µVision4 User's Guide

TPIU Initialization after RESET (Cortex-M)

This hint applies to Cortex-M devices enabled for capturing trace when debugging on hardware. After a software RESET, the CPU is put into the default debug mode. While the personal debug settings are restored automatically, the Trace Port Interface Unit (TPIU) remains disabled. As a consequence, trace is no longer captured. To overcome this pitfall, use the special debug function OnResetExec() in the initialization file for enabling the TPIU without restarting a debug session.

Generalized example for an initialization file:

FUNC void EnableTPIU (void)  {         // function with initialization statements
   // code to initialize TPIU
}

EnableTPIU();                          // executes whenever a debug session is started.

FUNC void OnResetExec (void)  {        // executes upon software RESET; Use the function name as is
   EnableTPIU();                       // call the initialization function
}

Initialization examples for devices that enable the 4-PIN Trace (ETM) TPIU are located in Configure Cortex-M Devices for Tracing of the ULINKpro User's Guide.