CAN Trcv TJA1051T/3 (Silent Mode): Can't see incoming messages on Rx buffers of MCU

[asishmishra]

Currently, I’m working on a CAN Transceiver (TJA1051T/3) interfaced with RH850 microcontroller. The Trcv  has only 2 operating modes i.e. Normal and Silent mode (no 'EN' pin present). In Normal mode both Rx & Tx work fine with my CAN register settings however, in the Silent mode I don’t see incoming message on the receive registers. In CAN Trcv silent mode, Tx doesn’t work but Rx should function normally (as mentioned in the Transceiver Datasheet). 

In order to enter ‘Silent mode’, I write ‘S’ pin to logical level High.

 Hence, we correctly enter the ‘Silent mode’, but we don’t see the incoming Can frames in the Rx buffers of the Microcontroller.

Is this behaviour expected with the Transceiver, or should I need to make necessary register changes in the Microcontroller to support Silent mode of the CAN Transceiver ???

[PetrS]

Hi,

if the RH850 is the only node who responds on the bus, then this could be caused by missing ACK. The MCU cannot ACK massage as TJA1051 transmitter is disabled in Silent mode and the MCU's CAN module should not store received message into internal RX buffer if message is not ACKed.

BR, Petr