50.7.4.3 Overload

The overload frame is provided to request a delay of the next data or remote frame by the receiver node (“Request overload frame”) or to signal certain error conditions (“Reactive overload frame”) related to the intermission field respectively.

Reactive overload frames are transmitted after detection of the following error conditions:

• Detection of a dominant bit during the first two bits of the intermission field
• Detection of a dominant bit in the last bit of EOF by a receiver, or detection of a dominant bit by a receiver or a transmitter at the last bit of an error or overload frame delimiter

The CAN controller can generate a request overload frame automatically after each message sent to one of the CAN controller mailboxes. This feature is enabled by setting the CAN_MR.OVL bit.

Reactive overload frames are automatically handled by the CAN controller even if OVL is not set. An overload flag is generated in the same way as an error flag, but error counters do not increment.