Espressif ESP32 Technical Reference Manual page 565

21 Two-wire Automotive Interface (TWAI)
– The first 16 bits of the 29-bit ID
The following Figure 21-9 illustrates how the 32-bit code and mask values will be interpreted under Dual Filter
Mode.
Figure 21-9. Dual Filter Mode
21.5.7 Error Management
The TWAI protocol requires that each TWAI node maintains the Transmit Error Count (TEC) and Receive Error
Count (REC). The value of both error counts determine the current error state of the TWAI controller (i.e., Error Ac-
tive, Error Passive, Bus-Off). The TWAI controller stores the TEC and REC values in the TWAI_TX_ERR_CNT_REG
and TWAI_RX_ERR_CNT_REG respectively, and can be read by the CPU at anytime. In addition to the error
states, the TWAI controller also offers an Error Warning Limit (EWL) feature that can warn the user regarding the
occurrence of severe bus errors before the TWAI controller enters the Error Passive state.
Espressif Systems 565 ESP32 TRM (Version 5.2)
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