esp-idf/docs/esp32.cfg

#
# Example configuration file to hook up an ESP32 module or board to a JTAG 
# adapter. Please modify this file to your local setup.
#
#


# Include the configuration for the JTAG adapter. We use the Tian TUMPA here.
# If you have a different interface, please edit this to include the 
# configuration file of yours.
source [find interface/ftdi/tumpa.cfg]

# The ESP32 only supports JTAG.
transport select jtag

# The speed of the JTAG interface, in KHz. If you get DSR/DIR errors (and they
# do not relate to OpenOCD trying to read from a memory range without physical
# memory being present there), you can try lowering this.
adapter_khz 200

# With no variables set, openocd will configure JTAG for the two cores of the ESP32 and
# will do automatic RTOS detection. This can be be adjusted by uncommenting any of the
# following lines:

# Only configure the PRO CPU
#set ESP32_ONLYCPU 1
# Only configure the APP CPU
#set ESP32_ONLYCPU 2
# Disable RTOS support
#set ESP32_RTOS none
# Force RTOS to be FreeRTOS
#set ESP32_RTOS FreeRTOS

#Source the ESP32 configuration file
source [find target/esp32.cfg]


# The TDI pin of ESP32 is also a bootstrap pin that selects the voltage the SPI flash
# chip runs at. When a hard reset happens (e.g. because someone switches the board off
# and on) the ESP32 will use the current TDI value as the bootstrap value because the
# JTAG adapter overrides the pull-up or pull-down resistor that is supposed to do the
# bootstrapping. These lines basically set the idle value of the TDO line to a 
# specified value, therefore reducing the chance of a bad bootup due to a bad flash
# voltage greatly.

# Enable this for 1.8V SPI flash
esp108 flashbootstrap 1.8
# Enable this for 3.3V SPI flash
#esp108 flashbootstrap 3.3