1. When I use the JTAG debugger to program the microcontroller, I can NOT provide a reset from the SBC to the microcontroller because the JTAG debugger holds the reset line. Is this understanding correct?? For now I am using the serial programming (SCI) using RappID bootloader. The question is more a clarification.
2. I can program the microcontroller through the SCI when I use the standalone DC power supply of 12V but I cannot program the microcontroller through the SCI when I use the power supply from the SBC (3.3V). I notice the SCI line voltages are the SAME when I use the two different power supplies. Why can I not program through the SCI while using the power supply (3.3V) from the SBC as indicated in the image below?