I'm currently looking to buy an Arduino, but never touched robotics before. Would anyone be able to give me an idea how many pins a sensor such a magnetometer would use? This is for Arduino Uno.

Sorry if this is stupid, just really have no idea how to approach Arduino design without having one here and can't get one for a few weeks at the least.


5 Answers 5


Below image is the answer to your question.


According to this image, magnetometer required four pins of arduino.

GND of magnetometer ----> Arduino GND

Vcc of magnetometer ----> Arduino 3.3 Volt

SDA of magnetometer ----> Arduino Analog Pin 4

SCL of magnetometer ----> Arduino Analog Pin 5

I hope it will help you.


Would anyone be able to give me an idea how many pins a sensor such a magnetometer would use?

Here below image provides the connection and pin requirements for magnetometer...


According to image magnetometer will require 4 pins of Arduino 2 pins of supply i.e +3 volt and Ground and other two pins will be any two Analog pins of Arduino.

And to connect other sensors with Arduino, you can find datasheet of desired sensor and can find how many pins that sensor is going to use.


How many pins are needed for a sensor?

As many pins as are needed for that sensor.

Every sensor is different. The datasheet or manual for the sensor or the chip or other device that the sensor is based around will tell you how the interface to it works - what each pin does, how you use it, etc.

It is up to you to read that documentation and learn how the sensor works to then be able to plan how best to connect it to your Arduino.

Some sensors require specific connections, such as the two I2C pins in your example sensor. Others may need the SPI pins. Then there are sensors that use analog inputs. That may be one pin for, say, an LDR, or three pins in the case of a 3-axis accelerometer.

In short: RTFM.


One, maybe two. It's impossible to say for sure without a concrete example.

I would recommend looking up the type of sensor(s) you want to use, and read the data sheet(s). Things you'll want to consider are things like operating voltage (3.3v or 5v), current draw (>40mA?), are any additional passive components required (capacitors, resistors, ...), etc.

Data sheets will describe in great detail, how to use a specific device.

  • If you are satisfied with this answer, it's good form to select it and indicate your question as answered :)
    – Mazaryk
    Mar 20, 2017 at 5:15

Broadly speaking, look for sensors/outputs that use I2C or SPI interfaces. If you use I2c, you can wire all your sensors with two digital pins. This is especially important with multi-axis sensors that would otherwise chew up 3-6 pins each.

I2C is probably easier because SPI need one extra pin per device, in addition to the 2 base pins. Still, that's about 10 devices on one UNO, IF you spend the extra $1 or $2 on the SPI/I2C sensors/LCDs/etc instead of going for what at first seems like a cheaper part.

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