3.4 CPU Reset Extension

All the devices with a DSU have the CPU reset extension feature that allows a connection to a debugger while the CPU is under reset. This is also known as cold-plugging or also core-hold reset. For more details, see the PIC32CX-BZ2 and WBZ45 Family Data Sheet (DS70005504).

This feature requires the debug tool to control the level of SWCLK and MCLR pins.

This feature mainly avoids the execution of potentially corrupted code at boot and allows a connection to a device safely without any assumption on its current state. The debugger can read or write memory and peripherals without any delay from the CPU.

Note: After the initial connect sequence, the debugger must release the CPU reset extension to write to memory located outside the CPU (in other words, RAM, NVM and Peripherals) using Port 0 of the two Memory Access Port (MEM-AP). For more details, see Access Port(s). The debugger can use the reset vector catch feature to prevent the CPU from executing the user’s code.