Can't get GPIO0 to work as OUTPUT

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Re: Can't get GPIO0 to work as OUTPUT

By QuickFix
- Sat Jun 30, 2018 2:59 pm #76747
Erik84750 wrote:Node MCU flash circuit: can you provide a link please? Thank you.

The image itself is rather large, so to prevent it clogging up the entire schreen, here's a simple link to the full schematics of the NodeMCU board.
It's the bit in the middle where it says: "USB to UART". :idea:

You could have found it (anyway, I did) on the Github-pages that go with it.
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Re: Can't get GPIO0 to work as OUTPUT

By McChubby007
- Sat Jun 30, 2018 3:10 pm #76748
Erik84750 wrote:Node MCU flash circuit: can you provide a link please? Thank you.

I use a board wired like this, which you supply 5v and the UART signals via a separate USB-TTY converter. Ignore the LEDs and photocell...

Not sure if that's what you wanted.
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Re: Can't get GPIO0 to work as OUTPUT

By McChubby007
- Sat Jun 30, 2018 4:17 pm #76751
McChubby007 wrote:
Erik84750 wrote:Node MCU flash circuit: can you provide a link please? Thank you.

I use a board wired like this, which you supply 5v and the UART signals via a separate USB-TTY converter. Ignore the LEDs and photocell...

Not sure if that's what you wanted.

Actually, it's probably not what you want as it has no automatic reset so best to go with the nodemcu schematic which was added just before my post was done.
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Re: Can't get GPIO0 to work as OUTPUT

By Erik84750
- Sun Jul 01, 2018 9:45 am #76759 Hi, in fact it is what I had expected to see, the issue I have with this circuit is that both DTR and RTS are needed. In my circuit I can just plug in an FTDI serial programmer (which does not have a RTS output pin), use its DTR: press Arduino IDE download button and off goes the programming download, after which it's ready to test right away; no hassles with wires or switches; no transistors etc...

I just now tested a manual download on a brandnew ESP8266-12F, tested the GPIO0 output loaded with 10k pullup and a 50R to a N-ch mosfet gate: oscillations!
When removing pullup and load, the output stays low! I thought there is an internal pullup to GPIO0?
Last edited by Erik84750 on Sun Jul 01, 2018 10:23 am, edited 1 time in total.
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