Espressif ESP32 Technical Reference Manual page 560

21 Two-wire Automotive Interface (TWAI)
• If
TWAI_ERR_ST = 0 and
old value set by TWAI_ERR_WARNING_LIMIT_REG
21.5.3.4 Data Overrun Interrupt (DOI)
The Data Overrun Interrupt (DOI) is triggered when the message being read is overrun and invalid.
The DOI is only triggered on the first message that causes the Receive FIFO to overrun (i.e., the transition from
the Receive FIFO not being full to the Receive FIFO overrunning). Any subsequent overrun messages will not
trigger the DOI again. The DOI will only be able to trigger again when all received messages (valid or overrun)
have been cleared.
21.5.3.5 Error Passive Interrupt (TXI)
The Error Passive Interrupt (EPI) is triggered whenever the TWAI controller transitions from Error Active to Error
Passive, or vice versa.
21.5.3.6 Arbitration Lost Interrupt (ALI)
The Arbitration Lost Interrupt (ALI) is triggered whenever the TWAI controller is attempting to transmit a message
and loses arbitration. The bit position where the TWAI controller lost arbitration is automatically recorded in
Arbitration Lost Capture register
Capture register will no longer record new bit location until it is cleared (via a read from the CPU).
21.5.3.7 Bus Error Interrupt (BEI)
The Bus Error Interrupt (BEI) is triggered whenever TWAI controller observes an error on the TWAI bus. When
a bus error occurs, the Bus Error type and its bit position are automatically recorded in the Error Code Capture
register (TWAI_ERR_CODE_CAP_REG). When the BEI occurs again, the Error Code Capture register will no longer
record new error information until it is cleared (via a read from the CPU).
21.5.4 Transmit and Receive Buffers
21.5.4.1 Overview of Buffers
Table 21-8. Buffer Layout for Standard Frame Format and Extended Frame Format
Standard Frame Format (SFF)
TWAI address
0x40
0x44
0x48
0x4c
0x50
0x54
0x58
0x5c
0x60
Espressif Systems
TWAI_BUS_OFF_ST = 1: The TWAI controller's TEC has dropped below the thresh-
(TWAI_ARB LOST CAP_REG). When the ALI occurs again, the Arbitration Lost
Content
TX/RX frame information
TX/RX identifier 1
TX/RX identifier 2
TX/RX data byte 1
TX/RX data byte 2
TX/RX data byte 3
TX/RX data byte 4
TX/RX data byte 5
TX/RX data byte 6
Submit Documentation Feedback
during BUS_OFF recovery.
Extended Frame Format (EFF)
TWAI address Content
0x40 TX/RX frame information
0x44 TX/RX identifier 1
0x48 TX/RX identifier 2
0x4c TX/RX identifier 3
0x50 TX/RX identifier 4
0x54 TX/RX data byte 1
0x58 TX/RX data byte 2
0x5c TX/RX data byte 3
0x60 TX/RX data byte 4
560 ESP32 TRM (Version 5.2)