USAGE MANUAL: SIX AXIS TORQUE FORCE SENSOR BOARD (STRAIN)

Transcription

1 Page. 1 of 41 USAGE MANUAL: SIX AXIS TORQUE FORCE SENSOR BOARD (STRAIN) Rev. Prepared by 0.0 LC Date Approved Date 18/04/2008 Revision history Rev. Date Description /04/2008 Preliminary emission /08/2009 Updated for revision 001 of electronic board /08/2009 Document translated in English /12/2009 Corrected outgoing message payload at /06/2011 Updated to reorganized strain application and correct polling message

2 Page. 2 of 41 Summary Revision history...1 Summary...2 General description...3 Electtronics description...3 External connections...8 Test firmware description...9 Strain application...9 CAN Protocol messages...11 Initial test and configuration...38 Sensor calibration...39 References...41

3 Page. 3 of 41 General description Goal of this document is the specification of the HW and FW information needed for the use and HW/FW/SW development of the six axis torque and force sensor (STRAIN board). Electtronics description The board is based on a 16 bit DSP from Microchip (dspic30f4013), it samples up to a maximum of 6 analog channels for strain gauges sensors in a bridge configuration (using an instrumentation amplifier INA155); the Analog to digital converter (AD7685, 16 bit, 250 Ksps, SPI interface) is multiplexed (ADG658) on the 6 channels; for each channel is possible to dynamically modify the offset by means of a DAC (AD5310, 10bit, SPI interface), it is also possible to minimize the thermal drift effects of the strain gauges by placing proper compensation resistors on the free positions on the PCB. The values of these resistors are determined during the gluing and testing phase, each sensor (that has a unique serial number) is provided with a report stating the correct values. None of the sensor produced up to now has the compensation resistors mounted. The analog anti aliasing filters are a simple first order RC around 700Hz cutoff, so clearly is necessary to use oversampling techniques and digital filtering to receive the best signal with minimum noise; but must be considered that the digital filtering used now is around 80Hz the analog filtering could be lowered to Hz if a lower noise is needed. Sampling synchronization is managed by the DSPic, as well as digital data transmission on the CAN bus line (driver MAX3051); the DSP also provide the digital filtering (IIR low pass up to 10 order = 5 bi-quads) and coordinate transformation from strain gauges space to torque/force space (6x6 matrix multiplication). The sensors in the current application don t need a calibration and are provided with a unitary diagonal matrix. If needed there are CAN commands to change the values inside the matrix. The computing power of the microcontroller (clock 10Meg*8PLL, 20MIPS) is more than enough for sampling, digital filtering with a 0.125msec period, so each channel is sampled and filtered at 1,33Khz. Moreover the maximum CAN bus data transmission is set at 1KHz, same frequency of the coordinate transformation. Measurement based on these data shows that there is enough free elaboration time to add new features or increasing the sample rate if needed. All system configurations (sampling and communication rates, digital filtering, transformation matrix, FW update) are controlled by the CAN bus commands; with the CAN bus lines the board inside the sensor is powered (5VDC), to power the sensor using the bus lines on the robot is necessary to modify the BLL o MC4 control boards mounting the 0R0 resistor for the output of the 5V and changing the 100R resistor placed on the GND of the bus (for details see schematics and PCB of the BLL/MC4 boards). The board is fully protected against power supply inversions and over voltages but care must be taken in detecting the faulting conditions as soon as possible in order to avoid excess heat or damaging in the protection circuitry. Considered the difficulty of changing the CAN bus termination resistor inside the sensor (the sensor must be opened and then offset re-calibrated) is preferable to connect the sensor in the middle of the line as the sensors are provided by default un-terminated; if needed a single resistor of 120R can be soldered directly between CANL and CANH lines. The first programming of the DSP is done in testing phase using an ICD emulator and a reduced version of the system FW is loaded in order to completely test the sensor functionality, The FW version needed on the robot is updated directly when the sensors are installed by means of the CAN bootloader application as the testing version is slightly different.

4 1.1 Electrical schematics Page. 4 of 41

5 Page. 5 of 41

6 Page. 6 of 41

7 Page. 7 of PCB Layout 1.3 Internal connections diagram The electronic board is completely contained inside the mechanical part of the sensor, the only connection with the exterior is the CAN-power supply 4 lines cable (equipped with a Molex male connector). The strain gauges bridges are soldered directly on the lateral pads (18 contacts) as can be seen in the following images:

8 Page. 8 of 41 To determine how to connect the strain gauges is sufficient measure the terminal resistance with an ohmmeter: Between +V and GND a value around 800Ω is measured, from output signal and GND and from output and +V can be measured a value around 400Ω. The connection order of the internal channels is not mandatory (the calibration matrix can magically reconnect the wires by itself ;-) but all the sensors produced up to now are connected as can be seen in the upper photos. Pin Signal Color 1 +V1 blue 2 S2 red 3 GND2 yellow 4 +V2 gray 5 S1 black 6 GND1 White If needed is possible to connect the mechanical part to GND placing a small drop of solder on a SMT jumper near the central hole. The CAN bus and power supply are connected as follows: Pin Signal Color TP2 +5VDC Red TP15 GND Black TP6 CANL white TP3 CANH Green The current drawn from the power supply (+5VDC) is, in normal conditions, lower than 50mA so, if possible, supply the sensor using a stabilized power supply with current limit set at 100mA. Once the connections are done the board is placed inside the mechanical parts and fastened with a screw passing through the central hole. External connections The external connections are described as follows: Signal Color +5VDC Red GND Black CANL White CANH Green The connector type is Molex PicoBlade family, code

9 Page. 9 of 41 Test firmware description The test firmware is developed for testing the sensors in production phase, it uses a protocol very similar to the one used on the robot; the FW itself is very similar (the robot firmware has been developed starting from the test FW) but there are some differences that are out of the scope of this document to describe. The test firmware is developed completely in C (pic30-gcc V4.03) using MPLab IDE ver. 8.0 heavily using standard libraries provided by the development system both for peripheral management and DSP routines for matrix manipulation and digital filtering. The code is structured in a way that permits to use it for the test of STRAIN and MAIS boards (changing a #include). Strain application The strain application has the goal of read strain gauges sensors, calculates torque and force data and sends results on CAN bus. 1.4 How to calculate torque and force data The torque and force are calculated from the values read by the ADC on the six-axis. They are calculated in this way: The calibration tare is calculated during the calibration phase and saved in no-volatile memory, while current tare is in volatile memory ad it is initialized to 0.AGGIUNGERE QC ALTRO??? The correct mathematical formula is: Where: Fx, Fy, Fz are force value in Cartesian axis Tx,Ty,Tz are torque value in Cartesian axis Tmij, i and j vi, i (1,6) are element of Transformation Matrix (1,6) are values read by ADC on six-axis calibti, i currti, i (1,6) are the tare of axix i-th. (1,6) are the tare of axix i-th

10 Page. 10 of Numerical formats and data structure The application is configured with data contained in the global variable strain_config_data_t strain_cfg. Some of these data are saved in EEPROM memory and is reloaded each power on in order to provide the user for a nonvolatile configuration (useful for not so often changing values such the calibration matrix, CAN address, etc). Data saved in EEPROM are contained in ee_data field of strain_cfg variable. During running application, data are stored in strain_cfg variable in RAM; when it is necessary to save some data in EEPROM, then it is necessary to call function strain_config_saveinee(), that saves data contained in strain_cfg.ee_data in EEPROM. Both Strain and Mais applications must know their firmware and CAN protocol version in order to send these information to icubinterface. These data are stored in strain_srccode_info, a constant variable defined in strain_config.c. In main.c, it is possible to know version information by strain_srccode_info_ptr, a pointer to strain_srccode_info. Strain uses DSPIC30f-HAL-STRAIN library s services, for operate with CAN bus, timers, etc. Finally, it is important to note that all DSP calculation routines use for input and output data format the 1.15 fractional format. 1.6 Execution flow When Strain application starts, it initializes all peripherals and load configuration data from EEPROM. Then configures timer Timer1, with period defined in strain_cfg.ee_data.ee_an_channelscanningtime and sets priority of Timer1 IRQ with maximum value to avoid jittering in the data flow. Note that Timer1 IRQ consists in calling timer s callback function: s_timer1_callback() Then it enters in endless loop, during which verifies if there are messages in CAN received queue. This loop is interrupted only by Timer1 s IRQ and can s IRQ. The latter saves received messages in received queue. The elaboration process flux is mainly concentrated in interrupt service routine of Timer1. The Timer1 s IRQ reads strain gauges sensors and stores values in the strain_cfg.ee_data.ee_an_channelvalue variable; during this interrupt it also sets the DAC value of the next channel to be sampled in order to correct its offset; in this way, the analog signal has reached stable state at next IRQ time. Only at the end of 6-th Timer1 s IRQ, it calculates transformation matrix and transmits Torque/force data. It is important to note how reading is done: at each interrupt IRQ function reads the analogical channel identified by strain_cfg.ee_data.ee_an_selectedchannel and saves value in strain_cfg.ee_data.ee_an_channelvalue[strain_cfg.ee_data.ee_an_selectedchannel]. When all analogical channels are read, the IRQ calculates torque and force data and sends them on CAN bus. Since sending data on CAN bus can generate noise that disturbs analog channels readings, the IRQ waits two following interrupt before restarting to read the first channel. See following figure:

11 Page. 11 of 41 1th IRQ call Timer1 period Read AN channel num 0 Read AN channel num 1 Read AN channel num 2 Read AN Read AN channel channel num 3 num 4 Read AN channel num 5 Send data wait wait Read AN channel num Get Strain application source code Strain application is a free software released under Copyright (C) 2007 RobotCub Consortium, European Commission FP6 Project IST If you are interested in use Strain source code see [3]. CAN Protocol messages The application recognizes a series of CAN messages compatibles with the protocol used on the icub. According to ICub s CAN protocol, messages are divided in three classes: POLLING: for the board and system configuration PERIODIC: for the automated transmission of board s values at a predefined data rate. In case of Strain, board s values are of hall sensor data. CANLOADER: for upgrade board s firmware. This document describes CAN messages belonging to POLLING and PERIODIC classes supported by Strain application. See [1] for messages of CANLOADER class. Is important to note, that POLLING and PERIODIC messages of sensor boards (Strain, Mais, etc) have the same structure of POLLING and PERIODIC messages of motor control boards, but they are different in class id number: POLLING messages PERIODIC messages Sensor boards Class id number = 2 Class id number = 3 Motor control boards Class id number = 0 Class id number = 1 icub s CAN protocol uses can message with only Standard ID(11 bits). For more information about CAN message see [2]. A message, belonging to POLLING class, has the following structure:

12 Standard ID 3 bits 4bits 4bits Message Class Source Destination Page. 12 of 41 For brevity, in the following chapters, the messages will be represented this way: A message, belonging to PERIODIC class, has the following structure: Standard ID 3 bits 4bits 4bits Message Class Source Id Message For brevity, in the following chapters, the messages will be represented this way: CSI

13 Page. 13 of Polling messages The following sections describe the commands (polling messages) accepted by the Strain application. Strain application can be configured at compile time for response to each command(polling message), by setting Strain_cfg. can_ack_every_msg = 1. For convenience, in describing the message refers to that field with CAN_ACK_EVERY_MESSAGE.

14 Page. 14 of Get version #define CAN_CMD_GET_FW_VERSION 0x1C This command returns the type of board, numerical FW revision and CAN protocol version. 0x1C PROTOCOL. VERSION PROTOCOL. BUILD PROTOCOL.VERSION = icub Interface CAN protocol version PROTOCOL.BUILD = icub Interface CAN protocol build Response message syntax: 0x1C BOAR TYPE STRAIN EXE. VERSION EXE. REVISION EXE. BUILD PROTOCOL. VERSION PROTOCOL. BUILD COMPATIBILITY EXE.VERSION = version of executable file. (value defined at compile time) EXE.REVISION = revision of executable file. (value defined at compile time) EXE.BUILD = build of executable file. (value defined at compile time) PROTOCOL.VERSION = version of CAN protocol implemented. (value defined at compile time) PROTOCOL.BUILD = build of CAN protocol implemented. (value defined at compile time) COMPATIBILITY = 1 if icub Interface PROTOCOL.VERSION and PROTOCOL.BUILD is equal to strain CAN protocol implemented; = 0 otherwise.

15 Page. 15 of Set board CAN address #define CAN_CMD_SET_BOARD_ADX 0x32 Sets the board CAN address. 0x32 AA AA =board address, [1..15] If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: Errors: If the address is greater than 15 or equal to 0 an error of type ERR_CAN_PARAMETERS_INVALID is issued, but actually Strain application doesn t manage error really. Note: if application is configured to be saved always (strain_cfg.save_eeprom_atonce ==1), then the new address is saved in Eeprom.

16 Page. 16 of Set transmission mode #define CAN_CMD_SET_TXMODE 0x7 Activate and deactivate the continuous data transmission mode. 0x7 M M = transmission mode = 0 Transmit calibrated data continuously =1 Do acquisition but do not transmit =2 reserved. Actually not used. =3 Transmit NOT calibrated data continuously =4 Transmit calibrated and NOT calibrated data continuously. (Debug mode).in this mode Strain board sends 4 can message. If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: C = class periodic messages, 1

17 Page. 17 of Set CAN data rate #define CAN_CMD_SET_CANDATARATE 0x8 Sets the force and torque data transmission rate in milliseconds; maximum data rate 1msec, minimum data rate 210msec. 0x8 DR DR = data rate in msec. [1..210] If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM

18 Page. 18 of Save configuration to EE #define CAN_CMD_SAVE2EE 0x9 Save the current configuration data to EEPROM. 0x9 If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: Remarks: Use the Save To Eeprom command only if you are sure that: Other devices are NOT trying to send commands to the strain board during the save operation. Other devices are NOT expecting data from the strain board during the save operation. The strain board is NOT in the automatic transmission mode (see command Set Transmission Mode).

19 Page. 19 of Get Transformation Matrix Row Col value #define CAN_CMD_GET_MATRIX_RC 0xA Return the value of the element (R,C) of the Transformation Matrix. (This matrix is saved in eeprom). 0xA R C R:[0 5] row number x of matrix C:[0 5] column number y of matrix The response is : 0xA R C = class periodic messages, 1 C MSB LSB MSB and LSB of the element (R,C) of the Transformation Matrix.

20 Page. 20 of Set Transformation Matrix Row Col value #define CAN_CMD_SET_MATRIX_RC 0x3 Sets the value of the element (R,C) of the Transformation Matrix. (This matrix is saved in eeprom) 0x3 R C R:[0 5] row number of matrix C:[0 5] column number of matrix MSB and LSB of Transformation Matrix[R][C]. MSB LSB If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM

21 Page. 21 of Get DAC value #define CAN_CMD_GET_CH_DAC 0xB Gets offset of DAC converter for channel CH. 0xB CH CH:[0 5] number of DAC channel to read The response is: 0xB CH MSB MSB and LSB of channel CH value. LSB

22 Page. 22 of Set DAC value #define CAN_CMD_SET_CH_DAC 0x4 Sets the value of the DAC (10bits) for offset correction of the channel CH. 0x4 CH MSB C = class test messages, 2 CH:[0 5] number of DAC channel to change offset. MSB and LSB of channel CH. MLB If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding:

23 Page. 23 of 41 Get ADC value #define CAN_CMD_GET_CH_ADC 0xC Gets the current ADC measurement (16bit) for the channel CH. This value can be raw or calibrated 0xC CH M CH:[0 5] number of ADC channel to read. Mode: if M = 0 return raw CH value else return calibrated CH value The response is: 0xC CH MSB and LSB of channel CH. M MSB MLB

24 Page. 24 of 41 Get Matrix Gain #define CAN_CMD_GET_MATRIX_G 0x12 Gets Matrix Gain. This value is saved in eeprom during calibration phase. 0x12 Response message: 0x12 G C = class periodic messages, 1 G: value of matrix gain

25 Page. 25 of 41 Set Matrix Gain #define CAN_CMD_SET_MATRIX_G 0x11 Sets Matrix Gain. This value is saved in eeprom during calibration phase. 0x11 G G:value of matrix gain If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM

26 Page. 26 of 41 Get Full Scales #define CAN_CMD_GET_FULL_SCALES 0x18 Gets full scale of channel CH. This value is saved in eeprom during calibration phase. 0x18 CH CH:[0 5] number of channel Response message: 0x18 CH MSB CH:[0 5] number of channel MSB and LSB of the channel s full scale LSB

27 Page. 27 of 41 Set Full scales #define CAN_CMD_SET_FULL_SCALES 0x17 Sets full scale of channel CH. This value is saved in eeprom during calibration phase. 0x17 CH MSB CH:[0 5] number of channel MSB and LSB of the channel s full scale LSB If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM

28 Page. 28 of 41 Set serial number #define CAN_CMD_SET_FULL_SCALES 0x19 Sets board s serial number. Serial number is saved in eeprom. 0x19 a b A,b,c,d,e,f,g are characters of serial number. c d e f If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM. g

29 Page. 29 of 41 Get serial number #define CAN_CMD_GET_SERIAL_NO 0x1A Gets board s serial number. Serial number is saved in eeprom. 0x1A Response message is: 0x1A a A,b,c,d,e,f,g are characters of serial number. b c d e f g NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM.

30 Page. 30 of 41 Get Eeprom Status #define CAN_CMD_GET_EEPROM_STATUS 0x1B Return 0 if board received one of this commands: CAN_CMD_SET_CALIB_TARE CAN_CMD_SET_MATRIX_RC CAN_CMD_SET_CH_DAC CAN_CMD_SET_MATRIX_G CAN_CMD_SET_SERIAL_NO and it has not received Save to EEPROM command yet. Return 1otherwise. This command is used by CanLoader Calibrate Window only. 0x1B

31 Page. 31 of 41 Get Calibration Tare #define CAN_CMD_GET_CALIB_TARE 0x14 Gets calibration tare of channel CH. (Set during calibration phase). It is saved in Eeprom. 0x14 CH CH:[0 5] number of channel Response message: 0x 14 CH MSB CH:[0 5] number of channel MSB and LSB of the channel s calibration tare. LSB

32 Page. 32 of 41 Set Calibration Tare #define CAN_CMD_SET_CALIB_TARE 0x13 Sets calibration tare of channel CH or of all channels. (Set during calibration phase). It is saved in Eeprom. 0x13 V CH MSB LSB V: If = 0, set 0 calibration tare for all channels If = 1, set calibration tare to negative number of actual ADC channel value (for all channels) If = 2, set calibration tare for channel CH with MSB and LSB value. If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding: NOTE: The set value can be saved to EEPROM in order to be recalled each time the sensor is powered or reset, for details see the command Save to EEPROM.

33 Page. 33 of 41 Get Current Tare #define CAN_CMD_GET_CURR_TARE 0x16 Gets current tare of channel CH. Its value are temporary, not saved in eeprom. If not used it is initialized with 0. 0x16 CH CH:[0 5] number of channel Response message: 0x 16 CH MSB CH:[0 5] number of channel MSB and LSB of the channel s current tare. LSB

34 Page. 34 of 41 Set Current Tare #define CAN_CMD_SET_CURR_TARE 0x15 Sets current tare of channel CH or of all channels. 0x15 V CH MSB LSB V: If = 0, sets current tare for all channels equal to 0 If = 1, sets current tare to the negative number of current Torque value, that is sets the current tare to current value. (for all channels). If = 2, set current tare for channel CH with MSB and LSB value. If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding:

35 Page. 35 of 41 Set Multiplexer Channel number #define CAN_CMD_MUX_NUM 0xF Sets number of channels to multiplex. Deprecated. It can be used only for test porpoise. 0xF CH CH: number of channels If CAN_ACK_EVERY_MESSAGE is defined, return the command code as acknowledge following the coding:

36 Page. 36 of Outgoing messages When the automatic transmission is enabled (see Set Transmission Mode command), the two following messages are periodically transmitted. (default transmission period: 1ms) #define CAN_CMD_FORCE_VECTOR #define CAN_CMD_TORQUE_VECTOR 0xA 0xB CSI LSBFT1 MSBFT1 LSBFT2 MSBFT2 LSBFT3 MSBFT3 C = class PERIODIC message 3 I = Force vector/torque vector [A or B] MSB, LSB = MSB and LSB of force/torque value

37 By default the sensors are programmed to use the address 0xF. In the following image can be seen some outgoing messages. Page. 37 of 41

38 Page. 38 of 41 Initial test and configuration After closing completely the sensor, for some application is necessary to evaluate the offset correction values of each channel and find a suitable correction value, this task can be accomplished using a CAN graphing application such as ESD CANPlot or Gulp, plotting outgoing data for each channel, the offset can be corrected using the command Set DAC Value for channel x in order to obtain 6 overlapping lines on the graph. Once a set of values has been determined the configuration can be written in EEPROM using the command Save to EEPROM in order to reload the correction values at every power on or reset.

39 Page. 39 of 41 Sensor calibration The calibration of the sensor can be performed using the appropriate CAN commands (described the previous sections) or using the calibration utility included in the CANLOADER application Offset correction (calibration of the DAC unit) To change the offsets correction values of DAC unit, use the commands Set DAC Value for channel x and Get DAC Value for channel x described in the previous sections. You can monitor the output of the sensor using a graphical application such as ESD CANPlot or Gulp and change the DAC correction offsets in order to obtain 6 overlapping lines on the graph. You can also adjust the correction values using the calibration utility included in the CANLOADER application. When the canloader is connected, select the desired strain board from the list of detected devices and press the CALIBRATE button. The window that will appear will display the current readings of the six channels of the sensor and the values of the six DAC converters used to calibrate the offsets of the channels. The unit can be then calibrated manually, by moving the sliders until all the six channels will display a reading close to Do not apply any force of torque to the sensor during the calibration. Optionally, the auto-calibrate button will try to find automatically the correct offsets. When the calibration process is complete, the six offset can be saved to the eeprom using the save to eeprom button. Calibration window using the CANLOADER application. Using a graphical application (CANplot in this example), change the DAC offset in order to obtain 6 overlapping lines.

40 Page. 40 of Calibration of the transformation matrix The transformation matrix allows to convert the data sampled from the strain gauges to the effective force and torque values. This transformation is done by multiplying the vector of raw strain gauges data ε = [ε1, ε2, ε3, ε4, ε5, ε6]t by a transformation matrix K ϵ R6X6: f = Kε the result is a vector f = [Fx, Fy, Fz, τx, τy, τz] t containing the force and torque values. The calculation of the coefficients of the matrix K (sensor calibration) needed for this operation is outside the scope of this document. The matrix coefficients are represented with the 1.15 fractional format: e.g corresponds to the HEX value of 0x7FFF, 0.5 to 0x4000, 0.25 to 0x2000, 0.0 to 0x0000, to 0xE000, -0.5 to 0xC000 and -1.0 to 0x8000 (See for examples). The transformation matrix is by default initially set equal to the identity matrix, i.e: To change the coefficients of the transformation matrix, use the CAN commands SET MATRIX and GET MATRIX described in the previous sections. Additionally, the coefficients of the transformation matrix can be changed using the canloader utility. When the canloader is connected, select the desired strain board from the list of detected devices and press the CALIBRATE button. The bottom right part of the window will display the transformation matrix. When the calibration process is complete, the transformation matrix can be saved to the eeprom using the save to eeprom button.

41 Page. 41 of 41 References [1] [2] [3] CanLoader protocol specification: DIST_100_D_15_01_CANLOADER_PROTOCOL.doc CAN bus specification: Strain_develop_howto_001.odt in pic30f4013/strain