/elec/quadcopter

To get this branch, use:
bzr branch http://bzr.ed.am/elec/quadcopter

« back to all changes in this revision

Viewing changes to test/receiver/pulse-width/main.ino

  • Committer: Tim Marston
  • Date: 2012-11-28 23:18:38 UTC
  • Revision ID: tim@ed.am-20121128231838-r2t1dyawkzb6nxhe
initial commit, and a couple of receiver test programs

Show diffs side-by-side

added added

removed removed

Lines of Context:
 
1
//
 
2
// main.ino
 
3
//
 
4
// Testing reading from the receiver.  We're expecting a PWM signal, on
 
5
// interrupt 0 (which is pin 2 on an Arduino Uno).
 
6
//
 
7
// This program tries to measure the width of the signal pulses in
 
8
// microseconds.  It takes several measurements and prints it the average over
 
9
// serial.
 
10
//
 
11
 
 
12
 
 
13
// number of signal pulses to average
 
14
#define SIGNAL_SAMPLES 10
 
15
 
 
16
 
 
17
// set to the time that the last signal pulse was at
 
18
static unsigned long _new_pulse_on = 0;
 
19
static unsigned long _new_pulse_off = 0;
 
20
 
 
21
 
 
22
// ISR to handle the PWM signal
 
23
void signal_handler()
 
24
{
 
25
        // record time
 
26
        if( digitalRead( 2 ) )
 
27
                _new_pulse_on = micros();
 
28
        else
 
29
                _new_pulse_off = micros();
 
30
}
 
31
 
 
32
 
 
33
void setup()
 
34
{
 
35
        // set up an interrupt handler on pin 2
 
36
        attachInterrupt( 0, signal_handler, CHANGE );
 
37
        digitalWrite( 2, LOW );
 
38
 
 
39
        Serial.begin( 9600 );
 
40
}
 
41
 
 
42
void loop()
 
43
{
 
44
        unsigned long last_pulse = 0;
 
45
        unsigned long intervals[ SIGNAL_SAMPLES ] = {0};
 
46
        int interval_idx = 0;
 
47
 
 
48
        while( true )
 
49
        {
 
50
                // detect pulse falling-edge
 
51
                unsigned long new_pulse_on = _new_pulse_on;
 
52
                unsigned long new_pulse_off = _new_pulse_off;
 
53
                bool got_pulse = false;
 
54
                if( new_pulse_off > last_pulse )
 
55
                {
 
56
                        // update interval buffer
 
57
                        intervals[ interval_idx ] = new_pulse_off - new_pulse_on;
 
58
                        if( ++interval_idx >= SIGNAL_SAMPLES )
 
59
                                interval_idx = 0;
 
60
 
 
61
                        last_pulse = new_pulse_off;
 
62
                        got_pulse = true;
 
63
                }
 
64
 
 
65
                // display average?
 
66
                if( interval_idx == 0 && got_pulse )
 
67
                {
 
68
                        // calculate average
 
69
                        double ave = 0;
 
70
                        for( int a = 0; a < SIGNAL_SAMPLES; a++ )
 
71
                                ave += intervals[ a ];
 
72
                        ave /= SIGNAL_SAMPLES;
 
73
 
 
74
                        // tell it like it is
 
75
                        Serial.println( round( ave ) );
 
76
                }               
 
77
        }
 
78
}