Serial communication to Blynk

Hi, i want to ask is it possible to use serial communication from arduino uno to nodemcu(esp8266) and then upload it to Blynk from nodemcu?

Yes, but why not just run your sketch on your Nodemcu? Why do you need the Arduino Uno?

It is possible, but very difficult to achieve because of timing issues.

You’d probably be better running the code directly on the NodeMCU and doing away with the Uno, or using an ESP32 if you need more pins or more analog inputs.

Alternatively, you could look at Blynk MCP


Because when I connect ultrasonic sensor to nodemcu, the readings is not accurate and not consistent. But when I connect it to Arduino Uno, the reading is just fine.

Ultrasonic sensors work fine with the NodeMCU. It’s probably something to do with your code, your choice of pins, or the way that you’ve powered the sensor - but it’s impossible to say which without more info.


In my ye olde project from 2017 I had to do something similar to be able to constantly listen for (after? to? Help me out here Pete, you know I’m from Sweden! :smiley: ) 433 Mhz radio signals/data bursts.

Basically, I sent data from one UNO (the “radio slave”) to another UNO (the one with Blynk stuff) which has a RX buffer, and then checked for new data once every second. No timing issues there… or am I missing something?

The ye olde project:

Of course not, but Blynk newbies could easily get in a mess waiting for serial data and omitting to service the Blynk library with a command.

Your “ye olde project” :grinning: is also a bit of an overkill as far as hardware is concerned though.
I still use 433MHz quite a bit, because we have some window blinds that operate on that frequency, and I also like to use 433MHz keyfobs and stand-alone pushbuttons because of their long battery life, range, and compact size.
I use a single Wemos D1 Mini with 433 Tx and Rx modules connected to it as my 433MHz bridge device. I don’t run Blynk on it, because its part o my Node-Red/MQTT setup, but it would work just fine with Blynk. This makes the whole thing smaller than one Uno, and I don’t have to worry about sending data from one device to another over serial comms.


Ah… THEM! :laughing: But I get your point!

A proverb from an ye olde Englishman: " Whatever is worth doing at all, is worth doing well " hehe :wink:

Don’t forget, I was a Blynk newbie myself at the time :shushing_face: Starting with limited programming skills and exactly zero experience working with MCU’s, I’m quite happy how my project turned out! :slight_smile:

I still like 433 MHz gadgets. It’s simple, it’s cheap, it’s easy to integrate. And no, I wouldn’t use an UNO today. :stuck_out_tongue:

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