I use the RTC GPIO wake on an ESP32-C6, set up like:

esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);
rtc_gpio_pullup_en(GPIO_CTRL_WAKE);
rtc_gpio_pulldown_dis(GPIO_CTRL_WAKE);
esp_sleep_enable_ext1_wakeup_io(1 << GPIO_CTRL_WAKE, ESP_EXT1_WAKEUP_ANY_LOW);


I also set esp_sleep ...

I had this problem and solved it by using gpio_config()

I believe the problem is due to the default IOMUX for these "pins" being MTMS/MTDI (see section 2 in the datasheet). gpio_config() changes this to "F1".

Same effect for GPIO 6 and 7.

Update -
So... I decided to add minimal components to the custom board, and to add components progressively.

Initially, within absolute minimum, JTAG over USB worked.

Adding an external 32kHz crystal and associated capacitors BROKE JTAG. At this point, "sdkconfig" was left with default RTC ...

RS232 is an electrical standard which is one way the 0/1 bits are encoded. Often we use "TTL" encoding. The underlying UART messages are the same.
People often fail to make the distinction, and confuse themselves and others...
If you REALLY want RS232 you'd probably use a MAX3232 to interface ...

I suspect you have misunderstood the "12v" designation for the relay. I would expect that to be the relay coil voltage. If you are supplying it with 5V, there will probably be insufficient "pull" from the relay coil to close the load contacts.

Can you hear the relay "clicking". It should be strong ...

Using a test program which can be programmed over the USB to built-in JTAG adapter on an ESP32-C6-DevkitC-1 without any issue, I cannot get it to work on a custom board using an ESP32-C6-WROOM-1 module. Devkit is 8M flash and wroom is 4M flash.

I am using VSCode with the official Espressif ...

@xryl669 - did you make working code to read ADC from the wake-up stub?

I cannot make it work!

It would be good to check whether the device is running on a "coin cell", e.g. during battery change, and abort a HP wake-up if so.

The M24M02 EEPROM (2Mbit, so 18 bit address space) includes the top two address bits as part of the device address. Only a 16 bit address is sent as "data".

An ugly way to deal with this would be to register all four of the "device addresses" using i2c_master_bus_add_device() and to write ...