Programming HTIT-WSL_V3 via UART0 Instead of USB-C

I am currently working with the HTIT-WSL_V3 ESP32 and am trying to flash the ESP32 using UART0 instead of the USB-C interface.

To test this setup, I’ve connected a USB-TTL converter to the TX/RX of UART0 between my computer and the ESP32, however I cannot find the DTR (Data Terminal Ready) and RTS (Request to Send) pins on the pin map of the HTIT-WSL_V3. ESP32 resources I’ve read seem to show that these pins will be required for the Arduino IDE to begin flashing the ESP32, is this true for your device and how would I be able to do so?

The best way is to manually put the device into bootloader mode but holding down USER button, then clicking the RST button and then releasing USER button. After that you can flash the device. You may need to hit RST again after flashing for it to restart, I’m not completely sure.
There is a possibility for an automated hack which needs lots of extra circuitry and isn’t easy, so I’d advice you to use the button-combo.

This is what the DTR/RTS signals do automagically for you - a convenience only but quite a handy one.

What’s wrong with the USB-C port?

Thanks for the reply!

I’m specifically trying to use UART0 for programming the HTIT-WSL_V3 to test different configurations in my setup. I’ve made a plastic enclosure to house the ESP32 and another PCB carrier board. With the current design I wouldn’t be able to access the USB-C port on the ESP32 without taking it out of the enclosure. I do have access to the UART0/1 lines through my PCB board.

The USB-C port works well and the button trick worked also, but I’m looking to reduce the need for additional cables to connect the USB-C and needing to press the button to trigger the DTR/RTS signals.

That’s no trick, or moon, it’s core functionality - the DTR/RTS is the “trick” here and is implemented on the board via the CP2102 USB to serial and the 2N7002BKS (which is a dual MOSFET chip that triggers the Boot & User lines in the correct sequence). The DTR/RTS lines aren’t broken out - there would not normally be a need as they are a by-product of another era that have been hijacked - they link straight from the CP2102 to the 2N7002.

The Boot and User lines are available on the header pins but this need you to get some wires out the box to some switches. Consider how often you may need to update the firmware - popping the top off to press the buttons every so often may not be that bad. If you are using WiFi you can also do OTA updates.

Welcome to the embedded design cul-de-sac where you drive rather a long way down it and then realise you’ve ended up somewhere less than ideal - happens to everyone at some point!

Okay I see, I’ll look into other options for updating firmware as well, but it seems the easiest solution would be to just open the enclosure and take the device out for updating, wouldn’t require much change to the design this way.

Thanks!