Measuring voltage is quite easy using any microcontroller as compared to the measurement of current. Measuring voltages becomes necessary if you are working with batteries or you want to make your own adjustable power supply. Though this method applies to any uC but in this tutorial, we will learn how to measure voltage using Arduino. Show
There are voltage sensors available in the market. But do you really need them? Let's find out! Add TipAsk QuestionCommentDownload Step 1: Basics A microcontroller cannot understand analog voltage directly. That is why we have to use an Analog to Digital Converter or ADC in short. Atmega328 which is the brain of the Arduino Uno has 6 channel (marked as A0 to A5), 10-bit ADC. This means that it will map input voltages from 0 to 5V into integer values from 0 to (2^10-1) i.e. equal to 1023 which gives a resolution of 4.9mV per unit. 0 will correspond to 0V, 1 to 4.9mv, 2 to 9.8mV and so on till 1023. Add TipAsk QuestionCommentDownload Step 2: Measuring 0-5VFirst, we will see how to measure voltage with a maximum voltage of 5V. This is very easy as no special modifications are required. To simulate the varying voltage, we will use a potentiometer whose middle pin is connected to any one of the 6 channels. We will now write the code to read the values from ADC and convert them back into useful voltage readings. Reading the analog pin A0 value = analogRead(A0); Now, the variable 'value' contains a value between 0 to 1023 depending upon the voltage. voltage = value * 5.0/1023; The obtained value is now multiplied by the resolution (5/1023 = 4.9mV per unit) to get the actual voltage. And finally, display the measured voltage on the Serial monitor. Serial.print("Voltage = ");
Serial.println(voltage);Attachments
Add TipAsk QuestionCommentDownload Step 3: Measuring Voltage Above 5VBut the problem arises when the voltage to be measured exceeds 5 volts. This can be solved using a voltage divider circuit which consists of 2 resistors connected in series as shown. One end of this series connection is connected to the voltage to be measured (Vm) and the other end to the ground. A voltage (V1) proportional to the measured voltage will appear at the junction of two resistors. This junction can then be connected to the analog pin of the Arduino. The voltage can be found out using this formula. V1 = Vm * (R2/(R1+R2)) The voltage V1 is then measured by the Arduino. Add TipAsk QuestionCommentDownload Step 4: Building the Voltage DividerNow to build this voltage divider, we first need to find out the values of resistors. Follow these steps to calculate the value of resistors.
For example, Let the maximum voltage (Vm) to be measured be 12V and R1 = 47 kilo-ohms. Then using the formula R2 comes out to be equal to 33k. Now, Build a voltage divider circuit using these resistors. With this setup, we now have an upper and lower limit. For Vm = 12V we get V1 = 5V and for Vm = 0V we get V1 = 0V. That is, for 0 to 12V at Vm, there will be a proportional voltage from 0 to 5V at V1 which can then be fed into the Arduino as before. Add TipAsk QuestionCommentDownload Step 5: Reading the VoltageWith a slight modification in the code, we can now measure 0 to 12V. Analog value is read as before. Then, using the same formula mentioned previously, the voltage between 0 and 12V is measured. value = analogRead(A0); voltage = value * (5.0/1023) * ((R1 + R2)/R2); The commonly available Voltage Sensor Modules are nothing but just a voltage divider circuit. These are rated for 0 to 25V with 30 kiloohm and 7.5 kilo-ohm resistors. So, Why to BUY, when you can DIY! Thank you for sticking till the end. I hope that this tutorial would have helped you. Subscribe to my YouTube channel for more upcoming projects and tutorials. Thanks once again! Attachments
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22 Comments0 luketaiwan2019 Question 1 year ago AnswerUpvote I want to measure electricity below 200v, is this okay? 0 schroederM100luketaiwan2019 Answer 1 year ago ReplyUpvote Yes it will. As long as your voltage divider creates a value equal to or below 5 volts. In your case your voltage divider is (1/40) and would produce 5 volts with a 200 volt input. 0 luketaiwan2019schroederM100 Reply 3 months ago ReplyUpvote Thank you! 1 majjvb3luna3 1 year ago on ReplyUpvote Hey! Do you think this could work but with a lower voltage and sensitivity? Up to 150mV with a 0.1mV step? 0 luketaiwan2019 1 year ago ReplyUpvote Nice project! 0 on4ssc 1 year ago ReplyUpvote Hello! 0 noir97 Question 3 years ago AnswerUpvote hi, can voltage divider measure the output of pulsating dc voltage (pwm) ? in this case the voltage across 12v dc motor that it's speed was controlled by pwm. I've been tried it but the result of its measurement as i saw it from serial monitor arduino was so fluctuating, like 6v goes to 5v and then up again to 4v down again to 6v all the time. But when i measure it using multitester it shows stable 6v. Maybe some advice or solutions ? 2 answers0 Hairyloonnoir97 Answer 3 years ago ReplyUpvote Your meter is probably just taking a better average reading than the arduino, which is taking each measurement at an instant. 0 mrnegpantsHairyloon Reply 1 year ago ReplyUpvote voltage is 12 Volts. What you want to power measurement. I assumume you need to record pulse on time over a time period. 0 JohnS1343 2 years ago ReplyUpvote This solution often gets banded around, but it's a bad one. Voltage dividers constantly drain power, which for an inherently low power device like an arduino which is often battery operated, is terrible. For well powered devices, it's just inefficient. 3 replies1 yhofalcaoJohnS1343 Reply 2 years ago ReplyUpvote Could you give a good solution? (This is not to criticize your reply). I'm trying to learn exactly this. So any links would be very helpful 0 JohnS1343yhofalcao Reply 2 years ago ReplyUpvote Yes I can. The one I used as a solution for my project is an INA219. A much more elegant solution that also comes with a ammeter and is digital. If you search or scroll down on here: 1 mrnegpantsJohnS1343 Reply 1 year ago ReplyUpvote this solution also will drain power 0 Davh10 Question 2 years ago AnswerUpvote Hello, how i can protect arduino if the voltage raises up the Vm expect voltage? 0 lemansouri.med Question 2 years ago on AnswerUpvote why did you choose 47k for r1 ,is that random or it needs to be in a certan range 1 answer1 indoorgeeklemansouri.med Answer 2 years ago ReplyUpvote R1 can be of any standard value i.e. available in the market (or with you). Higher the better as less current would flow through the voltage divider. 0 kmmaran 2 years ago ReplyUpvote thanks..it worked and helped me!..there is minor accuracy issue, but hey is not hundreds of dollars of machine ..keep up the good work. Do you have any current measurement example. Which of the following laser printer components are most likely to cause a burn?First, if you open a laser printer, be careful when working around the fuser assembly because it can cause serious burns.
What would cause a laser printer to generate a totally black sheet quizlet?-No power to the primary corona would cause a totally black paper.
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Using a multimeter, what reading should you get from pin 9 on a laser printer?
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