st10f272z2 STMicroelectronics, st10f272z2 Datasheet - Page 132

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

Known limitations
24.3
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Transmission request disabled (C-CAN module)
Description
The transmission request of a message object may remain disabled (even if the host
immediately enables it again) in the following situations:
1.
2.
Reading the transmission request bit of this message object does not show that the
transmission request is disabled. This only happens when this message object is the only
one with a pending transmission request.
If the transmission request is blocked in the disabled state, it will be re-enabled by the first
activity detected on the CAN bus or by setting the transmission request of any other
message object.
The other message objects are not affected by this phenomenon.
Workaround
It is usually not necessary to disable the transmission request of a message object. If the
message object is to be used for another message, it is sufficient to prepare the new content
for this message object in the CPU interface register (Identifier, DLC, Data, with TxRqst and
NewDat [optionally TxIE] bits) and to transfer this content into the message object. The new
content is transmitted at the next opportunity. It is not altered by a possibly ongoing
transmission of the previous content of the same message object.
if the host disables the pending transmission request of the lowest-priority message
object (number 32 by default) in the short time window during which the message
handler state machine prepares the transmission of the message
if the transmission has not started.
ST10F272Z2