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Logging to Serial Port

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Maxime Vincent edited this page Mar 10, 2024 · 2 revisions

It is possible to enable logging to a serial port (Referred to as a "COM" port on Windows)

XLAT will output the measurements in a CSV-format, with 4 columns in the form of count;latency_us;avg_us;stdev_us.

To enable this functionality, the internal Virtual COM Port feature of the embedded J-Link debugger has to be enable.

  1. Make sure the STLink is converted to a J-Link, by re-flashing its firmware. (See Converting ST-LINK On-Board Into a J-Link)

  2. Start the J-Link Configuration tool, find your "J-Link STLink" debugger, right click it and select "Configure":
    image

  3. Under "Virtual COM port", select "Enable" and confirm with "OK". You might have to unplug and re-plug the USB connected after this change.
    image

  4. After this, a new "COM" port should appear in the Windows Device Manager (or a ttyACM device under Linux). Remember the port number.

    [53144.471802] usb 3-2.1: new full-speed USB device number 28 using xhci_hcd
[53144.601437] usb 3-2.1: New USB device found, idVendor=1366, idProduct=0105, bcdDevice= 1.00
[53144.601446] usb 3-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[53144.601451] usb 3-2.1: Product: J-Link
[53144.601453] usb 3-2.1: Manufacturer: SEGGER
[53144.648557] cdc_acm 3-2.1:1.0: ttyACM0: USB ACM device

  5. Use any terminal software capable of connecting to a serial port. E.g.:

  1. Configure the terminal application with following settings: 1000000 8N1

    • Baudrate: 1000000 (1M)
    • Databits: 8
    • Stop bits: 1
    • Parity: None
    • Flow control: None

    image

  2. You should see XLAT output appearing on the terminal:
    image

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