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M16C/5L Group, M16C/56 Group
23.1.9.1
NEWDATA Bit
The NEWDATA bit is set to 1 when a new message is being stored or has been stored to the mailbox.
The timing for setting this bit to 1 is simultaneous with the INVALDATA bit.
The NEWDATA bit is set to 0 by writing 0 by a program.
This bit cannot be set to 0 by writing 0 by a program while the related INVALDATA bit is 1.
23.1.9.2
SENTDATA Bit
The SENTDATA bit is set to 1 when data transmission from the corresponding mailbox is completed.
This bit is set to 0 by writing 0 by a program.
To set the SENTDATA bit to 0, first set the TRMREQ bit to 0.
Bits SENTDATA and TRMREQ cannot be set to 0 simultaneously.
To transmit a new message from the corresponding mailbox, set the SENTDATA bit to 0.
23.1.9.3
INVALDATA Bit
After the completion of a message reception, the INVALDATA bit is set to 1 while the received message
is being updated into the corresponding mailbox.
This bit is set to 0 immediately after the message has been stored. If the mailbox is read while this bit is
1, the data is undefined.
23.1.9.4
TRMACTIVE Bit
The TRMACTIVE bit is set to 1 when the corresponding mailbox of the CAN module begins transmitting
a message.
This bit is set to 0 when the CAN module has lost CAN bus arbitration, a CAN bus error occurs, or data
transmission is completed.
23.1.9.5
MSGLOST Bit
The MSGLOST bit is set to 1 when the mailbox is overwritten or overrun by a new received message
while the NEWDATA bit is 1. The MSGLOST bit is set to 1 at the end of the sixth bit of EOF.
This bit is set to 0 by writing 0 by a program.
In both overwrite and overrun modes, this bit cannot be set to 0 by writing 0 by a program during five
cycles of fCAN (CAN system clock) following the sixth bit of EOF.
23.1.9.6
TRMABT Bit
The TRMABT bit is set to 1 in the following cases:
• Following a transmission abort request, when the transmission abort is completed before starting
transmission.
• Following a transmission abort request, when the CAN module detects CAN bus arbitration lost or
a CAN bus error.
• In one-shot transmission mode (RECREQ bit = 0, TRMREQ bit = 1, and ONESHOT bit = 1), when
the CAN module detects CAN bus arbitration lost or a CAN bus error.
The TRMABT bit is not set to 1 when data transmission is completed. In this case, the SENTDATA bit is
set to 1.
The TRMABT bit is set to 0 by writing 0 by a program.
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
23. CAN Module
Page 567 of 803
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