What would I need to enable flashing to a ESP32-WROOM-32

[jimhelios]

Sorry to bump an old thread, but I don't understand the circuit posted by username. It seems if RTS is brought low, then EN will be pulled low through the transistor, but GPIO will remain pulled high because that transistor is now off. If DTR is brought low then GPIO_0 is pulled low as long as RTS is high. But if RTS is high then GPIO_0 can not go low.

So how does this circuit pull both EN and GPIO_0 low at the same time? I'm sure I'm missing it, if someone could explain I would appreciate it. The circuit with the manual buttons is very clear.

Thanks...

[johntaves]

Is there a simplification/overview of all this?

Maybe this is the programmer https://www.amazon.com/ACROBOTIC-Progra ... B07G2256WK

If so, then what is the schematic that goes with the ESP32-WROOM-32?

thanks,

jt

[username]

What is not shown on that schematic is the rest of the circuit. There is a 0.15uf cap on EN line to gnd.
Basically, RTS goes low & DTR high pulling EN to gnd. Then they flip. RTS high & DTR low, pulling GPIO0 low. Since there is a cap on EN to gnd its still in the low state, so when it comes out of reset it sees that GPIO0 is low and puts it into programming mode.

As for the amazon link that programmer will not work.

Also, that schematic I provided is on most ESP32 boards. The only real difference is that I used a part with both transistors in one package vs individual ones.

[johntaves]

Sorry for being thick, but are you referring to the circuit with the FT231XQ-R, or the simpler one after that? If the later, then what is the programmer to buy?

I don't want to put the usb -> serial circuit on my board. It will only be used once. Isn't there a reference design and a programmer to go with it?

Thanks for your help.

[username]

This is what you want.
They are sold at many places. Here are just a few
https://www.digikey.com/en/products/det ... B5AOINGQA
https://www.gridconnect.com/products/es ... gging-tool

https://www.electrodragon.com/product/e ... 266-esp32/