How many sensors can be supported by a single Arduino unit? I am a beginner in the Arduino world. I made some basic projects of the book that comes with the starter kit (it's was borrowed by a friend of mine) and also I used a humidity, a temperature sensors and a LCD display.

I want to buy an Arduino Uno for measure room temperature, humidity, carbon monoxide, carbon dioxin and maybe a couple more variables. I will to use 4 sensors, 1 buzzer, 1 LCD display and 1 ESP8266 serial WIFI wireless module.

After this work I will add for functionalities but as I have a lot of components I am not sure if the Arduino Uno can supports them because it has a limited quantity of pins.

Do I need an Arduino with more pins? what if I use all these pins and I need more? Can the Arduino Uno be expanded with more pins?

As the Arduino Uno is a very small computer, can its processor support all these components and their operations?
An Uno has more than enough pins for the devices you described.


A DHT22 Relative Humidity and Temperature sensor needs only one digital pin for both variables.
An MQ-7 Carbon Monoxide sensor needs one analog pin.
An MG-811 Carbon Dioxide sensor needs one analog pin (and an amplifier).
A Piezo buzzer needs one PWM pin.
The LCD with a Hitachi interface needs four digital pins.
The ESP module needs two digital pins.


That's 7 digital pins, one of which needs to be a PWM pin, and 2 analog pins. I did not make any choices about best or cheapest devices, just ones I either knew about or could find quickly by searching. But with this pin requirement doesn't come close to exhausting the available pins on an Uno so there's plenty of capacity left unassigned for you to make other choices that might require different interfaces or more pins.