ESP32-C3 pulls up GPIO19 because it is used by USB (IDFGH-7984)

[DCSBL]

Environment

• Development Kit: None
• Kit version (for WroverKit/PicoKit/DevKitC): na
• Module or chip used: ESP32-C3
• IDF version (run git describe --tags to find it): v4.4.1
• Build System: idf.py
• Compiler version (run xtensa-esp32-elf-gcc --version to find it): riscv32-esp-elf-gcc (crosstool-NG esp-2021r2-patch3) 8.4.0 (or xtensa-esp32-elf-gcc (crosstool-NG esp-2021r2-patch3) 8.4.0)
• Operating System: macOS
• (Windows only) environment type: Na
• Using an IDE?: VSCode
• Power Supply: external 5V

Problem Description

The GPIO pull-up configuration to configure GPIO19 does not work as expected.

Actual Behavior

After configuring gpio with the config below, the input is still pulled up.

gpio_config_t io_conf = {};
io_conf.pin_bit_mask = BIT64(GPIO_NUM_19);
io_conf.mode = GPIO_MODE_INPUT;
io_conf.pull_up_en = 0;
io_conf.pull_down_en = 0;
gpio_config(&io_conf);

To fix this, we have to clear the USB_SERIAL_JTAG_DP_PULLUP bit with CLEAR_PERI_REG_MASK(USB_SERIAL_JTAG_CONF0_REG, USB_SERIAL_JTAG_DP_PULLUP);. That works but only after a second reset. ->

https://www.espressif.com/sites/default/files/documentation/esp32-c3_datasheet_en.pdf page 21
USB - GPIO18 and GPIO19 are USB pins. The pull-up value of a USB pin is controlled by the pin’s pull-up value together with USB pull-up value. If any of the two pull-up values is 1, the pin’s pull-up resistor will be enabled. The pull-up resistors of USB pins are controlled by USB_SERIAL_JTAG_DP_PULLUP bit.

Expected Behavior

We expect that GPIO19 is put in the desired state without other config. Or that this, or 'a' workaround is documented somewhere (if that is not the case)

[DCSBL]

Thanks @zikalino !

[michaesc]

Does anyone happen to have a ESP-IDF (5.1.2 or similar) project that demonstrates (re)using the GPIO18 and GPIO19 of a ESP32-C3 for any simple purpose?

I'm trying to put a simple SPST tactical switch (push button) on each pin, which drives GPIO18 and GPIO19 low when pressed. The MCU should get an interrupt, but this is not happening. I'm not sure why, and I've written to the forum asking for help.

[wormyrocks]

Assuming you aren't using the USB JTAG feature, have you tried setting the eFuse bit for DIS_USB_SERIAL_JTAG?
espefuse.py -p COMx burn_efuse DIS_USB_SERIAL_JTAG 1
Anecdotally, it disables the pull-up on IO19 on boot, but I haven't tested whether I can subsequently reuse the pin as you describe.
Keep in mind it's a one-time programmable setting.

[michaesc]

I'm trying to not use the eFuse, in order to allow users to selectively disable USB-JTAG.

It makes no sense to me that the feature cannot be disabled, and worse yet there is no documentation stating whether it can or cannot be disabled. I'm still trying to debug the problem.