Baser Kandehir / Mbed 2 deprecated timer_interrupts Featured

This is an example program that shows how to use timer, ticker and interrupts. It uses LPC1768 board leds and a button to show how interrupts, timers and tickers are implemented to toggle leds.

Dependencies:   mbed

main.cpp@1:f4088d23f670, 2015-07-21 (annotated)

Committer:
BaserK
Date:
Tue Jul 21 08:22:46 2015 +0000
Revision:
1:f4088d23f670
Parent:
0:fe71c302ccbb 
MIT license is added

Who changed what in which revision?

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BaserK 0:fe71c302ccbb 1 /* Interrupt, timer and ticker example on LPC1768
BaserK 0:fe71c302ccbb 2 *
BaserK 0:fe71c302ccbb 3 * @author: Baser Kandehir
BaserK 0:fe71c302ccbb 4 * @date: July 9, 2015
BaserK 1:f4088d23f670 5 * @license: MIT license
BaserK 1:f4088d23f670 6 *
BaserK 1:f4088d23f670 7 * Copyright (c) 2015, Baser Kandehir, baser.kandehir@ieee.metu.edu.tr
BaserK 1:f4088d23f670 8 *
BaserK 1:f4088d23f670 9 * Permission is hereby granted, free of charge, to any person obtaining a copy
BaserK 1:f4088d23f670 10 * of this software and associated documentation files (the "Software"), to deal
BaserK 1:f4088d23f670 11 * in the Software without restriction, including without limitation the rights
BaserK 1:f4088d23f670 12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
BaserK 1:f4088d23f670 13 * copies of the Software, and to permit persons to whom the Software is
BaserK 1:f4088d23f670 14 * furnished to do so, subject to the following conditions:
BaserK 1:f4088d23f670 15 *
BaserK 1:f4088d23f670 16 * The above copyright notice and this permission notice shall be included in
BaserK 1:f4088d23f670 17 * all copies or substantial portions of the Software.
BaserK 1:f4088d23f670 18 *
BaserK 1:f4088d23f670 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
BaserK 1:f4088d23f670 20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
BaserK 1:f4088d23f670 21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
BaserK 1:f4088d23f670 22 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
BaserK 1:f4088d23f670 23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
BaserK 1:f4088d23f670 24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
BaserK 1:f4088d23f670 25 * THE SOFTWARE.
BaserK 1:f4088d23f670 26 *
BaserK 0:fe71c302ccbb 27 * @description of the program:
BaserK 0:fe71c302ccbb 28 *
BaserK 0:fe71c302ccbb 29 * This is an example program that shows how to use timer, ticker and interrupts.
BaserK 0:fe71c302ccbb 30 * It uses LPC1768 board leds and a button to show how interrupts, timers and tickers
BaserK 0:fe71c302ccbb 31 * are implemented to toggle leds.
BaserK 0:fe71c302ccbb 32 * A ticker is an interrupt service routine which calls a function at periodic time intervals.
BaserK 0:fe71c302ccbb 33 * There are two tickers in the program. First ticker calls the toggle_led1 function every 100 ms
BaserK 0:fe71c302ccbb 34 * and second ticker calls the toggle_led2 function every 500 ms. A button is connected to show
BaserK 0:fe71c302ccbb 35 * how external interrupts work on the mbed LPC1768. Whenever user pushes the button, it pulls
BaserK 0:fe71c302ccbb 36 * down the pin 18 to 0V and external interrupt occurs at the falling edge of p18. Whenever an external
BaserK 0:fe71c302ccbb 37 * interrupt occurs, it calls the led3_debounced function to toggle led3. Also a timer is used to debounce
BaserK 0:fe71c302ccbb 38 * the button by counting 20 ms. Debounce is required for buttons in order to prevent false readings.
BaserK 0:fe71c302ccbb 39 *
BaserK 0:fe71c302ccbb 40 * @connections: Pull up button with 10k resistor is connected to pin 18.
BaserK 0:fe71c302ccbb 41 *
BaserK 0:fe71c302ccbb 42 */
BaserK 0:fe71c302ccbb 43
BaserK 0:fe71c302ccbb 44 #include "mbed.h"
BaserK 0:fe71c302ccbb 45
BaserK 0:fe71c302ccbb 46 Ticker toggler1; // periodic interrupt routines
BaserK 0:fe71c302ccbb 47 Ticker toggler2;
BaserK 0:fe71c302ccbb 48 Timer debounce; // define debounce timer
BaserK 0:fe71c302ccbb 49 InterruptIn button(p18); // hardware interrupt on button - pin 18
BaserK 0:fe71c302ccbb 50
BaserK 0:fe71c302ccbb 51 /* IMPORTANT NOTE: any digital input can be an interrupt except pin 19 and pin 20 */
BaserK 0:fe71c302ccbb 52
BaserK 0:fe71c302ccbb 53 /* Interesting way of initialize all the 4 leds on the LPC1768 to an array named leds[]. */
BaserK 0:fe71c302ccbb 54 DigitalOut leds[] = {(LED1), (LED2), (LED3), (LED4)};
BaserK 0:fe71c302ccbb 55
BaserK 0:fe71c302ccbb 56 /* Function Prototypes */
BaserK 0:fe71c302ccbb 57 void toggle_led1();
BaserK 0:fe71c302ccbb 58 void toggle_led2();
BaserK 0:fe71c302ccbb 59 void led3_debounced();
BaserK 0:fe71c302ccbb 60
BaserK 0:fe71c302ccbb 61 int main()
BaserK 0:fe71c302ccbb 62 {
BaserK 0:fe71c302ccbb 63 /* Leds are initially OFF */
BaserK 0:fe71c302ccbb 64 for(int i=0; i<4 ;i++)
BaserK 0:fe71c302ccbb 65 leds[i]=0;
BaserK 0:fe71c302ccbb 66
BaserK 0:fe71c302ccbb 67 /* Start debounce timer */
BaserK 0:fe71c302ccbb 68 debounce.start();
BaserK 0:fe71c302ccbb 69
BaserK 0:fe71c302ccbb 70 /* Attach functions to periodic interrupts */
BaserK 0:fe71c302ccbb 71 toggler1.attach(&toggle_led1,0.1); // toggles led1 every 100 ms
BaserK 0:fe71c302ccbb 72 toggler2.attach(&toggle_led2,0.5); // toggles led2 every 500 ms
BaserK 0:fe71c302ccbb 73
BaserK 0:fe71c302ccbb 74 /* Call toggle_led3 falling edge of the button interrupt */
BaserK 0:fe71c302ccbb 75 button.fall(&led3_debounced);
BaserK 0:fe71c302ccbb 76 while(1)
BaserK 0:fe71c302ccbb 77 {
BaserK 0:fe71c302ccbb 78
BaserK 0:fe71c302ccbb 79 }
BaserK 0:fe71c302ccbb 80 }
BaserK 0:fe71c302ccbb 81
BaserK 0:fe71c302ccbb 82 void toggle_led1() {leds[0] = !leds[0];}
BaserK 0:fe71c302ccbb 83 void toggle_led2() {leds[1] = !leds[1];}
BaserK 0:fe71c302ccbb 84
BaserK 0:fe71c302ccbb 85 // whenever user pushes the button, led3 toggles.
BaserK 0:fe71c302ccbb 86 // button is debounced by waiting at least 20 ms.
BaserK 0:fe71c302ccbb 87 void led3_debounced()
BaserK 0:fe71c302ccbb 88 {
BaserK 0:fe71c302ccbb 89 if(debounce.read_ms()>20) // only allow toggle after 20 ms
BaserK 0:fe71c302ccbb 90 {
BaserK 0:fe71c302ccbb 91 leds[2] = !leds[2];
BaserK 0:fe71c302ccbb 92 debounce.reset(); // restart timer after toggle
BaserK 0:fe71c302ccbb 93 }
BaserK 0:fe71c302ccbb 94 }