eCAN Registers
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SPRUI07–March 2020
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Controller Area Network (CAN)
13.8.4 Transmission-Request-Reset Register (CANTRR)
These bits can only be set by the CPU and reset by the internal logic. These bits are reset when a
transmission is successful or is aborted. If the CPU tries to set a bit while the CAN tries to clear it, the bit
is set.
Setting the TRR[n] bit of the message object n cancels a transmission request if it was initiated by the
corresponding bit (TRS[n]) and is not currently being processed. If the corresponding message is currently
being processed, the bit is reset when a transmission is successful (normal operation) or when an aborted
transmission due to a lost arbitration or an error condition is detected on the CAN bus line. When a
transmission is aborted, the corresponding status bit (AA.31-0) is set. When a transmission is successful,
the status bit (TA.31-0) is set. The status of the transmission request reset can be read from the TRS.31-0
bit.
The bits in CANTRR are set by writing a 1 from the CPU.
Figure 13-13. Transmission-Request-Reset Register (CANTRR)
31 0
TRR[31:0]
RS-0
LEGEND: RS = Read/Set; -n = value after reset
Table 13-12. Transmission-Request-Reset Register (CANTRR) Field Descriptions
Bit Field Value Description
31:0 TRR[31:0] Transmit-request-reset bits
1 Setting TRRn cancels a transmission request
0 No operation
13.8.5 Transmission-Acknowledge Register (CANTA)
If the message of mailbox n was sent successfully, the bit TA[n] is set. This also sets the GMIF0/GMIF1
(CANGIF0.15/CANGIF1.15) bit if the corresponding interrupt mask bit in the CANMIM register is set. The
GMIF0/GMIF1 bit initiates an interrupt.
The CPU resets the bits in CANTA by writing a 1. This also clears the interrupt if an interrupt has been
generated. Writing a 0 has no effect. If the CPU tries to reset the bit while the CAN tries to set it, the bit is
set. After power-up, all bits are cleared.
Figure 13-14. Transmission-Acknowledge Register (CANTA)
31 0
TA[31:0]
RC-0
LEGEND: RC = Read/Clear; -n = value after reset
Table 13-13. Transmission-Acknowledge Register (CANTA) Field Descriptions
Bit Field Value Description
31:0 TA[31:0] Transmit-acknowledge bits
1 If the message of mailbox n is sent successfully, the bit n of this register is set.
0 The message is not sent.
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