I am looking into an issue where CAN drops off on power up. It looks like the microcontroller CAN mailbox fills up and it no longer transmits. I don’t think its necessarily a TJA1043 issue but I wanted to understand the inner workings of all the parts involved to resolve the issue.
Below I have the microcontroller connected to the TJA1043 transceiver and having a 49.9k resistor to ground on the TXD line CHASSIS1_CAN_TXD.
In the datasheet the TXD line has a current source pull up to VIO (see below screenshot of datasheet). Can you let me know how much current the pull up to VIO is? Or the resistance? Are you aware of any issues of having a external pull down resistor on the TXD line preventing microcontrollers from transmitting on the CAN bus?
