Good morning to everyone:
I have a prototype made on the basis of the evaluation board of micro ADUC845/6/7 in which I have added a driver 485 and an operational amplier in the DAC output. Below is the drawing.
The problem I find that putting the PSEN pin low level (GND) and do the reset, the bootloader does not start. I'm using the original TTL to 232 cable of the evaluation board to communicate with the PC (I take the power for this cable from AVDD and GND.
I have the same configuration (I think) mounted on the evaluation board and everything works fine.
What could be wrong? I would appreciate your help.