The figure below shows the active debugger lines with some components that will prevent the MPLAB PICkit 4 In-Circuit Debugger system from functioning.
Figure 1. Improper Circuit
Components
Specifically, these guidelines must be followed:
- Do not use pull-ups on PGC/PGD – they will disrupt the voltage levels, since these lines have programmable pull-down resistors in the debugger.
- 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.