Mixing CAN nodes with and without transceivers on one bus?
This could work:







simulate this circuit &ndash; Schematic created using CircuitLab

If MCU1 wants to transmit is will pull the line shared with MCU2 and transceiver's CANTX line via D2 and D4.

If MCU2 wants to transmit it will pull the line shared with MCU1 and transceiver's CANTX line via D1 and D5.

If the transceiver receives a zero it will pull the shared line via D3.

When none of the devices is driving then lines are pulled high by resistors.

It is "hackish". I would consider different interfaces (like SPI or I2C, or a bunch of UARTs) for communicating on the same PCB and making one MCU a gateway to external CAN bus.