Raspberry pi key board
<br />Development Board Keypad
<br />FPGA Key CPLD Key ARM Key AVR Key
<br /> 
<br />No matter how many pieces you buy the board, you only need to pay $2 shipping
<br />Module No.:  TB372
<br />
<br />Packing list:
<br />1 PCS  4-button modules
<br />
<br />Description: 
<br />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.) 
<br />1 4-button Common Cathode key module .
<br />2 " GND K1 K2 K3 K4" 4 PIN OUT  2.54mm
<br />3 Size: 12.7MM x 33MM.
<br />
<br />Arduino uno/mega2560 Code
<br /> 
<br />//******************************************************// 
<br />/*
<br />Arduino_4key_uart
<br />This example code is in the public domain.
<br />*/
<br />// Define key pin
<br />int K1 = 13;
<br />int K2 = 12;
<br />int K3 = 11;
<br />int K4 = 10;
<br />// variables will change:
<br />int buttonState = 0; // variable for reading the pushbutton status
<br />// the setup routine runs once when you press reset:
<br />void setup() {
<br />// initialize the keys pin as an input.
<br />pinMode(K1, INPUT);
<br />pinMode(K2, INPUT);
<br />pinMode(K3, INPUT);
<br />pinMode(K4, INPUT);
<br />//Activate key pin internal pull-up resistors
<br />digitalWrite(K1, HIGH);
<br />digitalWrite(K2, HIGH);
<br />digitalWrite(K3, HIGH);
<br />digitalWrite(K4, HIGH);
<br />// initialize serial communications at 9600 bps:
<br />Serial.begin(9600);
<br />}
<br />// the loop routine runs over and over again forever:
<br />void loop() {
<br />buttonState = digitalRead(K1);
<br />if(!buttonState)Serial.print("k1 
<br />" );
<br />do
<br />{
<br />buttonState = digitalRead(K1);
<br />}
<br />while(!buttonState);//Wait button release
<br />buttonState = digitalRead(K2);
<br />if(!buttonState)Serial.print("k2 
<br />" );
<br />do
<br />{
<br />buttonState = digitalRead(K2);
<br />}
<br />while(!buttonState);//Wait button release
<br />buttonState = digitalRead(K3);
<br />if(!buttonState)Serial.print("k3 
<br />" );
<br />do
<br />{
<br />buttonState = digitalRead(K3);
<br />}
<br />while(!buttonState);//Wait button release
<br />buttonState = digitalRead(K4);
<br />if(!buttonState)Serial.print("k4 
<br />" );
<br />do
<br />{
<br />buttonState = digitalRead(K4);
<br />}
<br />while(!buttonState);//Wait button release
<br />delay(100);
<br />}
<br />    
<br /> //******************************************************//
<br />
<br /> 
<br /> Introduction for Shenzhen Canton-electronics Trading Co.,Ltd :
<br />We specialize in RF Wireless Radio Transmitting Units and Receiving Units, the product include transmitters with case, receivers with relay(s), transmittng modules and receiving modules, are widely applied in RC toy, remote sensing, telemetry, fireworks, industrial control, home&garden application.
<br />
<br /> 
<br /> Shipping:
<br />Normally shipping is by Airmail from China Post Air Mail or Hong Kong Post Air Mail ,15-60 days shipping time based on different country .
<br />Express is available, shipping time is 2-7 days all over the world, and telephone number is needed. Please contact us first for extra payment .
<br /> 
<br /> Benefits
<br />The Best Prices. By working with Canton-electronics Ltd, you can take advantage of the internet business, cut off the wholesalers cost and other costs, and import your products directly from the manufacturer at incredible prices.
<br />Prompt Delivery. Most units are in stock all the time, standard units will be completed within 1-3 days if they are sold out, it is great help for you if your project must be completed before deadline.
<br />Prompt Service. Mails will be replied within 24 hours We work 6 days  a week.
<br /> 
<br /> Return Policy
<br />All mails will be replied to within 24 hours except on weekend and holidays.
<br />Every item is manufactured under Strict Quality-Assurance Guidelines. If you are dissatisfied for any reason, please return the product to us, and we'll refund your money(not  including  shipping fees).
<br />Please ensure that return items are not used.
<br />Return items must be Posted within 7 days of receipt.
<br />Please inform us via email before posting your return package.
<br /> 
<br /> Import tax : 
<br /> We will dispatch the item as SAMPLE or GIFT,  label the total amount on the custom declare invoice .
<br /> Import duties, taxes and charges are not included in the item price or shipping charges. These charges are the buyer s responsibility. Please check with your country s customs office to determine what these additional costs will <p> <b><b><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-large.jpg"><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-1-large.jpg"><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-2-large.jpg" noproxy><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-3-large.jpg"><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-4-large.jpg"><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-5-large.jpg"><img src="https://contestimg.wish.com/api/webimage/573447a1ad11fb5d150e27cf-6-large.jpg></b></b></p>