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Enable Serial Wire Trace

To enable Serial Wire Trace on STMicroelectronics STM32F10xxx devices:

  • Use a ULINK2 connector interface that supports Serial Wire, and connect ULINK2 to the board and to the host computer.
  • Enable the Trace Port Interface as described in the STM32F103xx Reference Manual, chapters Pinout and Debug Port Pins and TRACE Pin Assignment.
  • Configure µVision to capture trace data.

Enable the Trace Port Interface

  1. Create a text file, for example conf_STM32F10_SWO.ini, and enter the following code:
    ** Define the function to enable the trace port
    FUNC void EnableTPIU(void) {
      _WDWORD(0xE0042004, 0x00000020);    // Set asynchronuous communication via DBGMCU_CR
    ** Invoke the function at debugger startup

    Use the _WDWORD command to configure the TRACE_IOEN and TRACE_MODE bits of the DBGMCU_CR register: _WDWORD(0xE0042004, 0x00000020);

  2. Open the dialog Options for Target — Debug and insert conf_STM32F10xxx.ini into the Initialization File field.

    Configure the device for tracing

Configure µVision to capture trace data

  1. Open the dialog Options for Target — Debug.

    Select as the debugger adapter

  2. Enable Use, select ULINK Cortex Debugger, and click Settings to open the Target Driver Setup dialog.

    Configure the Serial Wire Debug mode

  3. Enable SWJ and select SW.
  4. Click the Trace tab.

    Set the Serial Wire Trace options

  5. Set Trace Enable and Autodetect.
  6. The Core Clock must correspond to the device configuration.

Start the debugging session and verify the captured trace data with a µVision window.


  • Always synchronize the settings in the *.ini file with the settings in the Target Driver Setup—Trace Port dialog.
  • Use the examples delivered with the Keil board MCBSTM32E as a reference.
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