ESP32 Forum

I recently had someone design a board for me that uses a ESP32-WROOM-32D and a FT232R USB to UART chip.
The idea was to make the board in such a way that it would be programmable using the EspTool.

Unfortunately, I'm unable to program the board. The only way I can program the board is by manually connecting GPIO0 to ground en than resetting the board (by connection EN to ground shortly)

According to the designer, this should not be necessary.

This is what the ESP and FT232R part of the circuit looks like:
There's no connection between EN/GPIO0 and the FT232R.
Most ESP32 board use DTR/RTS from the USB to UART chip to start the ESP32 in programming mode, I believe, usually with a schema like this:
But according to the designer, this should not be necessary when using the FT232R.

Can anybody give me advice on whether or not the extra piece of circuit using DTR and RTS is required to program the board?

You are right, he is wrong.

The esp32 needs a signal on GPIO0 to enter firmware download mode, and a toggle on EN/RESET to reset it and enter download mode. The FT232R could not magically do that over the TX/RX lines. Sorry, your designer was mistaken. Take a page from the many esp32 dev boards, use that auto flash circuit.

I like to use a part like UMH3N, the two transistors and resistors are in a single package, so it's just a single component to implement the auto flash function:

Huh, that's a cute part; stashing that in the mental database for the next time I need it. Thanks for bringing it up.

Thanks for the clarification!

The UMH3N looks like a great part to save some space, will give it a try!

becorey wrote: ↑

Tue Mar 02, 2021 12:06 am

The esp32 needs a signal on GPIO0 to enter firmware download mode, and a toggle on EN/RESET to reset it and enter download mode. The FT232R could not magically do that over the TX/RX lines. Sorry, your designer was mistaken. Take a page from the many esp32 dev boards, use that auto flash circuit.

I like to use a part like UMH3N, the two transistors and resistors are in a single package, so it's just a single component to implement the auto flash function:

Better than my fellow BC847BS for almost the same price!