st10f272z2 STMicroelectronics, st10f272z2 Datasheet - Page 131

• Manufacturer Part Number: st10f272z2
• Description: 16-bit Mcu With 256 Kbyte Flash Memory And 20 Kbyte Ram
• Manufacturer: STMicroelectronics

ST10F272Z2
24.2
Concurrent transmission requests in DAR-mode (C-CAN
module)
Description
When the C-CAN module is configured to operate in DAR-mode (Disable Automatic
Retransmission) and the host requests the transmission of several messages at the same
time, only two of these messages are transmitted. For all other requested transmit
messages, the TxRqst bits are reset but no transmission starts, NewDat and IntPnd are kept
unchanged. For the two messages which are transmitted, the TxRqst and NewDat bits are
reset and IntPnd is set if it has been enabled by TxIE.
The normal operation mode (DAR = 0) is not affected by this phenomenon.
Workaround
The DAR-mode is intended to support time triggered operation (TTCAN level 1), accepting
the transmission of a message only in its dedicated time window. It is an error to request the
transmission of several messages at the same time. So no workaround is necessary for
TTCAN applications.
The progress of a requested transmission can be monitored by checking the message
object’s TxRqst and NewDat [optionally IntPnd] bits. In DAR-Mode, when a message
transmission has failed either because the transmission was disturbed or because it has not
started, it is necessary to request the message transmission again.
For details on DAR mode and message control registers, refer to user manual UM0409.
Known limitations
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