7.3.4.5 Stopping Program Execution (Entering Debug Mode)

To enter Debug mode, the debugger issues the DebugReqOn JTAG instruction, which asserts the DebugReq input to the CPU core. Once the CPU enters Debug mode, the DebugAck signal is asserted, which can be determined by reading the Status. DebugAck or Result.DebugAckN register bits.