Freenove Ultimate Starter Kit User Manual

Chapter 2 Button & LED
66
www.freenove.com █
█ support@freenove.com
Code
In the project, we still detect the state of Button to control LED. Here we need to define a variable to save the
state of LED. And when the button is pressed once, the state of LED will be changed once. This has achieved
the function of the table lamp.
C Code 2.2.1 Tablelamp
First observe the project result, and then analyze the code.
1. Use cd command to enter 02.2.1_Tablelamp directory of C code.
cd ~/Freenove_Ultimate_Starter_Kit_for_Raspberry_Pi/Code/C_Code/02.1.1_Tablelamp
2. Use following command to compile “Tablelamp.c” and generate executable file “Tablelamp”.
gcc Tablelamp.c -o Tablelamp -lwiringPi
3. Tablelamp. Then run the generated file “Tablelamp”.
sudo ./Tablelamp
When the program is executed, press the Button once, then LED is turned on. Press the Button another time,
then LED is turned off.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
#include <wiringPi.h>
#include <stdio.h>
#define ledPin 0 //define the ledPin
#define buttonPin 1 //define the buttonPin
int ledState=LOW; //store the State of led
int buttonState=HIGH; //store the State of button
int lastbuttonState=HIGH;//store the lastState of button
long lastChangeTime; //store the change time of button state
long captureTime=50; //set the button state stable time
int reading;
int main(void)
{
if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
printf("setup wiringPi failed !");
return 1;
}
printf("Program is starting...\n");
pinMode(ledPin, OUTPUT);
pinMode(buttonPin, INPUT);
pullUpDnControl(buttonPin, PUD_UP); //pull up to high level
while(1){
reading = digitalRead(buttonPin); //read the current state of button
if( reading != lastbuttonState){ //if the button state has changed ,record the
time point
lastChangeTime = millis();
}

Freenove Ultimate Starter Kit Specifications

General

Brand	Freenove
Model	Ultimate Starter Kit
Category	Single board computers
Language	English