ESP8266 Community Forum

- Fri Jan 01, 2021 4:17 am #90031 @schufti, yes m'y Arduino is in reset mode : the orange wire on the left connect the pins reset and gnd.

I found the last problem for enabling flashing / communicate with ESP : remove the resistors on Rx.
So the Rx channel is not in 3.3v anymore but in 5v.
I red that it can damage the ESP.

So before "resolving" this post, I have 2 last questions :
- is it really risky to let 5v for Rx channel, can it lower the life of my ESP?
- why the Rx channel is not working when I use 3 resistors to lower the voltage? And so, is there a way for lower the voltage to 3,3v on Rx?

- Mon Jan 04, 2021 2:33 am #90055 hello everyone.I have this problem too. I am using the esp-12e module. I set baud-rate to 115200. But it still doesn't update. (I ran this module before but then suddenly it started not responding to anything.)

- Mon Jan 04, 2021 8:12 am #90062 if only used during flashing the danger might be neglectable, but it might be even more reduced when jut using a series resistor (~3k3) to the exp rx pin to limit the "destructive overcurrent".
I can not identify the circuit you built with 3 resistors - I only know one with two.
its: arduino RX --- 2k2 ----- esp rx ---- 3k3 ----- gnd
totally correct would be via levelshifter

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- Tue Jan 05, 2021 12:50 pm #90089 Ok for the neglectable danger in flashing.

The circuit I built was like the first one you explained, just the resistor values changed :
Arduino Rx -- 10k -- esp Rx -- 10k -- 10k -- GND.
Or the same circuit but with 220 Ohms each.
So there's 2/3 of the voltage at esp (I think, but this may be wrong? Please correct me if necessary) : 5v * (2/3) = 3,3v.

As I just had my Arduino beginner's kit, so level shifter was not an option at this time. But if I can't do the same with resistors, I will consider to buy one.

I will try your circuit, with 2,2k and 3,3k to see the result.