11.6.9 Error Capture Register
The CAN controller contains a dedicated Error Capture Register (ECR) that is used to perform additional CAN bus diagnostics. The ECR supports the following two different modes:
- Free-running mode: In Free-running mode, the ECR displays the field and bit position within the current CAN frame.
- Error-capture mode: In Error-capture mode, the ECR displays the bit position and type of the last captured CAN error.
In Error-capture mode, the ECR samples the field and bit position, when a CAN error is detected. In order to sample such an event, the ECR needs to be set by performing a write access to it. When the CAN is set to sample the event, the ECR only captures one error event. For successive error captures, the ECR needs to be set again. The following table provides the bits descriptions in the ECR register.
| Bit Number | Name | Reset Value | Description |
|---|---|---|---|
| [31:17] | Reserved | 0 | Reserved |
| [16:12] | Field | 0 | This specifies the field of the ECR 0x00: Stopped 0x01: Synchronize 0x05: Interframe 0x06: Bus idle 0x07: Start of frame 0x08: Arbitration 0x09: Control 0x0A: Data 0x0B: CRC 0x0C: ACK 0x0D: End of frame 0x10: Error flag 0x11: Error echo 0x12: Error delimiter 0x18: Overload flag 0x19: Overload echo 0x1A: Overload delimiter Others: N/A |
| [11:6] | Bit_number | 0 | Bit number inside of field |
| 5 | Rx_mode | 0 | When asserted, the CAN controller is the receiver. |
| 4 | Tx_mode | 0 | When asserted, the CAN controller is the transmitter. |
| [3:1] | Error_type | 0 | Specifies different error types 0: Arbitration loss 1: Bit error 2: Bit stuffing error 3: Acknowledge error 4: Form error 5: CRC error Others: N/A |
| 0 | Status | 0 | Status of the ECR register 0: The ECR register captured an error or is in free running mode. 1: The ECR register set to sample the event. |