Hendrik Lipka / Mbed 2 deprecated PWMTest

Test the PWM functionality in conjunction with an analog input - drive the brightness of a LCD backlight with the ambient light level. Serves as testcase of a PWM problem, see code comment.

Dependencies:   mbed

main.cpp@0:708a1d284406, 2011-01-19 (annotated)

Committer:
hlipka
Date:
Wed Jan 19 19:46:05 2011 +0000
Revision:
0:708a1d284406
initial test version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hlipka 0:708a1d284406 1 #include "mbed.h"
hlipka 0:708a1d284406 2
hlipka 0:708a1d284406 3 #include "math.h"
hlipka 0:708a1d284406 4
hlipka 0:708a1d284406 5 /*
hlipka 0:708a1d284406 6 read the light value from a photo transistor connected to P20 and
hlipka 0:708a1d284406 7 drive a LCDs LED backlight connected to P25.
hlipka 0:708a1d284406 8 The backlight should dimm in the dark and brighten up when the lights go on.
hlipka 0:708a1d284406 9
hlipka 0:708a1d284406 10 NOTE: the version below doesn't work, remove the printf in line 35!
hlipka 0:708a1d284406 11 */
hlipka 0:708a1d284406 12 int main() {
hlipka 0:708a1d284406 13 DigitalOut led1(LED1);
hlipka 0:708a1d284406 14 float f=0.0;
hlipka 0:708a1d284406 15 PwmOut display(p25);
hlipka 0:708a1d284406 16 display.period_ms(1);
hlipka 0:708a1d284406 17 display=f;
hlipka 0:708a1d284406 18
hlipka 0:708a1d284406 19 AnalogIn light(p20);
hlipka 0:708a1d284406 20
hlipka 0:708a1d284406 21 for (int i=0;i<100;i++)
hlipka 0:708a1d284406 22 {
hlipka 0:708a1d284406 23 f=f+0.01;
hlipka 0:708a1d284406 24 display=f;
hlipka 0:708a1d284406 25 wait (0.03);
hlipka 0:708a1d284406 26 }
hlipka 0:708a1d284406 27 printf("%f\n",display.read());
hlipka 0:708a1d284406 28 led1=1;
hlipka 0:708a1d284406 29
hlipka 0:708a1d284406 30 while (true)
hlipka 0:708a1d284406 31 {
hlipka 0:708a1d284406 32 double d=light;
hlipka 0:708a1d284406 33 double sq=pow(d,0.6);
hlipka 0:708a1d284406 34 display.write(sq*3);
hlipka 0:708a1d284406 35 printf("%f / %f\n",d,sq);
hlipka 0:708a1d284406 36 wait(1);
hlipka 0:708a1d284406 37 }
hlipka 0:708a1d284406 38 }