SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
In Restricted Operation Mode the CAN node is able to receive data and remote frames and to give acknowledge to valid frames, but it does not send data frames, remote frames, active error frames, or overload frames. In case of an error condition or overload condition, it does not send dominant bits, instead it waits for the occurrence of bus idle condition to resynchronize itself to the CAN communication. The recieve and transmit error counters (MCAN_ECR[14:8] REC and MCAN_ECR[7:0] TEC) are frozen while CAN error logging (MCAN_ECR[23:16] CEL) is active. The Host CPU can set the MCAN module into Restricted Operation Mode by setting MCAN_CCCR[2] ASM bit. The bit can only be set by the Host CPU at any time when both MCAN_CCCR[2] CCE and MCAN_CCCR[1] INIT bits are set to 1.
The Restricted Operation Mode is automatically entered when the Tx Handler was not able to read data from the Message RAM in time. To leave Restricted Operation Mode, the Host CPU has to reset MCAN_CCCR[2] ASM bit. This mode can be used in applications that adapt themselves to different CAN bit rates. In this case the application tests different bit rates and leaves the Restricted Operation Mode after it has received a valid frame.
The Restricted Operation Mode must not be combined with the Loop Back Mode.