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| projects:pic32mx_obd_evaluation_board [2017/01/25 17:47] – [Calculating CRC checksum] admin | projects:pic32mx_obd_evaluation_board [2026/10/25 19:30] (current) – external edit 127.0.0.1 | ||
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| ====== PIC32MX OBD Evaluation Board ====== | ====== PIC32MX OBD Evaluation Board ====== | ||
| - | {{: | + | {{: |
| ===== Requirements ===== | ===== Requirements ===== | ||
| ===== Basics of communication protocol ===== | ===== Basics of communication protocol ===== | ||
| Line 109: | Line 109: | ||
| </ | </ | ||
| where | where | ||
| - | ^ TYPE | 1b | s - CRC-CCITT calculated by software (Px ignored); h - CRC calculated by DMA module | | + | ^ TYPE | 1b | s - 16-bit |
| ^ P1 | 1b | 0 - input data not reflected (MSB first); ≠0 - input data reflected (LSB first) | | ^ P1 | 1b | 0 - input data not reflected (MSB first); ≠0 - input data reflected (LSB first) | | ||
| - | ^ P2 | 1b | length of CRC polynom (max 32) | | + | ^ P2 | 1b | length of CRC polynom (1..32) | |
| ^ P3 | 4b | CRC polynom | | ^ P3 | 4b | CRC polynom | | ||
| ^ P4 | 4b | CRC seed | | ^ P4 | 4b | CRC seed | | ||
| Line 125: | Line 125: | ||
| ^ TIME | 2b | time in μs the calculation process took | | ^ TIME | 2b | time in μs the calculation process took | | ||
| Error codes | Error codes | ||
| - | ^ EINVAL | + | ^ N02 | Invalid parameters provided | |
| ==== Configuring communication parameters ==== | ==== Configuring communication parameters ==== | ||
| < | < | ||
