Very cool, thanks for sharing your code with us! By the way, have you tried out the Pololu AVR library yet? It represents our most up-to-date code for the Orangutan robot controllers (the code you are using in devices.h and LCD.h predates the library and has since been included in the library). It also contains code for reading arbitrary pulses on arbitrary pins using pin-change interrupts and timer 1. It’s not documented quite yet, but I made a post about using it here:
Using the timer capture is an elegant way to read the pulses from a single channel of your receiver, but it can’t really be extended well to simultaneously reading multiple channels. The following example program will be included with the next release of the library, which should hopefully be available by the end of this week or early next week:
#include <pololu/orangutan.h>
/*
* pulsein1: for the 3pi robot, Orangutan LV 168, Orangutan SV-xx8, Orangutan SVP,
* or Orangutan X2
*
* This program uses the OrangutanPulseIn functions to control measure hobby servo
* pulses connected to pin D0. It also generates hobby servo pulses on pin D1,
* so if you do not have a external pulse source (such as an RC receiver or a
* servo controller), you can use a wire to connect D1 to D0 and see the PulseIn
* library measure the pulses put out by D1 and display the high and low durations
* on the LCD.
*
* https://www.pololu.com/docs/0J20
* https://www.pololu.com
* https://forum.pololu.com
*/
// This array of pins is used to initialize the PulseIn routines. To measure
// pulses on multiple pins, add more elements to the array. For example:
// const unsigned char pulseInPins[] = { IO_D0, IO_C0, IO_C1 };
const unsigned char pulseInPins[] = { IO_D0 };
int main()
{
unsigned long time_ms = get_ms();
unsigned int high_pulse_us = 1000;
char upcounting = 1;
set_digital_output(IO_D1, LOW);
clear(); // clear LCD
// using the parameter MAX_PULSE_26MS means we can only measure pulses
// up to 26 ms long, but gives 0.4 us resolution. This is a good setting
// for hobby servo pulses, which are usually 50 Hz signals (20 ms period).
// Other options are MAX_PULSE_3MS, _200MS, _800MS, and _3000MS.
pulse_in_init(pulseInPins, 1, MAX_PULSE_26MS);
while (1) // main loop
{
pulse_in_update(); // this must be called at least once every 26 ms
// when using MAX_PULSE_26MS
struct PulseInputStruct pi = get_pulse_info(0); // get pulse info for D0
if (pi.curPulseWidth == MAX_PULSE)
{
// input line has been in the same state for longer than we can time
// (e.g. it is held high or low)
if (pi.inputState == HIGH)
{
lcd_goto_xy(0, 0); // go to start of first LCD row
print("D0: HIGH");
lcd_goto_xy(0, 1); // go to start of second LCD row
print(" "); // clear the row by overwriting with spaces
}
else
{
lcd_goto_xy(0, 0); // go to start of first LCD row
print(" "); // clear the row by overwriting with spaces
lcd_goto_xy(0, 1); // go to start of second LCD row
print("D0: LOW");
}
}
else if (pi.newPulse == HIGH_PULSE)
{
lcd_goto_xy(0, 0); // go to start of first LCD row
// print the length (in us) of the most recently received high pulse
if (pi.lastHighPulse != MAX_PULSE)
print_unsigned_long(pulse_to_microseconds(pi.lastHighPulse));
print(" us ");
lcd_goto_xy(0, 1); // go to start of second LCD row
// print the length (in us) of the most recently received high pulse
if (pi.lastLowPulse != MAX_PULSE)
print_unsigned_long(pulse_to_microseconds(pi.lastLowPulse));
print(" us ");
}
// generate pulse output on pin D1
if (get_ms() - time_ms >= 20)
{
time_ms = get_ms();
set_digital_output(IO_D1, HIGH);
delay_us(high_pulse_us);
set_digital_output(IO_D1, LOW);
if (upcounting)
high_pulse_us += 10;
else
high_pulse_us -= 10;
if (high_pulse_us > 2000)
{
high_pulse_us = 2000;
upcounting = 0;
}
if (high_pulse_us < 1000)
{
high_pulse_us = 1000;
upcounting = 1;
}
}
}
}Everything about this program should work with the current release of the library except for the function pulse_to_microseconds(), which is being included in the next release.
- Ben