We have a system that communicates with the engine controller via CAN communication on the STM32 F429ZI NUCLEO and has an APPS (Gas Pedal). When we supply this system via USB, the system works correctly, but when we supply the system with a 12V separate from the Vin leg, we cannot communicate with the motor driver. We can read the pedal with the LEDs on it, but it seems that there is a problem with CAN communication.
What is the schematic difference between USB supply and external supply? If there is a difference, what kind of system it can affect.
