ESP32 KY-004 Key Switch Module
Overview
The KY-004 is a key switch module equipped with a tactile push-button. It provides a digital output signal when pressed, making it ideal for user input applications in various electronic projects.
About KY-004 Key Switch Module
The KY-004 is a simple push-button switch module that provides digital input for microcontrollers. When pressed, it connects the signal pin to ground, sending a LOW signal to trigger an event. It operates within 3.3V to 5V, making it compatible with ESP32, Arduino, and other microcontrollers.
⚡ Key Features
- Push-Button Activation – Sends a LOW signal when pressed.
- Operating Voltage – Works with 3.3V to 5V, ensuring broad compatibility.
- Simple Digital Output – Easy integration with ESP32, Arduino, and similar boards.
- Versatile Applications – Used for reset functions, menu navigation, and input controls.
With its compact design and easy-to-use interface, the KY-004 is perfect for user input, interactive devices, and control applications. 🚀
Where to Buy
Starting from
1$ per unit
Prices are subject to change. We earn from qualifying purchases as an Amazon Associate.
Technical Specifications
Pinout Configuration
The VCC pin is used to supply power to the sensor, and it typically requires 3.3V or 5V (refer to the datasheet for specific voltage requirements). The GND pin is the ground connection and must be connected to the ground of your ESP32.
Pin (-):Connects to Ground (GND).Pin (+):Connects to VCC (3.3V or 5V).Pin (S):Outputs a digital signal when the button is pressed.
Wiring with ESP32
KY-004 Pin (-):Connect to ESP32GND.KY-004 Pin (+):Connect to ESP323.3Vor5V.KY-004 Pin (S):Connect to a GPIO pin on ESP32 (e.g.,GPIO4).
Troubleshooting Guide
Common Issues
❌ No Response from KY-004 Module
Issue: Pressing the button does not produce any response.
Solutions:
- Ensure all connections are secure and correctly placed.
- Verify that the module is receiving the appropriate voltage (3.3V or 5V).
- Check the microcontroller's GPIO pin configuration in the code.
- Test the module with a multimeter to confirm functionality.
⚠️ False Triggering of Button Press
Issue: The module sends signals without the button being pressed.
Solutions:
- Ensure that the pull-up resistor is properly connected and functioning.
- Implement software debouncing to filter out spurious signals.
- Check for any short circuits or loose connections on the module.
Debugging Tips
🔍 Serial Monitor
Use the Serial Monitor to check for error messages and verify the sensor's output. Add debug prints in your code to track the sensor's state.
⚡ Voltage Checks
Use a multimeter to verify voltage levels and check for continuity in your connections. Ensure the power supply is stable and within the sensor's requirements.
Additional Resources
Code Examples
Arduino Example
#define BUTTON_PIN 7
#define LED_PIN 13
void setup() {
pinMode(BUTTON_PIN, INPUT);
digitalWrite(BUTTON_PIN, HIGH); // Enable internal pull-up resistor
pinMode(LED_PIN, OUTPUT);
Serial.begin(9600);
Serial.println("KY-004 Key Switch Module Test");
}
void loop() {
int buttonState = digitalRead(BUTTON_PIN);
if (buttonState == LOW) {
Serial.println("Button pressed");
digitalWrite(LED_PIN, HIGH);
} else {
Serial.println("Button released");
digitalWrite(LED_PIN, LOW);
}
delay(100);
}This Arduino code sets up the KY-004 Key Switch Module on pin 7 and an LED on pin 13. When the button is pressed, the sensor outputs a LOW signal, turning on the LED and printing a message to the serial monitor.
ESP-IDF Example
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#define BUTTON_PIN GPIO_NUM_4
#define LED_PIN GPIO_NUM_2
void app_main(void) {
gpio_set_direction(BUTTON_PIN, GPIO_MODE_INPUT);
gpio_set_pull_mode(BUTTON_PIN, GPIO_PULLUP_ONLY);
gpio_set_direction(LED_PIN, GPIO_MODE_OUTPUT);
printf("KY-004 Key Switch Module Test\n");
while (1) {
int button_state = gpio_get_level(BUTTON_PIN);
if (button_state == 0) {
printf("Button pressed\n");
gpio_set_level(LED_PIN, 1);
} else {
printf("Button released\n");
gpio_set_level(LED_PIN, 0);
}
vTaskDelay(pdMS_TO_TICKS(100));
}
}This ESP-IDF code configures GPIO4 as an input for the KY-004 Key Switch Module and GPIO2 as an output for an LED. When the button is pressed (sensor outputs LOW), the LED turns on, and a message is printed to the console.
ESPHome Example
binary_sensor:
- platform: gpio
pin:
number: GPIO4
mode: INPUT_PULLUP
name: "KY-004 Key Switch"
filters:
- delayed_on: 10ms
- delayed_off: 10ms
on_press:
- then:
- lambda: |-
ESP_LOGD("sensor", "Button pressed!");This ESPHome configuration sets up the KY-004 Key Switch as a binary sensor on GPIO4 with an internal pull-up resistor. It includes filtering to debounce false triggers and logs when the button is pressed.
PlatformIO Example
platformio.ini
[env:esp32]
platform = espressif32
board = esp32dev
framework = arduinoPlatformIO Example Code
#include <Arduino.h>
#define BUTTON_PIN 4
#define LED_PIN 2
void setup() {
pinMode(BUTTON_PIN, INPUT_PULLUP);
pinMode(LED_PIN, OUTPUT);
Serial.begin(115200);
Serial.println("KY-004 Key Switch Module Test");
}
void loop() {
if (digitalRead(BUTTON_PIN) == LOW) {
Serial.println("Button pressed");
digitalWrite(LED_PIN, HIGH);
} else {
Serial.println("Button released");
digitalWrite(LED_PIN, LOW);
}
delay(100);
}This PlatformIO code configures the KY-004 Key Switch on GPIO4 and an LED on GPIO2. When the button is pressed, the LED turns on, and a message is printed to the serial monitor.
MicroPython Example
import machine
import time
BUTTON_PIN = machine.Pin(4, machine.Pin.IN, machine.Pin.PULL_UP)
LED_PIN = machine.Pin(2, machine.Pin.OUT)
while True:
if BUTTON_PIN.value() == 0:
print("Button pressed")
LED_PIN.on()
else:
print("Button released")
LED_PIN.off()
time.sleep(0.1)This MicroPython script configures the KY-004 Key Switch on GPIO4 and an LED on GPIO2. When the button is pressed (LOW signal), the LED turns on, and a message is printed to the console.
Conclusion
The ESP32 KY-004 Key Switch Module is a powerful KY-0xx module sensor that offers excellent performance and reliability. With support for multiple development platforms including Arduino, ESP-IDF, ESPHome, PlatformIO, and MicroPython, it's a versatile choice for your IoT projects.
For optimal performance, ensure proper wiring and follow the recommended configuration for your chosen development platform.
Always verify power supply requirements and pin connections before powering up your project to avoid potential damage.
