Andy K / Ton

A Ton (Timer On) is used to provide an \'on delay\' system so as to avoid using wait()

Dependents:   NEWlcd_menu_v2 Garage_Control

example1.h@3:123a1b30970a, 2011-03-04 (annotated)

Committer:
AjK
Date:
Fri Mar 04 14:15:47 2011 +0000
Revision:
3:123a1b30970a
Parent:
0:748acff4e3c8 
1.3 See ChangeLog.h

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AjK 0:748acff4e3c8 1 /*
AjK 0:748acff4e3c8 2 * This example DOES NOT use a Ton timer. It shows how
AjK 0:748acff4e3c8 3 * beginners often "abuse" wait() to wait for a period
AjK 0:748acff4e3c8 4 * of time before actioning something. As shown here we
AjK 0:748acff4e3c8 5 * delay the switching on an LED after an input is asserted.
AjK 0:748acff4e3c8 6 *
AjK 0:748acff4e3c8 7 * The problem is that they "interfer" with each other. Using
AjK 0:748acff4e3c8 8 * wait() to wait around causes the entire system to hold up
AjK 0:748acff4e3c8 9 * waiting some period of time. As you can see, this holds up
AjK 0:748acff4e3c8 10 * the main() systems while(1) loop preventing any other task
AjK 0:748acff4e3c8 11 * or process from being performed.
AjK 0:748acff4e3c8 12 *
AjK 0:748acff4e3c8 13 * THIS IS AN EXAMPLE OF HOW NOT TO DO IT!
AjK 0:748acff4e3c8 14 *
AjK 0:748acff4e3c8 15 * To see how the Ton object can fix this issue see example2.h
AjK 0:748acff4e3c8 16 */
AjK 0:748acff4e3c8 17 #include "mbed.h"
AjK 0:748acff4e3c8 18
AjK 0:748acff4e3c8 19 DigitalIn ip1(p19);
AjK 0:748acff4e3c8 20 DigitalIn ip2(p20);
AjK 0:748acff4e3c8 21
AjK 0:748acff4e3c8 22 DigitalOut led1(LED1);
AjK 0:748acff4e3c8 23 DigitalOut led2(LED2);
AjK 0:748acff4e3c8 24
AjK 0:748acff4e3c8 25 void f1(void) {
AjK 0:748acff4e3c8 26 if (ip1) {
AjK 0:748acff4e3c8 27 wait(2);
AjK 0:748acff4e3c8 28 led1 = 1;
AjK 0:748acff4e3c8 29 }
AjK 0:748acff4e3c8 30 else {
AjK 0:748acff4e3c8 31 led1 = 0;
AjK 0:748acff4e3c8 32 }
AjK 0:748acff4e3c8 33 }
AjK 0:748acff4e3c8 34
AjK 0:748acff4e3c8 35 void f2(void) {
AjK 0:748acff4e3c8 36 if (ip2) {
AjK 0:748acff4e3c8 37 wait(2);
AjK 0:748acff4e3c8 38 led2 = 1;
AjK 0:748acff4e3c8 39 }
AjK 0:748acff4e3c8 40 else {
AjK 0:748acff4e3c8 41 led2 = 0;
AjK 0:748acff4e3c8 42 }
AjK 0:748acff4e3c8 43 }
AjK 0:748acff4e3c8 44
AjK 0:748acff4e3c8 45 int main() {
AjK 0:748acff4e3c8 46 while(1) {
AjK 0:748acff4e3c8 47 f1(); // Do process f1()
AjK 0:748acff4e3c8 48 f2(); // Do process f2()
AjK 0:748acff4e3c8 49 }
AjK 0:748acff4e3c8 50 }