TCAN330: About TXD and RXD waveforms

Hello,

Yes, the waveforms of a CAN transceiver are generated by toggling TXD low and high, that waveform is then translated to a differential signal on the CANH and CANL lines. The receiver portion of the CAN transceiver then reads the CANH and CANL waveforms and translates back to a logic signal on RXD to be read by the controller.

Regards,

Eric Hackett 

By from the load I think you mean from CANH and CANL.

The differential signal on CANH and CANL is translated to the logic signal on RXD by measuring the differential voltage between CANH and CANL. So, if RXD is low, that means there is a differential voltage greater than 900mV between CANH and CANL. If the signal on RXD is high, the differential between CANH and CANL is less than 500mV.

Regards,

Eric Hackett 

Yes, these are both correct. And yes, the controller manages if it is receiving or transmitting information at any given time. The controller needs to be constantly reading RXD to process message priority, as well as verify any errors during communication.

Regards,

Eric Hackett 

In the CAN frame, there is an ID section, the more 0s (the more dominant bits from MSB to LSB) the high the priority because the message ID dominates the CAN bus. The controller can then determine if the ID it is transmitting matches the ID the bus is reflecting by reading its own RXD pin.

Regards,

Eric Hackett