmed value normal operation mode; operating as sink or source equivalent power noise temperature range −40 °C to +160 °C temperature range −40 °C to +140 °C Δφtemp temperature drift error temperature range −40 °C to +160 °C temperature range −40 °C to +140 °C [5] [5][6] Conditions [1] Min 5 0 5 [3] [2] Typ 0.4 - Max 0.04 180 180 95 100 4 95 30.5 +0.3 2 2.5 +1.2 +1 0.8 0.65 Unit deg deg deg %VDD %VDD %VDD %VDD %VDD %VDD mA mV deg deg deg deg programmable angular range for V(CL)u − V(CL)l ≥ 80 %VDD programmable zero angle at full supply operating range [2] 96 0 40 5 −0.3 −1.2 −1 - [3] [4] [4] [5][6] [1][5][6] [7] [1][5][6] [7] KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 9 of 36 NXP Semiconductors KMA199 Programmable angle sensor Table 11. System performance …continued Characteristics are valid for the operating conditions, as specified in Section 9. Symbol Δφtemp⏐RT Parameter temperature drift error at room temperature Conditions temperature range −40 °C to +160 °C temperature range −40 °C to +140 °C Δφhys Δφμlin Δφang hysteresis error microlinearity error angular error referred to input referred to input temperature range −40 °C to +160 °C temperature range −40 °C to +140 °C mang ZO(pl) slope of angular error power-loss output impedance impedance to remaining supply line in case of lost supply voltage or lost ground [6][7][8] Min −0.1 −1.35 −1.1 - Typ - Max 0.65 0.55 0.09 +0.1 +1.35 +1.1 0.04 210 Unit deg deg deg deg deg deg deg/deg Ω [6][7][8] [5][6] [5][6] [5][6][9] [5][6][9] [5][6][9] [1] [2] [3] [4] [5] [6] [7] [8] [9] At a nominal output voltage between 5 %VDD and 95 %VDD and a maximum angle of αmax = 180°. In steps of resolution < 0.022°. Activation is dependent on the programmed diagnostic mode. In steps of 0.02 %VDD. At a low-pass filtered analog output with a cut-off frequency of 0.7 kHz. Definition of errors is given in Section 12. Based on a 3σ standard deviation. Room temperature is given for an ambient temperature of 25 °C. Graph of angular error is shown in Figure 5. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 10 of 36 NXP Semiconductors KMA199 Programmable angle sensor 1.40 1.35 |Δφang| (deg) 1.10 (1) (2) 0.75 0.65 0 −20 −16 −12.25 −1 0 1 12.25 20 16 α1 − α0 (deg) 001aal765 (1) −40 °C to +160 °C. (2) −40 °C to +140 °C. Fig 5. Envelope curve for the magnitude of angular error Table 12. Dynamics Characteristics are valid for the operating conditions, as specified in Section 9. Symbol ton fupd ts Parameter turn-on time update frequency settling time after an ideal mechanical angle step of 45°, until 90 % of the final value is reached; CL = 5 nF Conditions until first valid result [1] Min 2 - Typ 3.125 - Max 5 1.8 Unit ms kHz ms tcmd(ent) [1] enter command mode time after power on 16 - 26 ms After reaching the power-on threshold voltage. Table 13. Digital interface Characteristics are valid for the operating conditions, as specified in Section 9. Symbol VIH VIL VOH VOL Iod tstart KMA199_1 Parameter HIGH-level input voltage LOW-level input voltage HIGH-level output voltage LOW-level output voltage overdrive current start time Conditions Min 80 - Typ - Max 20 20 20 - Unit %VDD %VDD %VDD %VDD mA μs IO = 2 mA IO = 2 mA absolute value for overdriving the output buffer LOW level before rising edge 80 5 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 11 of 36 NXP Semiconductors KMA199 Programmable angle sensor Table 13. Digital interface …continued Characteristics are valid for the operating conditions, as specified in Section 9. Symbol tstop Tbit Parameter stop time bit period Conditions HIGH level before falling edge minimum period may be limited by the load capacitance deviation between received clock and sent clock Min 5 10 Typ Max 100 Unit μs μs ΔTbit tw0 tw1 tto ttko(slv) ttko(mas) tprog tcp bit period deviation pulse width 0 pulse width 1 time-out time slave takeover time master takeover time programming time charge pump time 0.8Tbit 0.175Tbit 0.625Tbit 1Tbit 0.25Tbit 0.75Tbit - 1.2Tbit 0.375Tbit 0.825Tbit 220 5 0.5Tbit - s s s μs μs s ms ms digital communication reset guaranteed after maximum tto duration of LOW level for slave takeover duration of LOW level for master takeover for a single EEPROM address waiting time after enabling the EEPROM charge pump clock 1 0Tbit 20 1 12. Definition of errors 12.1 General Angular measurement errors by the KMA199 result from linearity errors, temperature drift errors and hysteresis errors. Figure 6 shows the output signal of an ideal sensor, where the measured angle φmeas corresponds ideally to the magnetic field angle α. This curve will further be denoted as angle reference line φref(α) with a slope of 0.5 %VDD/deg. φmeas (deg) φref(α) 180 α (deg) 001aag812 Fig 6. Definition of the reference line The angular range is set to αmax = 180° and the clamping voltages are programmed to V(CL)l = 5 %VDD and V(CL)u = 95 %VDD for a valid definition of errors. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 12 of 36 NXP Semiconductors KMA199 Programmable angle sensor 12.2 Hysteresis error The hysteresis error Δφhys is defined as the maximum difference between the angles, given by the device output when performing a positive (clockwise) rotation and negative (counter clockwise) rotation over an angular range of 180°, measured at a constant temperature. φmeas (deg) Δφhys 180 α (deg) 001aag813 Fig 7. Definition of the hysteresis error Equation 1 gives the mathematical description for the hysteresis value Δφhys: Δφ hys(α) = φ meas(α → 180 °) – φ meas(α → 0 °) (1) 12.3 Linearity error The KMA199 output signal deviation from a best straight line φBSL, with the same slope as the reference line, is defined as linearity error. The magnetic field angle is varied at fixed temperatures for measurement of this linearity error. The output signal deviation from the best straight line at the given temperature is the linearity error Δφlin. It is a function of the magnetic field angle α and the temperature of the device Tamb. φmeas (deg) φBSL(α, Tamb) φref(α) Δφlin(α, Tamb) 180 α (deg) 001aag814 Fig 8. Definition of the linearity error KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 13 of 36 NXP Semiconductors KMA199 Programmable angle sensor 12.4 Microlinearity error The microlinearity error Δφμlin is the device output deviation from 1°, if the magnetic field angle α is changed by Δα = 1°. φmeas (deg) φref(α) Δφmeas = 1° + Δφμlin(α) Δα = 1° α (deg) 001aag815 Fig 9. Definition of the microlinearity error 12.5 Temperature drift error The temperature drift Δφtemp is defined as the envelope over the deviation of the angle versus the temperature range. It is considered as the pure thermal effect. φmeas (deg) Ty Tx Δφtemp 180 α (deg) 001aag816 Fig 10. Definition of the temperature drift error Equation 2 gives the mathematical description for temperature drift value Δφtemp: Δφ temp(α) = φ meas(α , T x) – φ meas(α , T y) with: Tx: temperature for maximum φmeas at angle α Ty: temperature for minimum φmeas at angle α (2) KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 14 of 36 NXP Semiconductors KMA199 Programmable angle sensor The deviation from the value at room temperature Δφtemp⏐RT describes the temperature drift of the angle, compared to the value, which the sensor provides at room temperature: Δφ temp with: TRT: room temperature (25 °C) RT(α , T amb) = φ meas(α , T amb) – φ meas(α , T RT) (3) 12.6 Angular error The angular error Δφang is the error of angle difference measured by the sensor, if the mechanical angle deviates from α0 to α1. Here α0 and α1 are arbitrary angles within the angular range. The angle measurement at α0 is the initially programmed reference angle, programmed by the customer at room temperature and zero hour upon production. The angle measurement at α1 is made at any temperature within the ambient temperature range: Δφ ang = ( φ meas(α 1 , T amb) – φ meas(α 0 , T RT) ) – ( α 1 – α 0 ) with: α0, α1: arbitrary mechanical angles within the angular range φmeas(α0, TRT): programmed angle at α0, TRT = 25 °C and zero hour upon production φmeas(α1, Tamb): angle measured by the sensor at α1 and any temperature within Tamb This error comprises non-linearity and temperature drift related to the room temperature. (4) |Δφang| mang |Δφang(peak)| |Δφμlin + Δφtemp|RT| −α* α0 − 1° α0 + 1° α0 +α* α1 001aal766 Fig 11. Definition of the angular error Figure 11 shows the envelope curve for the magnitude of angular error |Δφang| versus α1 for all angles α0 and all temperatures Tamb within the ambient temperature range. |Δφang| has its minimum, if α1 is in the range of ±1° around α0. Here only the microlinearity error Δφμlin and the temperature drift related to the room temperature |Δφtemp⏐RT| occurs. If α1 deviates from α0 by more than 1° in either direction, |Δφang| can increase with a gradient defined by slope mang. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 15 of 36 NXP Semiconductors KMA199 Programmable angle sensor Angular error can be expressed by Equation 5 to Equation 8: for |α1 − α0| ≤ 1° Δφ ang = Δφ μ lin + Δφ temp for 1° < |α1 − α0| < α* Δφ ang = Δφ μ lin + Δφ temp for |α1 − α0| ≥ α* Δφ ang = with: Δφ ang(peak) – Δφ μ lin + Δφ temp RT α∗ = ---------------------------------------------------------------------------------- + α 0 + 1 ° m ang (8) ( Δφ lin ) 2 + ( Δφ temp RT ) 2 RT RT (5) + m ang × ( α 1 – α 0 – 1 ° ) (6) (7) 13. Programming 13.1 General description The KMA199 provides an OWI to enable programming of the device which uses pin OUT/DATA bidirectionally. In general the device runs in analog output mode, the normal operating mode. This mode is configured by the embedded programming data and is started after a power-on reset once time ton has elapsed. In this mode, the magnetic field angle is converted into the corresponding output voltage. Command mode has to be entered to enable programming. In this mode, the customer can adjust all required parameters (for example zero angle and angular range) to meet the application requirements. After enabling the internal charge pump and waiting for tcp the data is stored in the EEPROM. After changing the contents of the EEPROM, the checksum must be recalculated and written (see Section 13.4). In order to enter the command mode, a specific command sequence must be send after a power-on reset and during the time slot tcmd(ent). The external source used to send the command sequence must overdrive the output buffer of the KMA199 (I > Iod). KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 16 of 36 NXP Semiconductors KMA199 Programmable angle sensor During communication, the KMA199 is always the slave and the external programming hardware is the master. Figure 12 illustrates the structure of the OWI data format. write IDLE START COMMAND DATA BYTE 1 DATA BYTE 2 STOP IDLE read IDLE START COMMAND HANDOVER DATA BYTE 1 DATA BYTE 2 TAKEOVER STOP IDLE 001aag742 Fig 12. OWI data format The master provides the start condition, which is a rising edge after a LOW level. Then a command byte which can be either a read or a write command is send. Depending on the command, the master or the slave has to send the data immediately after the command sequence. In the case of a read command, an additional handover or takeover bit is inserted before and after the data bytes. Each communication must be closed with a stop condition driven by the master. If the slave does not receive a rising edge for a time longer than tto, a time-out condition occurs. The bus is reset to the idle state and waits for a start condition and a new command. This can be used to synchronize the device regardless of the previous state. All communication is based on this structure (see Figure 12), even for entering the command mode. In this case a special write command is required, followed by the command sequence (two data bytes). The customer can access the EEPROM, CTRL1, TESTCTRL0 and SIGNATURE registers (described in Section 13.5). Only a power-on reset will leave the command mode. A more detailed description of the programming is given in the next sections. 13.2 Timing characteristics As described in the previous section, a start and stop condition is necessary for communication. The LOW-level duration before the rising edge of the start condition is defined as tstart. The HIGH-level duration after the rising edge of the stop condition is defined as tstop. These parameters, together with all other timing characteristics are shown in Table 13. tstart tstop 001aag817 Fig 13. OWI start and stop condition KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 17 of 36 NXP Semiconductors KMA199 Programmable angle sensor Figure 14 shows the coding of a single bit with a HIGH level of VIH and a LOW level of VIL. Here the pulse width t1 or t0 represents a logic 1 or a logic 0 of a full bit period Tbit, respectively. bit = 0 Tbit bit = 1 Tbit 0.175 tw0 0.375 tw1 0.625 0.825 0.25 0.75 001aag818 Fig 14. OWI timing 13.3 Sending and receiving data The master has to control the communication during sending or receiving data. The command byte defines the region, address and type of command requested by the master. In case of a read command, an additional handover or takeover bit must be inserted before and after the two data bytes (see Figure 12). However the OWI is a serial data transmission, whereas the Most Significant Byte (MSB) must be send at first. Table 14. 7 CMD7 Table 15. Bit 7 to 5 Format of a command byte 6 CMD6 5 CMD5 4 CMD4 3 CMD3 2 CMD2 1 CMD1 0 CMD0 Command byte bit description Symbol CMD[7:5] Description region bits 000 = 16-bit EEPROM 001 to 011 = reserved 100 = 16-bit register 101 to 111 = reserved 4 to 1 0 CMD[4:1] CMD0 address bits read/write 0 = write 1 = read A more detailed description of all customer accessible registers is given in Section 13.5. Both default value and the complete command including the address and write or read request are also listed. KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 18 of 36 NXP Semiconductors KMA199 Programmable angle sensor 13.3.1 Write access To write data to the EEPROM, the internal charge pump must be enabled by setting the bits EEP_CP_CLOCK_EN and EEP_WRITE_EN and waiting for tcp. The following procedure must be performed: • • • • Start condition: The master drives a rising edge after a LOW level Command: The master sends a write command (CMD0 = 0) Data: The master sends two data bytes Stop condition: The master drives a rising edge after a LOW level Figure 15 shows the write access of the digital interface. The signal OWI represents the data on the bus from the master or slave. The signals master output enable and slave output enable just symbolize if the master or the slave output is enabled or disabled, respectively. START master output enable OWI slave output enable CMD7 CMD0 WDATA15 WDATA0 STOP IDLE (2) (1) 001aag743 (1) Missing rising edges generate a time-out condition and the written data is ignored. (2) If the master does not drive the bus, the bus is defined by the bus-pull. Fig 15. OWI write access Note: As already mentioned in Section 13.1, the command mode has to be entered using the write procedure. If command mode is not entered, digital communication is not possible and the sensor operates in normal operating mode. After changing an address, the time tprog must elapse before changing another address. Finally the checksum must be recalculated and written, after changing the contents of the EEPROM (see Section 13.4). KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 19 of 36 NXP Semiconductors KMA199 Programmable angle sensor 13.3.2 Read access To read data from the sensor, the following procedure must be performed: • Start condition: The master drives a rising edge after a LOW level • Command: The master sends a read command (CMD0 = 1) • Handover: The master sends a handover bit, that is a logic 0 and disables the output after a three-quarter bit period • Takeover: The slave drives a LOW level after the falling edge for ttko(slv) • Data: The slave sends two data bytes • Handover: The slave sends a handover bit, that is a logic 0 and disables the output after a three-quarter bit period • Takeover: The master drives a LOW level after the falling edge for ttko(mas) • Stop condition: The master drives a rising edge after a LOW level Figure 16 shows the read access of the digital interface. The signal OWI represents the data on the bus from the master or slave. The signals master output enable and slave output enable just symbolize if the master or the slave output is enabled or disabled, respectively. START master output enable CMD7 CMD0 HANDSHAKE RDATA15 RDATA0 HANDSHAKE STOP IDLE (3) OWI (1) (5) slave output enable (2) (2) (4) 001aag744 (1) Duration of LOW level for slave takeover ttko(slv). (2) There is an overlap in the output enables of master and slave, because both drive a LOW level. However this ensures the independency from having a pull-up or pull-down on the bus. In addition it improves the ElectroMagnetic Compatibility (EMC) robustness, because all levels are actively driven. (3) Duration of LOW level for master takeover ttko(mas). (4) If the master does not take over and a pull-up exists, the stop condition is generated by the pull-up. Otherwise a time-out is generated if there is a pull-down and the slave waits for a rising edge as start condition. (5) If the master does not drive the bus, the bus is defined by the bus-pull. Fig 16. OWI read access KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 20 of 36 NXP Semiconductors KMA199 Programmable angle sensor 13.3.3 Entering the command mode After a power-on reset, the sensor provides a time slot tcmd(ent) for entering the command mode. A specific command sequence has to be send (see Figure 17). If command mode is not entered, the sensor starts in the normal operating mode. However the signature can be written by the master, if the sensor switches to diagnostic mode. During the command mode sequence, the analog output is enabled. The external programming hardware has to overdrive the output with the current Iod. If command mode is activated, the analog output is disabled and pin OUT/DATA operates as a digital interface. tcmd(ent) VDD OWI START 94h command 9Bh A4h STOP signature 001aag819 Fig 17. OWI command mode procedure 13.4 Cyclic redundancy check As already mentioned in Section 7, there is an 8-bit checksum for the EEPROM data. To calculate this value, the CRC needs to be generated with the MSB of the EEPROM data word at first over all corresponding addresses in increasing order. All addresses from 0h to Fh have to be read out for calculating the checksum. The Least Significant Byte (LSB) of address Fh which contains the previous checksum must be overwritten with 0h before the calculation can be started. Finally, the internal charge pump has to be enabled for programming by setting the bits EEP_CP_CLOCK_EN and EEP_WRITE_EN (see Table 16) and waiting for tcp. The generator polynomial for the calculation of the checksum is: G(x) = x + x + x + 1 With a start value of FFh and the data bits are XOR at the x8 point. 8 2 (9) KMA199_1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved. Product data sheet Rev. 01 — 26 April 2010 21 of 36 NXP Semiconductors KMA199 Programmable angle sensor 13.4.1 Software example in C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 #include // calc_crc accepts unsigned 16-bit data in data int c alc_crc( int c rc, u nsigned int d ata) { const int g poly = 0x107; // generator polynomial int i ; //index variable for ( i = 15; i >= 0; i--) { crc