How do I connect to the 8031 interrupt pins on the XS40 board?
Q:
I am interested in using the FPGA to create an external interrupt for the microcontroller (uC) on the XS40 board (v1.2). Unfortunately, neither pins used by the 8051 for external interrupts (port 3 bits 2 and 3) are directly connected to the FPGA. So, it appears that it is necessary to jumper a wire to one of the FPGA pins. But, which one? They appear to all be used up. Let me know which ones you have had success with or think would work best.
PS: I am also looking for a pin connected to the FPGA to use for 'reset'.
A:
You can use the FPGA pins that connect to the LED display to drive the interrupt and reset. Or use one of the FPGA pins attached to port 1 of the 8031 as long as you don't let the 8031 drive the attached port pin.