Keypad 4 Button Key Module Switch Keyboard For Arduino UNO MEGA2560 Breadboard

Description: Can be inserted directly into Arduino uno mega2560, Ideal for linking up to your Arduino UNO Mini Nano Mega2560 Breadboard etc, or others MCU ( AVR STM32 ARM PIC AT89C51 STC MSP430 STM8 FPGA CPLD etc.) 4-button Common Cathode key module GND "K1 K2 K3 K4" 4 PIN OUT 2.54mm Size: 12.7MM x 33MM. Circuit schematics: Package includes: 1 x Keyboard Arduino uno/mega2560 Code //******************************************************// /* Arduino_4key_uart This example code is in the public domain. */ // Define key pin int K1 = 13; int K2 = 12; int K3 = 11; int K4 = 10; // variables will change: int buttonState = 0; // variable for reading the pushbutton status // the setup routine runs once when you press reset: void setup() { // initialize the keys pin as an input. pinMode(K1, INPUT); pinMode(K2, INPUT); pinMode(K3, INPUT); pinMode(K4, INPUT); //Activate key pin internal pull-up resistors digitalWrite(K1, HIGH); digitalWrite(K2, HIGH); digitalWrite(K3, HIGH); digitalWrite(K4, HIGH); // initialize serial communications at 9600 bps: Serial.begin(9600); } // the loop routine runs over and over again forever: void loop() { buttonState = digitalRead(K1); if(.buttonState)Serial.print("k1 n" ); do { buttonState = digitalRead(K1); } while(.buttonState);//Wait button release buttonState = digitalRead(K2); if(.buttonState)Serial.print("k2 n" ); do { buttonState = digitalRead(K2); } while(.buttonState);//Wait button release buttonState = digitalRead(K3); if(.buttonState)Serial.print("k3 n" ); do { buttonState = digitalRead(K3); } while(.buttonState);//Wait button release buttonState = digitalRead(K4); if(.buttonState)Serial.print("k4 n" ); do { buttonState = digitalRead(K4); } while(.buttonState);//Wait button release delay(100); } //******************************************************//