The figure below shows the active debugger lines with some components that will prevent
the MPLAB ICE 4 In-Circuit
Emulator from functioning.
Figure 1. Improper Circuit
Components
In particular, these guidelines must be followed:
- Do not use pull-ups on PGC/PGD – they could disrupt the voltage levels.
- Do not use capacitors on PGC/PGD – they will prevent fast transitions on data
and clock lines during programming and debugging communications, and slow
programming times.
- Do not use capacitors on MCLR – they will prevent fast transitions of VPP. A
simple pull-up resistor is generally sufficient.
- Do not use diodes on PGC/PGD – they will prevent bidirectional communication
between the debugger and the target device.