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Driving me crazy the ESP2866

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be80be

Well-Known Member
I guess this is as good of place to talk about this. Here we go the esp2866 has snapback i/O protection.
It's holding voltage is 5.8 volts it snaps out at 6.0 volts.
I have tested 3 of these at 5 volt to 3 volt on the RX pin only.
So it's TX at 5 volts to the esp2866 RX pin I installed a diode on the RX pin. I have tested this with a Ch340g
for with 5 volts and 3.6 it was closer to 3.7 volts but it's close enough to get a idea of what works and what don't.
ESP2866.png
Now with my scope I get a .7 volt drop on the RX side of the esp2866 so it's being clamped to the esp2866 voltage of 3.3 volts.
That works great for sending data at high speed it worked up to the full speed of the chip
Now I at first mistakenly hooked the CH340g to a 3.6 volt supply that dropped the RX to 3.0 volts and the esp2866 couldn't receive data.
I could not load new Lua commands.
So this post is to see what people think is going on here.
I think the diode is just dropping the voltage on the TX pin to 4.3 my scope shows that.
And that is in turn clamped with the protection diode on the esp2866 RX pin it works great that way.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Why not use an FTDI board or lead?, the RX/TX are 3.3V and you can use a 3.3V regulator to feed the ESP from the 5V USB supply (the FTDI 3,3V supply can't provide enough current for the ESP).

That's what I'm using.
 

be80be

Well-Known Member
I use the ch340g at 3.3 volts without the diode but I'm pretty sure the diode does what i think.
 
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