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Arduino - Touch Sensor - Solenoid Lock
We are going to learn how to use Arduino to control the solenoid lock in two use cases:
- Arduino turns on the solenoid lock if the touch sensor is touched and turns off the solenoid lock if the touch sensor is NOT touched.
- Arduino toggles the solenoid lock each time touch sensor is touched.
Hardware Required
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.
About Touch Sensor and Solenoid Lock
If you do not know about solenoid lock and touch sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Arduino Code - Touch Sensor controls Solenoid Lock
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-touch-sensor-solenoid-lock
*/
const int TOUCH_SENSOR_PIN = 8; // Arduino pin connected to touch sensor's pin
const int RELAY_PIN = A5; // Arduino pin connected to the solenoid lock via relay
void setup() {
Serial.begin(9600); // initialize serial
pinMode(TOUCH_SENSOR_PIN, INPUT); // set arduino pin to input mode
pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode
}
void loop() {
int touchState = digitalRead(TOUCH_SENSOR_PIN); // read new state
if (touchState == HIGH) {
Serial.println("The sensor is being touched");
digitalWrite(RELAY_PIN, HIGH); // turn on
}
else
if (touchState == LOW) {
Serial.println("The sensor is untouched");
digitalWrite(RELAY_PIN, LOW); // turn off
}
}
Quick Steps
- Connect Arduino to PC via USB cable
- Open Arduino IDE, select the right board and port
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Touch and keep touching the touch sensor several seconds
- See the change of solenoid lock's state
Code Explanation
Read the line-by-line explanation in comment lines of source code!
Arduino Code - Touch Sensor Toggles Solenoid Lock
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-touch-sensor-solenoid-lock
*/
const int TOUCH_SENSOR_PIN = 8; // Arduino pin connected to touch sensor's pin
const int RELAY_PIN = A5; // Arduino pin connected to solenoid lock via relay
// variables will change:
int solenoidLockState = LOW; // the current state of relay
int lastTouchState; // the previous state of touch sensor
int currentTouchState; // the current state of touch sensor
void setup() {
Serial.begin(9600); // initialize serial
pinMode(TOUCH_SENSOR_PIN, INPUT); // set arduino pin to input mode
pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode
currentTouchState = digitalRead(TOUCH_SENSOR_PIN);
}
void loop() {
lastTouchState = currentTouchState; // save the last state
currentTouchState = digitalRead(TOUCH_SENSOR_PIN); // read new state
if(lastTouchState == LOW && currentTouchState == HIGH) {
Serial.println("The sensor is touched");
// toggle state of relay
solenoidLockState = !solenoidLockState;
// control relay arccoding to the toggled state
digitalWrite(RELAY_PIN, solenoidLockState);
}
}
Quick Steps
- Connect Arduino to PC via USB cable
- Open Arduino IDE, select the right board and port
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Keep touching the touch sensor several seconds and then release it.
- See the change of solenoid lock's state
Code Explanation
Read the line-by-line explanation in comment lines of code!
In the code, solenoidLockState = !solenoidLockState is equivalent to the following code:
if(solenoidLockState == LOW)
solenoidLockState = HIGH;
else
solenoidLockState = LOW;
Video Tutorial
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