Configure WROVER JTAG Interface

All versions of ESP32 WROVER KIT boards have JTAG functionality build in. Putting it to work requires setting jumpers to enable JTAG functionality, setting SPI flash voltage and configuring USB drivers. Please refer to step by step instructions below.

Configure Hardware

  1. Enable on-board JTAG functionality by setting JP8 according to ESP-WROVER-KIT V4.1 Getting Started Guide, section Setup Options.

  2. Verify if ESP32 pins used for JTAG communication are not connected to some other h/w that may disturb JTAG operation:

      ESP32 Pin JTAG Signal
    1 CHIP_PU TRST_N
    2 MTDO / GPIO15 TDO
    3 MTDI / GPIO12 TDI
    4 MTCK / GPIO13 TCK
    5 MTMS / GPIO14 TMS

Configure USB Drivers

Install and configure USB drivers, so OpenOCD is able to communicate with JTAG interface on ESP32 WROVER KIT board as well as with UART interface used to upload application for flash. Follow steps below specific to your operating system.

Note

ESP32 WROVER KIT uses an FT2232 adapter. The following instructions can also be used for other FT2232 based JTAG adapters.

Windows

  1. Using standard USB A / micro USB B cable connect ESP32 WROVER KIT to the computer. Switch the WROVER KIT on.

  2. Wait until USB ports of WROVER KIT are recognized by Windows and drives are installed. If they do not install automatically, then then download them from http://www.ftdichip.com/Drivers/D2XX.htm and install manually.

  3. Download Zadig tool (Zadig_X.X.exe) from http://zadig.akeo.ie/ and run it.

  4. In Zadig tool go to “Options” and check “List All Devices”.

  5. Check the list of devices that should contain two WROVER specific USB entries: “Dual RS232-HS (Interface 0)” and “Dual RS232-HS (Interface 1)”. The driver name would be “FTDIBUS (vxxxx)” and USB ID: 0403 6010.

    Configuration of JTAG USB driver in Zadig tool

    Configuration of JTAG USB driver in Zadig tool

  6. The first device (Dual RS232-HS (Interface 0)) is connected to the JTAG port of the ESP32. Original “FTDIBUS (vxxxx)” driver of this device should be replaced with “WinUSB (v6xxxxx)”. To do so, select “Dual RS232-HS (Interface 0) and reinstall attached driver to the “WinUSB (v6xxxxx)”, see picture above.

Note

Do not change the second device “Dual RS232-HS (Interface 1)”. It is routed to ESP32’s serial port (UART) used for upload of application to ESP32’s flash.

Now ESP32 WROVER KIT’s JTAG interface should be available to the OpenOCD. To carry on with debugging environment setup, proceed to section Run OpenOCD.

Linux

  1. Using standard USB A / micro USB B cable connect ESP32 WROVER KIT board to the computer. Power on the board.
  1. Open a terminal, enter ls -l /dev/ttyUSB* command and check, if board’s USB ports are recognized by the OS. You are looking for similar result:

    user-name@computer-name:~/esp$ ls -l /dev/ttyUSB*
    crw-rw---- 1 root dialout 188, 0 Jul 10 19:04 /dev/ttyUSB0
    crw-rw---- 1 root dialout 188, 1 Jul 10 19:04 /dev/ttyUSB1
    
  2. Following section “Permissions delegation” in OpenOCD’s README, set up the access permissions to both USB ports.

  3. Log off and login, then cycle the power to the board to make the changes effective. In terminal enter again ls -l /dev/ttyUSB* command to verify, if group-owner has changed from dialout to plugdev:

    user-name@computer-name:~/esp$ ls -l /dev/ttyUSB*
    crw-rw-r-- 1 root plugdev 188, 0 Jul 10 19:07 /dev/ttyUSB0
    crw-rw-r-- 1 root plugdev 188, 1 Jul 10 19:07 /dev/ttyUSB1
    

    If you see similar result and you are a member of plugdev group, then the set up is complete.

    The /dev/ttyUSBn interface with lower number is used for JTAG communication. The other interface is routed to ESP32’s serial port (UART) used for upload of application to ESP32’s flash.

Now ESP32 WROVER KIT’s JTAG interface should be available to the OpenOCD. To carry on with debugging environment setup, proceed to section Run OpenOCD.

MacOS

On macOS, using FT2232 for JTAG and serial port at the same time needs some additional steps. When the OS loads FTDI serial port driver, it does so for both channels of FT2232 chip. However only one of these channels is used as a serial port, while the other is used as JTAG. If the OS has loaded FTDI serial port driver for the channel used for JTAG, OpenOCD will not be able to connect to to the chip. There are two ways around this:

  1. Manually unload the FTDI serial port driver before starting OpenOCD, start OpenOCD, then load the serial port driver.
  2. Modify FTDI driver configuration so that it doesn’t load itself for channel B of FT2232 chip, which is the channel used for JTAG on WROVER KIT.

Manually unloading the driver

  1. Install FTDI driver from http://www.ftdichip.com/Drivers/VCP.htm

  2. Connect USB cable to the WROVER KIT.

  3. Unload the serial port driver:

    sudo kextunload -b com.FTDI.driver.FTDIUSBSerialDriver
    

    In some cases you may need to unload Apple’s FTDI driver as well:

    sudo kextunload -b com.apple.driver.AppleUSBFTDI
    
  4. Run OpenOCD (paths are given for downloadable OpenOCD archive):

    bin/openocd -s share/openocd/scripts -f interface/ftdi/esp32_devkitj_v1.cfg -f board/esp-wroom-32.cfg
    

    Or, if OpenOCD was built from source:

    src/openocd -s tcl -f interface/ftdi/esp32_devkitj_v1.cfg -f board/esp-wroom-32.cfg
    
  5. In another terminal window, load FTDI serial port driver again:

    sudo kextload -b com.FTDI.driver.FTDIUSBSerialDriver
    

Note that if you need to restart OpenOCD, there is no need to unload FTDI driver again — just stop OpenOCD and start it again. The driver only needs to be unloaded if WROVER KIT was reconnected or power was toggled.

This procedure can be wrapped into a shell script, if desired.

Modifying FTDI driver

In a nutshell, this approach requires modification to FTDI driver configuration file, which prevents the driver from being loaded for channel B of FT2232H.

Note

Other boards may use channel A for JTAG, so use this option with caution.

Warning

This approach also needs signature verification of drivers to be disabled, so may not be acceptable for all users.

  1. Open FTDI driver configuration file using a text editor (note sudo):

    sudo nano /Library/Extensions/FTDIUSBSerialDriver.kext/Contents/Info.plist
    
  2. Find and delete the following lines:

    <key>FT2232H_B</key>
    <dict>
        <key>CFBundleIdentifier</key>
        <string>com.FTDI.driver.FTDIUSBSerialDriver</string>
        <key>IOClass</key>
        <string>FTDIUSBSerialDriver</string>
        <key>IOProviderClass</key>
        <string>IOUSBInterface</string>
        <key>bConfigurationValue</key>
        <integer>1</integer>
        <key>bInterfaceNumber</key>
        <integer>1</integer>
        <key>bcdDevice</key>
        <integer>1792</integer>
        <key>idProduct</key>
        <integer>24592</integer>
        <key>idVendor</key>
        <integer>1027</integer>
    </dict>
    
  3. Save and close the file

  4. Disable driver signature verification:

    1. Open Apple logo menu, choose “Restart…”

    2. When you hear the chime after reboot, press CMD+R immediately

    3. Once Recovery mode starts up, open Terminal

    4. Run the command:

      csrutil enable --without kext
      
    5. Restart again

After these steps, serial port and JTAG can be used at the same time.

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