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projects:pic32mx_obd_evaluation_board [2017/01/03 11:39] admin [Getting temperature from MCP9801 temperature sensor] |
projects:pic32mx_obd_evaluation_board [2019/08/20 18:33] (current) admin [PIC32MX OBD Evaluation Board] |
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| ====== PIC32MX OBD Evaluation Board ====== | ====== PIC32MX OBD Evaluation Board ====== | ||
| - | {{:projects:dsc_5593_800x536.jpg?512 |}} | + | {{:projects:dsc_5593_800x536.jpg?456 |}} |
| ===== Requirements ===== | ===== Requirements ===== | ||
| ===== Basics of communication protocol ===== | ===== Basics of communication protocol ===== | ||
| Line 73: | Line 73: | ||
| ^ R | RFID module | | ^ R | RFID module | | ||
| ^ Q | data acquisition module | | ^ Q | data acquisition module | | ||
| - | |||
| ==== Generic NAK responses (shared by all modules) ==== | ==== Generic NAK responses (shared by all modules) ==== | ||
| Line 93: | Line 92: | ||
| * low level communication with devices on I²C bus | * low level communication with devices on I²C bus | ||
| ==== Commands ==== | ==== Commands ==== | ||
| + | ^ c | calculate CRC checksum for given data | | ||
| ^ C | configure communication parameters | | ^ C | configure communication parameters | | ||
| ^ d | get date and time | | ^ d | get date and time | | ||
| Line 101: | Line 101: | ||
| ^ i | read data from I²C device | | ^ i | read data from I²C device | | ||
| ^ I | write data to I²C device | | ^ I | write data to I²C device | | ||
| + | ==== Calculating CRC checksum ==== | ||
| + | <code> | ||
| + | Query | ||
| + | ---------------------------------------------- | ||
| + | | SOF | P | c | TYPE | P1..P4 | D1..DN | EOF | | ||
| + | ---------------------------------------------- | ||
| + | </code> | ||
| + | where | ||
| + | ^ TYPE | 1b | s - 16-bit CRC-CCITT calculated by software (only P4 used); d - CRC calculated by DMA module | | ||
| + | ^ P1 | 1b | 0 - input data not reflected (MSB first); ≠0 - input data reflected (LSB first) | | ||
| + | ^ P2 | 1b | length of CRC polynom (1..32) | | ||
| + | ^ P3 | 4b | CRC polynom | | ||
| + | ^ P4 | 4b | CRC seed | | ||
| + | ^ D1..DN | Nb | data in form of ASCII HEX | | ||
| + | <code> | ||
| + | Response | ||
| + | ------------------------------------------- | ||
| + | | SOF | P | 00 | CRC | TIME | CHSUM | EOF | | ||
| + | ------------------------------------------- | ||
| + | </code> | ||
| + | where | ||
| + | ^ CRC | 4b | calculated CRC | | ||
| + | ^ TIME | 2b | time in μs the calculation process took | | ||
| + | Error codes | ||
| + | ^ N02 | Invalid parameters provided | | ||
| ==== Configuring communication parameters ==== | ==== Configuring communication parameters ==== | ||
| <code> | <code> | ||
| Line 253: | Line 278: | ||
| Error codes | Error codes | ||
| ^ ?? | ?? | | ^ ?? | ?? | | ||
| - | |||
| ===== Carmon logger ===== | ===== Carmon logger ===== | ||
| Carmon logger module provides API for | Carmon logger module provides API for | ||
| * configuring operating mode of Carmon logger device | * configuring operating mode of Carmon logger device | ||
| + | * determining last sector written by Carmon logger | ||
| + | * reading sectors from the log device | ||
| ==== Commands ==== | ==== Commands ==== | ||
| ^ C | configure the module | | ^ C | configure the module | | ||
| + | ^ l | get number of last sector written by Carmon logger | | ||
| + | ^ R | read blocks from the log device according to provided parameters | | ||
| + | ^ r | read subsequent blocks from the log device according to parameters previously set via 'R' command| | ||
| ==== Configure the module ==== | ==== Configure the module ==== | ||
| <code> | <code> | ||
| Line 274: | Line 303: | ||
| | SOF | L | A | CHSUM | EOF | | | SOF | L | A | CHSUM | EOF | | ||
| ----------------------------- | ----------------------------- | ||
| + | </code> | ||
| + | ==== Read sectors from the log device according to provided parameters ==== | ||
| + | <code> | ||
| + | Query | ||
| + | -------------------------------------------------------- | ||
| + | | SOF | L | R | CONF | SECSTART | BLKNUM | CHSUM | EOF | | ||
| + | -------------------------------------------------------- | ||
| </code> | </code> | ||
| + | where | ||
| + | ^ CONF | 1b | configures how sectors are transfered to the master | | ||
| + | ^ SECSTART | 4b | number of 1st sector to be read | | ||
| + | ^ BLKNUM | 4b | number of blocks to be read | | ||
| + | Format of CONF word: | ||
| + | ^ bit# ^7^6^5^4^3^2..0^ | ||
| + | ^ | NA | NA | NA | 1/0..binary/ASCII mode | 1/0..block is/is not compressed | number of sectors in block (1-8) | | ||
| + | <code> | ||
| + | ACK response - standard ASCII mode | ||
| + | ----------------------------------------------- | ||
| + | | SOF | L | A | SN | B1D1..B1DN | CHSUM | EOF | | ||
| + | ----------------------------------------------- | ||
| + | ----------------------------------------------- | ||
| + | | SOF | L | A | SN | B2D1..B2DN | CHSUM | EOF | | ||
| + | ----------------------------------------------- | ||
| + | ... | ||
| + | ----------------------------------------------- | ||
| + | | SOF | L | A | SN | BMD1..BMDN | CHSUM | EOF | | ||
| + | ----------------------------------------------- | ||
| + | ACK response - binary mode | ||
| + | --------------------------------------------------- | ||
| + | | DLE | STX | SN | B1D1..B1DN | CHSUM | DLE | ETX | | ||
| + | --------------------------------------------------- | ||
| + | --------------------------------------------------- | ||
| + | | DLE | STX | SN | B2D1..B2DN | CHSUM | DLE | ETX | | ||
| + | --------------------------------------------------- | ||
| + | ... | ||
| + | --------------------------------------------------- | ||
| + | | DLE | STX | SN | BMD1..BMDN | CHSUM | DLE | ETX | | ||
| + | --------------------------------------------------- | ||
| + | </code> | ||
| + | where | ||
| + | ^ SN | 1b | sequence number (01-FF); incremented with each packet; useful for detection of packet loss | | ||
| + | ^ BxD1..BxDN | Nb | Xth data block (CONF[2..0] sectors) | | ||
| + | note: When operating in binary mode, each DLE data byte is replaced with sequence of two DLE bytes. | ||
| ===== RFID module ===== | ===== RFID module ===== | ||
| RFID module provides API for | RFID module provides API for | ||
