6.5.5.3.1 Debugger Routing

The debugger explicitly selects the target AHB-AP in its request. AHB-AP0 is connected to the CPU’s (the Cortex M0+) AHB bus.

All debugger transactions addressed to a Private Peripheral Bus (PPB) peripheral remain within the CPU. The PPB is where the ARM embedded debug components reside. All debugger transactions are routed to the CPU’s main bus, where they can be forwarded to other peripherals of the system via the AHB bus matrix.