Hi,
I am building a low power application and want to switch a sensor or two off before I put an Arduino to sleep and switch the sensor back on after the Arduino has woken up.
I read that it is possible using for example a logic level MOSFET such as IRL520N, and thought to give it a try.
My sensor that I want to control is a Sonar Sensor
I built a circuit to test with using an Arduino Nano for example, and using the 5V as the source for the sensor.
The issue I am experiencing is that the sensors voltage between 5V and GND never drops to Zero. I can see the sensor voltage dropping between the times I apply voltage to the GATE but it never drops below +- 3.7V even if I remove the GND connector between DRAIN and the Sensors GND.
If I remove the TX and RX connections then the voltage drops to 0.9V which is similar to the voltage between GATE and DRAIN if the voltage to the GATE is removed.
I obviously have some feedback going on in this circuit and would like some advice. Can I maybe solve this by strategically placing diodes and resistors in some places?
Am I running up the wrong tree using MOSFETS?
My test circuit looks like the first attachment: CircuitTEST.jpg
While my final design will look something like the second attachment: Circuit.jpg
Code I am using:
#include <SoftwareSerial.h>
#define ECHOPIN 12// Pin to receive echo pulse
#define TRIGPIN 11// Pin to send trigger pulse
#define GATE 5
void setup() {
Serial.begin(9600);
pinMode(ECHOPIN, INPUT);
pinMode(TRIGPIN, OUTPUT);
digitalWrite(ECHOPIN, HIGH);
pinMode(GATE, OUTPUT);
digitalWrite(GATE, LOW);
}
int getDistance() {
digitalWrite(GATE, HIGH);
digitalWrite(ECHOPIN, HIGH);
delay(3000);
digitalWrite(TRIGPIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIGPIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIGPIN, LOW);
int distance = pulseIn(ECHOPIN, HIGH,26000);
distance= distance/58;
Serial.print("distance: ");
Serial.println(distance);
digitalWrite(ECHOPIN, LOW);
digitalWrite(GATE, LOW);
delay(6000);
return distance;
}
void loop() {
int distance = getDistance();
}
I know the circuit works because I tested with an LED and it works fine, but this sensor has its own breakout board and additional connections to other Arduino digital pins which makes it a bit more complicated.
