Arduino Nano/Uno digital output not outputting 5v

Other Hardware Motors, Mechanics, Power and CNC
1

Hi! I'm very new to Arduino programming (this is my second project), so please bear with me.

I'm trying to make an automatic irrigation system, where I have a moisture sensor, and when it is below a certain amount, my Arduino powers a small 5v peristaltic pump.

The problem is that the pump is not strong enough and barely pumps water out when connected to digital pin 1-12. I know that it is being supplied with less than 3.3v, as I tried manually powering it with 5v and 3.3v (on the board), and it gives MUCH more strength than the digital output pins do.

I thought the digital output pins were supposed to give 5v, thus I assume it would properly power the pump. All of the other components are wired correctly, everything works as it should aside from the strength of the pump. I tried this with a Nano and an Uno, same results.

Would I need an external power source for my project? I assumed it'd be simple enough to do like this.

Here is the code:

int soilMoistureValue = 0;
int percentage=0;
const int outpin = 12;

void setup() {
  pinMode(outpin,OUTPUT);
  Serial.begin(9600);
}

void loop() {
soilMoistureValue = analogRead(A0);
//Serial.println(soilMoistureValue);
Serial.print("Moisture Level: ");
Serial.print(percentage);
Serial.println("%");

percentage = map(soilMoistureValue, 190, 540, 100, 0);

if(percentage < 90)  
{
  Serial.println(" pump on");
  digitalWrite(outpin,HIGH);
}

if(percentage >95)
{
  Serial.println("pump off");
  digitalWrite(outpin,LOW);
}
delay(1000);
}```
2

The digital output pins can only supply 20ma. You can damage the Arduino by trying to pull more current. You can not drive a pump motor directly from the output pins. You will need the Arduino output to switch a transistor, mosfet, or relay which connects the pump to a voltage source which can supply the current.

1 Like
3

Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advice on) your project :wink: See About the Installation & Troubleshooting category.

4

relay module....

5

Yes, you need an external power because that method works ,better you use a transisor or relay module.

6

transistor is affordable

7

relay module is used for high volts arduino cant handle

8

delay command is used for its name

9

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