ESP8266 Community Forum

- Sun Mar 01, 2015 5:19 am #11025 Hello to the graet forum,

I am using the wifi modele ESP-01 and I have conect it serial with max232 module (see attachement). I power the max232 with 3.3V.
It works great the serial connection between ESP & max232. I have already Flash the module with the NodeMCU firmware (nodemcu_20150212) and I can uplaod files to it.
I have made a board with the esp & max232 permanently related. When I do not need the serial connection I disconect the power supply of the max232(via jumpers). In that case the esp was not booting (not flash the blue light).
It seems to me that something happened with the resistive of Rx/Tx pins.

Please advice
Thanks

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- Tue Oct 27, 2015 10:32 am #32383 Did you have success with it?
I'm having trouble by connecting esp8266 through max232 to PC. I made an voltage divider between the tx from max to esp.
The esp don't respond to any AT commands. I observed that it's blue led stays always active, is it right?

- Mon May 30, 2022 3:54 pm #94655 To both of your questions
ESP-01 runs at 3.3V.
MAX2323 needs 5V

You can use a converter like AMS1117 to convert 5V to 3.3V and use input power of 5V with IC and output power of 3.3V with ESP-01. However, there is a chance of reverse current. So, simple solution would be:

Use MAX3232 instead of MAX2323 with ESP-01. MAX3232 can run on both 3.3V and 5V. Singularity of power is maintained.
OR
Use ESP8266/ESP32/D1 Mini kind of boards with MAX232. Both can operate at 5V. You will not even need a voltage converter.

Hope this helps!

Cheers!!!
HSA Shankar