Configure Other JTAG Interfaces

[中文]

For guidance about which JTAG interface to select when using OpenOCD with ESP32-S31, refer to the section Selecting JTAG Adapter. Then follow the configuration steps below to get it working.

Configure eFuses

By default, ESP32-S31 JTAG interface is connected to the built-in USB_SERIAL_JTAG peripheral. To use an external JTAG adapter instead, you need to switch the JTAG interface to the GPIO pins. This can be done by burning eFuses using idf.py tool.

  • Burning DIS_USB_JTAG eFuse will permanently disable the connection between USB_SERIAL_JTAG and the JTAG port of the ESP32-S31. JTAG interface can then be connected to GPIO54-GPIO57. Note that USB CDC functionality of USB_SERIAL_JTAG will still be usable, i.e., flashing and monitoring over USB CDC will still work.

  • Burning JTAG_SEL_ENABLE eFuse will enable selection of JTAG interface by a strapping pin, GPIO37. If the strapping pin is low when ESP32-S31 is reset, JTAG interface will use GPIO54-GPIO57. If the strapping pin is high, USB_SERIAL_JTAG will be used as the JTAG interface.

Warning

Burning eFuses is an irreversible operation, so please consider the above option before starting the process.

Configure Hardware

  1. Identify all pins/signals on JTAG interface and ESP32-S31 board that should be connected to establish communication.

    ESP32-S31 pins and JTAG signals

    ESP32-S31 Pin

    JTAG Signal

    MTDO / GPIO54

    TDO

    MTDI / GPIO56

    TDI

    MTCK / GPIO55

    TCK

    MTMS / GPIO57

    TMS

  2. Verify if ESP32-S31 pins used for JTAG communication are not connected to some other hardware that may disturb JTAG operation.

  3. Connect identified pin/signals of ESP32-S31 and JTAG interface.

Configure Drivers

You may need to install driver software to make JTAG work with computer. Refer to documentation of your JTAG adapter for related details.

On Linux, adding OpenOCD udev rules is required and is done by copying the udev rules file into the /etc/udev/rules.d directory.

Connect

Connect JTAG interface to the computer. Power on ESP32-S31 and JTAG interface boards. Check if the JTAG interface is visible on the computer.

To carry on with debugging environment setup, proceed to section Run OpenOCD.

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