Hopspitfire at 05:59, 31 July 2009

2009-07-31T05:59:11Z

Hopspitfire: New page: As mentioned in Controlling LEDs from the Shell], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twid...

2009-07-21T23:15:52Z

New page: As mentioned in [Controlling LEDs from the Shell], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twid...

New page

As mentioned in [[[controlling-leds-from-the-shell|Controlling LEDs from the Shell]]], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twiddling the LEDs using these endpoints, check out:

http://www.jasonlebrun.info/files/leds_demo.gz

Just copy the program to your Palm Pre, and then:
<pre><nowiki>
gunzip leds_demo.gz
chmod u+x leds_demo
./leds_demo
</nowiki></pre>

The LEDS are controlled by a low power special-purpose LED driver IC, the LP8501. It's controlled by the i2c bus. It allows preset programs to do things like fade-ins and fade-outs without requiring CPU intervention. I'm investigating it more, stay tuned.

Since the source is short, I'll post it right here:

<pre><nowiki>
#include "stdio.h"
#include "math.h"

int main(int argc, char** argv) {

int i = 0, val = 0, phase1=120, phase2=240, s=1000;
FILE *left_led, *right_led, *center_led;
char buf[10];
float PI = 3.14159;

if(argc < 4) {
puts("Usage: leds_demo delay(us) led2_offset led3_offset");
puts("Phase is in degrees around a circle. 120, 240 for perfect spacing");
puts("I.E.: leds_demo 1000 120 240");
puts("This example will be run now");
} else {
s = atoi(argv[1]);
phase1 = atoi(argv[2]);
phase2 = atoi(argv[3]);
}
left_led = fopen("/sys/class/leds/core_navi_left/brightness", "w");
right_led = fopen("/sys/class/leds/core_navi_right/brightness", "w");
center_led = fopen("/sys/class/leds/core_navi_center/brightness", "w");
while(1) {
val = sin(i*2*PI/360.0)*32+32;
sprintf(buf, "%d\n", val);
fwrite(buf, strlen(buf), 1, left_led);
rewind(left_led);

val = sin((i+phase1)*2*PI/360.0)*32+32;
sprintf(buf, "%d\n", val);
fwrite(buf, strlen(buf), 1, center_led);
rewind(right_led);

val = sin((i+phase2)*2*PI/360.0)*32+32;
sprintf(buf, "%d\n", val);
fwrite(buf, strlen(buf), 1, right_led);
rewind(center_led);

i++;
usleep(s);
}

}

</nowiki></pre>

← Older revision		Revision as of 05:59, 31 July 2009
Line 1:		Line 1:
−	As mentioned in [[[controlling-leds-from-the-shell\|Controlling LEDs from the Shell]]], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twiddling the LEDs using these endpoints, check out:	+	As mentioned in [[controlling-leds-from-the-shell\|Controlling LEDs from the Shell]], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twiddling the LEDs using these endpoints, check out:

	http://www.jasonlebrun.info/files/leds_demo.gz		http://www.jasonlebrun.info/files/leds_demo.gz

More on Leds - Revision history

Hopspitfire at 05:59, 31 July 2009

Hopspitfire: New page: As mentioned in Controlling LEDs from the Shell], there are some sysfs endpoints for controlling the LEDs. For a small example of a native program twid...