ESP8266 Community Forum

- Tue Jun 16, 2015 3:16 am #20572 Hi,
I have a NodeMCU board (yellow, v0.9, 05/12/2014 release) and an Arduino Mega.
Can someone help please, how to connect the NodeMCU to the Arduino. I searched for hours by google, but didn't find the correct pin description about connect the board to Arduino.
The NodeMCU board is in AP mode. In "standalone" mode (connect only with USB to the PC) works fine. The IP adress has a respond in browser. ("Hello from ESP8266" ) In this case I used NodeMCU lua firmware with init.lua, but I got the same result with simply Arduino webserver code. (Standalone works in both case)

I had tried
devkit lower rigth corner 3.3V - Breadboard power supply 3.3V
devkit lower rigth corner GND - Breadboard power supply GND (Common with Arduino GND)
devkit RX - Arduino TX
devkit TX - Arduino RX

I didn't found the CH_PD pin on devkit, maybe the "EN" pin same as the CH_PD in other modules? What should I do to work together these devices?
I would like to measure and show the sensor values connected on Arduino Mega, (maybe on Thingspeak) and control the Mega GPIO pins.

Sorry for my bad english, I hope you will understand

- Tue Jun 16, 2015 3:53 pm #20626 Can answer some
EN is CH_PD Hold high with a resistor perhaps 1K to 10K
Make sure all the earths( GND) are linked together
power and GND you have right .
RX/TX is right as you will read serial output via Mega which has USB to PC right?
I put an Arduino example to connect to Thingspeak and Sparkfun and Ubidots and also how to email in the Wiki above

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Wed Jun 17, 2015 2:28 am #20664 Thanks for your help! I connected the devices as you described. "EN" pin has 4,7K resistor, TX/RX pins connect to Mega without resistor. All GND linked together, through Mega also.

Unfortunately, there is still no result My goal is to control the relays, and read DHT values remotelly that are connected to the Mega. I think it can be solved with passing parameters between serials.
I think the problem is in my sketches, because when I only devkit connect to the PC with USB, webserver example is working fine. Either NodeMCU or Arduino IDE example. (The strange thing that AT command doesn't working neither case! Maybe maybe I need to look for a solution here?)

I am uncertain, what code should I use on devkit, and what code on Mega. Can you a little more help with this?

- Wed Jun 17, 2015 3:21 am #20670 Some additional info:
Based on this I created a little Thingspeak board, working fine. DHT connected to NodeMCU devkit directly. I need same solution, but the DHT and devkit connected to Mega.