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ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Wed Jul 23, 2025 12:20 am
by alplayer01
Hello,
I am designing a Basic PCB at the moment using the ESP32-C3-WROOM-02-N4
I am wondering, how to design the board in such a way, that I am able to upload my code without pressing the boot and enable buttons (without using an external USB to Serial CP2102 or similar) ?
Attached: Schematic.
Thank you.
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Sun Jul 27, 2025 9:31 am
by ves011
I guess you already found the answer
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Mon Jul 28, 2025 9:55 pm
by alplayer01
I guess you already found the answer
Not really.
I made a research before coming here. some say that there is an auto-reset circuit, and you don't need to hold the BOOT button at all, others insist that you need to press BOOT at power-on/reset.
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Tue Jul 29, 2025 2:19 am
by Sprite
For the USB-serial-JTAG converter you don't need an external reset circuit, the thing implements that internally. Your schematic as it is should be good to go. You do want to make sure you make GPIO9 accessible from somewhere, as you want to be able to put the chip into download mode manually for the first flash and if you mess up your firmware by disabling the USB-serial-JTAG converter somehow.
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Tue Jul 29, 2025 6:47 am
by alplayer01
For the USB-serial-JTAG converter you don't need an external reset circuit, the thing implements that internally. Your schematic as it is should be good to go. You do want to make sure you make GPIO9 accessible from somewhere, as you want to be able to put the chip into download mode manually for the first flash and if you mess up your firmware by disabling the USB-serial-JTAG converter somehow.
Oh, the first flash is the most important one. its actually going to be for a commercial product. the contract manufacturer needs to flash multiple chips at the same time.. having to press buttons is not practical at all. Should we add a 5-pin header having 5v,gnd,d+/d-/gpio9 (in which gpio9 is directed to gnd once it is plugged in), or that wont work? would appreciate any suggestions.
Thanks.
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Tue Jul 29, 2025 9:30 am
by Sprite
That would work. If you're developing that anyway (and have enough GPIOs free), also put EN, RX and TX on that connector, in case the contract manufacturer prefers serial over USB. Also, if you're interested, Espressif also sells ESP32 modules preprogrammed with your firmware of choice (if you buy more than a certain MOQ, iirc something like a few thousand) if you don't want to bother.
Re: ESP32-C3-WROOM-02-N4 Automatic Upload
Posted: Tue Jul 29, 2025 11:49 am
by alplayer01
That would work. If you're developing that anyway (and have enough GPIOs free), also put EN, RX and TX on that connector, in case the contract manufacturer prefers serial over USB. Also, if you're interested, Espressif also sells ESP32 modules preprogrammed with your firmware of choice (if you buy more than a certain MOQ, iirc something like a few thousand) if you don't want to bother.
Great. Thanks a lot for the suggestions!