When it comes to the world of practical electronics very rarely will you find someone who doesn’t start their learning process with Arduino. In this article, let me cover some very frequently raised queries that arise when Arduino and Raspberry Pi are discussed together starting from do Arduino sensors work with Raspberry Pi.
Now I am an electronics engineer and in my college days I went even basic.
Arduino is this incredible module which makes everything relatively easy to understand.
The I/Os are pretty clear, there are libraries neatly available which are constantly maintained and upgraded, the Arduino software is perfect and easy to learn (provided you know a basic programming language like C), there are simulators and there is just ton of help available online and otherwise.
So, if looking at electronics components gets your juices flowing like me, the only thing that is stopping you is you, my lad.
The point I am making is, I started things from the very core.
Even though I had access to Arduino board, I rather chose a bare Atmega8L chip, learnt everything about it and created custom PCBs to handle the task I wanted the project to do.
When you approach things from the very base, from the very core, you tend to learn more which otherwise gets skipped if just want to get things done using shortcuts.
Today I am going to share a few of those learnings here such that my insights will help resolve any query you might be having when your look at Arduino and Raspberry Pi from a comparative perspective.
So, let me start with the one I get asked the most
Do Arduino sensors work with Raspberry Pi?
The answer is, they can, provided you take care of two things. First, is you must know that Raspberry Pi doesn’t accept analog inputs and therefore, you need to use an intermediate device like an ADC and secondly if you are using a digital sensor its input to Raspberry Pi should be less than 3.3V as that is the voltage level at which the Raspberry Pi operates.
So that is the gist of it. You can use the sensors that you use for your Arduino projects provided you are taking care of the interface requirements.
If I am being honest, that answer shouldn’t satisfy you.
Things already get a bit complicated with practical electronics (especially so if you are a beginner) and I think a broader outlook will be required to completely understand the topic.
Not to mention, it’s important to address lingering doubts and questions that germinate when you are done with your main question which in our case is do Arduino sensors work with raspberry pi.
So, I will cover the relationship of sensors when operating in conjunction with Raspberry Pi (and Arduino) so that you have a broader understanding in the matter and are then well on your way to interface sensors of your pick with your favorite controlling device.
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How To Connect Sensors To Raspberry Pi?
Now that we have established that you can in fact interface the sensors you use with your Arduino projects, the next logical question that stands is how exactly can you interface an analog sensor with Raspberry Pi.
There are a few ways you can do it and what way you choose to go with will depend upon your situation.
For example, let’s say you are creating a simple circuit where you just wish to take an indication whether pressure is applied or not on your pressure sensor.
In simplistic situations as these all you really need is a potential divider circuit that inputs highs (3.3 V) or lows (~0.3 V) on your Raspberry Pi’s GPIO pin and most of your work will be over.
However, if for example, you also wish to receive the output from a sensor and use it to actuate another device or at the very least numerically figure out for example how much pressure is applied you will need an intermediate analog to digital converter.
It isn’t as difficult as it sounds to be honest.
Let me briefly explain each of these scenarios,
Interfacing Sensor Directly To Raspberry Pi
Now there is a simple way to interface a sensor (let’s take the example of a pressure sensor) to Raspberry Pi which I am going to explain below.
In this simple arrangement, what you be able to do is sense if enough pressure is being applied or not on the pressure sensor.
You will be able to identify if the pressure is available or not (high and low signal) and use the identification to drive other processes using simple code logic.
For example, if pressure is available switch the LED on or display a message etc.
Using A Resistor
We can accomplish this using a resistor connected across the pressure sensor (or any sensor of your choice) and the GROUND pin of Raspberry Pi as shown.
As you can see the circuit is pretty straightforward and you can be ready with it in no time.
What is happening here is the 1M resistor that we are using is going to act as a voltage divider which divides the voltage extracted from the Raspberry Pi’s 3V3 pin.
Whenever, some significant pressure is applied on the pressure sensor, the voltage developed across the resistor (because the sensor acts as a short when some pressure is applied) which will be under 3.3 V will send a high signal to the Pin 7 (GPIO4) and thus Raspberry Pi will be able to identify that pressure is being applied.
As I said this is a simplistic circuit, which is kind of like answering the a Yes, No question.
Now what if you wish to push it a little further.
Using A Capacitor
If you use a capacitor in the circuit in the place of resistor with everything else remaining the same, something very interesting happens.
The inherent capability of a capacitor is that it gradually charges to its peak voltage capacity and then similarly it gradually discharges to its neutral position.
This time lag in charging and discharging can be made use of in gauging what is the current pressure that is applied on the pressure sensor.
So instead of just a yes, no answer you will also be able to make your answer more subjective by knowing what is the amount of pressure that is being applied on your sensor.
Now, of course the value wouldn’t be as accurate as you would get from an analog-to-digital converter.
But I think the circuit can come in handy if accuracy isn’t the top priority but you still would like to measure the force applied.
So, by using the capacitor in series with the pressure sensor you can figure out the resistance generated by the pressure sensor.
Higher the pressure applied lower will be the resistance generated.
Here is the schematic for the arrangement.
With this kind of arrangement where we are replacing a resistor with a capacitor should give you a greater degree of flexibility in your output.
You will now be able to gauge with fair amount of certainty what is the amount of pressure that is applied on the sensor.
Those were the basic ways of interfacing sensor that you normally use with Arduino with Raspberry Pi.
Let’s get our geek freak on now!
Interfacing Sensor Using An Analog To Digital Converter To Raspberry Pi
The methods I shared above are simple, fast and should get your job done.
But here is the thing they aren’t as effective as you would want them to be especially if you are working on projects that require precision.
Interfacing an analog-to-digital converter will give you a greater degree of accuracy to gauge the exact value coming from a sensor.
You may be thinking why do I need to use an ADC with raspberry pi, I didn’t feel the need to interface another piece of circuitry with Arduino.
That is because Raspberry Pi being a digital computer does not have any way of reading analog signals.
Contrast this to your usual AVR or PIC controllers which have as many as 6 pins that are capable of receiving analog inputs.
So, in order to make our Raspberry Pi analog friendly we will need to use an ADC like the MCP3008.
For the purpose of making the post thorough, diverse and easy to understand I will vary the input to the ADC using a simple potentiometer.
You can replace the potentiometer with any analog sensor you may be deploying in your project, the basic concept will remain the same.
Using an ADC like the MCP3008, you will be able to extract variable values from your sensor (potentiometer in my case).
This kind of arrangement becomes particularly useful if you are creating a multi-variate project where you want different things to happen at different sensor values.
MCP3008 has the capacity to receive 8 analog inputs as you can see in the pin diagram below.
So, it is a worthy addition to your arsenal if you wish to interface sensors like thermistors, load cells, accelerometers etc.
Here is the spec sheet of MCP3008 if you wish to know about the ADC in great details.
Let me just briefly put forth the different connections you will have to establish to make the arrangement work.
Provide power to the MCP3008 using VDD and DGND (digital ground). DOUT is the data out from MCP3008 and similarly DIN will be input from Raspberry Pi. Your sensor or the source of analog input (potentiometer) will get connected to pin 1 or CH0.
AGND or analog ground gets connected to GND and VREF which is used to change scales gets connected to 3.3 V because that us the scale that we want.
All in all, this is the summary of all the connections in and out of MCP3008.
- VDD – 3.3V
- VREF – 3.3V
- AGND – GND
- CLK – SCLK (GPIO11-Pin 23)
- DOUT – MISO (GPIO9-Pin 21)
- DIN – MOSI (GPIO10-Pin 19)
- CS – CE0 (GPIO8-Pin 24)
- DGND – GND
Here is the complete schematic of the described arrangement.
With a circuit like this, you will have this enhanced flexibility to measure what is the exact value of a variable analog input provided by a potentiometer or a sensor.
In addition to flexibility, you will have more precise measurements and you can use this kind of circuitry to drive different outputs depending on different input you get from your sensor.
When To Use Arduino Or Raspberry Pi?
Alright, we have now seen how you can interface the sensors that you use for your Arduino projects with Raspberry Pi.
But when it comes to practical electronics questions such as can something be done isn’t really as important as questions like how effectively can the task at hand can be done.
I hope you understand why am I putting this perspective.
Because as an engineer or someone who understands electronics, we know there are more than a few obvious ways of doing something.
For example, you can create a continuous clock using a basic 555 timer circuitry and you don’t necessarily need to deploy a microcontroller to do it.
Similarly, when a task demands to carry out multi-variate tasks like measuring and monitoring different physical parameters of for example a valve and display it in forefront, an embedded system with an Arduino connected to relevant sensors and an LCD display is probably appropriate.
But if you also want to for example send engine parameters of a racing vehicle via overhead networks to different support teams sitting in the dugout, well a Raspberry Pi that can communicate with servers should be an ideal choice or sometimes maybe a combination of the two worlds is on cards.
So, now let’s look at the question at hand. When to use Arduino and when to use Raspberry Pi?
The answer is it depends. Arduino is a housing to a microcontroller unit which is a low power, low memory control unit capable of monitoring and controlling small devices and performing repetitive tasks in an embedded system. Raspberry Pi on the other hand is a stand-alone compute unit with more processing power, persistent storage that is capable of running an operating system and is suited for more powerful multi-variate tasks that may and many not involve server-based communication.
In simple words, a microcontroller is good at communicating with devices (sensors and actuators) and a Raspberry Pi is good at communicating with a server.
Now, there can be many occasions where one trumps the other in terms of applicability and there can also be occasions where you need both of them to work in tandem.
So, it really depends on the situation you are in and the project that you have in hand.
One important insight that I learnt with my time working in automobile industry is that your development needs to be economically optimized and if possible frugal.
The fundamental fact when it comes to electronics is there are so many ways you can deploy to carry out a task.
The real question is, do you have the capacity to develop a project that does the job effectively and at the same time doesn’t cost more than it should.
So, whether you use an Arduino board or a Raspberry Pi, at the end it should answer this question rightly.
FAQs About Raspberry Pi, Arduino And Sensors
So, I hope I was able to effectively and comprehensively relay the relationship between Raspberry Pi and Arduino and how you can use the sensors you use with your Arduino projects with raspberry Pi.
Keeping the context of the post which is do Arduino sensors work with raspberry pi, I am pretty sure your queries won’t stop here.
Let me just quickly address few more queries that I am speculating you as someone interested in practical electronics will invariably have.
How Many Sensors Can Be Connected To Raspberry Pi?
Ideally you can connect as many sensors to your Raspberry Pi as there are GPIO pins which is equal to 26. However, most of the times things aren’t as black and white. It really depends on what kind of interface you are connecting your sensors to. RPi offers 4 types of interfaces viz., I2C, SPI, UART and GPIO. Each sensor will get connected to the interface it is designed for and many times sensors may demand more than one interface. The interfaces have their positives and limitations and if needed something like a GPIO extender can be used if you require more GPIO pins.
So, it all comes down to what your task at hand is.
If you are a beginner, I would recommend learning how to interface sensors to each of those interfaces one by one.
Once you are clear with the basics proficient at interfacing sensors, start expanding your knowledge base from there.
Can Raspberry Pi Do Everything Arduino Can?
For most cases yes, but not as a standalone unit. For example, microcontrollers have in-built ADC’s that you can directly interface with sensors and develop monitoring and or controlling embedded systems. To achieve the same thing with Raspberry Pi you will need a separate ADC like the MCP3008 to accomplish the same task.
The question demands a bit more subjective answer than that.
Once again in electronics the important question isn’t can it be done but how should it be done.
Because both are in essence control and compute units, in most cases you can replace one with the other but should you is a very important question you will have to ask.
It’s like the old saying, don’t use a sword when a needle gets the job done.
This should make it even more clear.
You can look at a Raspberry Pi as a stripped-down implementation of a PC and Arduino can be understood as a stripped-down version of a compute unit available in your AC or your refrigerator.
So, each of them has their own place which depends upon what task you have at hand that needs to be executed.
Can Arduino And Raspberry Pi Work Together?
Yes, a Raspberry Pi and an Arduino can be interfaced together in order to work as a unit. One obvious application that I can think of is using an Arduino to collect sensor data from the engine of a vehicle and send the data values to raspberry pi via an overhead network where it can be save on a server so that it can be accessed by engineers and operators to optimize vehicle performance.
It may seem like a complicated ordeal but once you get well versed with things like interfacing sensors and other intermediatory chips with Raspberry Pi, you will see that stepping into more complex projects like this becomes fairly intuitive and not to mention rewarding when you finally do it.
Alright, with that we are at the end of this post where we discussed how you can thin the borders between Arduino and Raspberry Pi environments.
We started with answering a simple query on do Arduino sensors work with Raspberry Pi and discussed all topics that are I felt were relevant to the context.
If you have any other doubts, queries, comments or feedbacks regarding what you learnt today, don’t hesitate to share on the comments section below.
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Take great care of yourselves and I will see you in the next one.
Tada!
