Diff: PololuLedStrip.cpp

Revision:

19:46d7ab0ba3e7

Parent:

17:91fb934a2166

--- a/PololuLedStrip.cpp	Fri Mar 01 05:17:02 2013 +0000
+++ b/PololuLedStrip.cpp	Wed Oct 09 01:13:49 2013 +0000
@@ -2,8 +2,8 @@
 
 bool PololuLedStrip::interruptFriendly = false;
 
-// The three timed delays, in units of half-cycles.
-uint8_t led_strip_write_delays[3];
+// The two timed delays, in units of half-cycles.
+uint8_t led_strip_write_delays[2];
 
 void PololuLedStrip::calculateDelays()
 {
@@ -11,28 +11,26 @@
 
     if (f_mhz <= 48)
     {
-        // The delays below result in 800/1590 ns pulses and a 2500 ns period on the mbed NXP LPC11U24.        
+        // The delays below result in 360/1120 ns pulses and a 1880 ns period on the mbed NXP LPC11U24.        
         led_strip_write_delays[0] = 0;
         led_strip_write_delays[1] = 0;
-        led_strip_write_delays[2] = 5;
     }
     else
     {
         // Try to generally compute what the delays should be for a ide range of clock frequencies.
         
         // The fudge factors below were experimentally chosen so that we would have
-        // ~700/1300 ns pulses and a ~2500 ns period on the mbed NXP LPC1768 (96 MHz Cortex-M3).
+        // ~100/840 ns pulses and a ~1430 ns period on the mbed NXP LPC1768 (96 MHz Cortex-M3).
         // There seem to be some ~100 ns inconsistencies in the timing depending on which example program is
         // running; the most likely explanation is some kind of flash caching that affects the timing.
         // If you ever change these numbers, it is important to check the the subtractions below
-        // will not overflow in the worst case, which is f_mhz = 49.
-        led_strip_write_delays[0] = 700*f_mhz/1000 - 23;
-        led_strip_write_delays[1] = 600*f_mhz/1000 - 18;
-        led_strip_write_delays[2] = 1200*f_mhz/1000 - 33;    
+        // will not overflow in the worst case (smallest possible f_mhz).
+        led_strip_write_delays[0] = 750*f_mhz/1000 - 33;
+        led_strip_write_delays[1] = 550*f_mhz/1000 - 20;    
     }
  
     // Convert from units of cycles to units of half-cycles; it makes the assembly faster.   
-    for(int i = 0; i < 3; i++)
+    for(int i = 0; i < 2; i++)
     {
         led_strip_write_delays[i] <<= 1;
     }