STK1002/Troubleshooting
From AVRFreaks Wiki
NEXUS interface fails when PB[0..7] is connected to GPIO header on STK1000 by jumpersetting SW4
- GPIO[0..7] are multiplexed with NEXUS signals.
- Remove the jumper that connects PB[0..7] to GPIO lines.
DMARQ0 and DMARQ1 does not behave according to specification.
- These pins on AP7000 share functionality with Non Maskable Interrupt (NMI) and Interrupt A and they are therefore connected to debouncing capacitors on STK1000.
- USE DMARQ2 or DMARQ3 if possible. If DMARQ0 or DMARQ1 must be used then remove C65 and C66 on STK1000.