Revision 13:1f65330abe92, committed 2013-07-23

Comitter:

heroic

Date:

Tue Jul 23 22:32:14 2013 +0000

Parent:

12:7ebd51549c04

Child:

14:c97261a9a282

Commit message:

Rework timing for constant execution time; do direct bitband writes for improved speed; change interrupt handling (turns out we can't have interrupts during an entire strip push, not just between bits).; ; Now works!

Changed in this revision

--- a/WS2811.cpp	Thu Apr 11 22:16:07 2013 +0000
+++ b/WS2811.cpp	Tue Jul 23 22:32:14 2013 +0000
@@ -27,6 +27,14 @@
     printf("ws2811:  1000 iters took %d usec.\n", i);
     bogocal = (1000 / (onewire_speed_multiplier * i * 4.2)); // iterations per bitcell (417 nsec)
     printf("ws2811:  calibrating to %d bogojiffies.\n", bogocal);
+    
+    data_mask = dat.get_mask();
+    clock_mask = clk.get_mask();
+    data_set = dat.get_set();
+    data_clr = dat.get_clr();
+    clock_set = clk.get_set();
+    clock_clr = clk.get_clr();
+    
 }
 
 /*
@@ -34,7 +42,7 @@
  */
  
 void WS2811::write(uint8_t byte) {
-    __disable_irq();
+    
     for (int i=0; i<8; i++) {
         if (byte & 0x80)
             writebit(1);
@@ -42,26 +50,26 @@
             writebit(0);
         byte <<= 1;
     }
-    __enable_irq();
 }
 
 inline void WS2811::celldelay(void) {
-    for (int i = 0; i<bogocal; i++)
+    for (volatile int i = 0; i<bogocal; i++)
         /* do nothing */ ;
 }
 
-void WS2811::writebit(bool bit) {
+inline void WS2811::writebit(bool bit) {
     // first cell is always 1
-    dat = 1;
+    (*data_set) = data_mask;
     celldelay();
     if (bit) {
+        (*clock_set) = data_mask; // dummy, we don't care but must take constant time
         celldelay();
     } else {
-        dat=0;
+        (*data_clr) = data_mask;
         celldelay();
     }
     // last cell is always 0
-    dat=0;
+    (*data_clr) = data_mask;
     celldelay();
 }
 
@@ -82,10 +90,11 @@
     uint16_t i, nl3 = numLEDs * 3; // 3 bytes per LED
     while (guardtime.read_us() < 50)
         /* spin */;
+    __disable_irq();
     for (i=0; i<nl3; i++ ) {
         write(pixels[i]);
     }
-
+    __enable_irq();
     guardtime.reset();
 }
 

--- a/WS2811.h	Thu Apr 11 22:16:07 2013 +0000
+++ b/WS2811.h	Tue Jul 23 22:32:14 2013 +0000
@@ -37,6 +37,12 @@
  private:
   DigitalOut dat;
   DigitalOut clk;
+  __IO uint32_t *data_set;
+  __IO uint32_t *clock_set;
+  __IO uint32_t *data_clr;
+  __IO uint32_t *clock_clr;
+  uint32_t clock_mask;
+  uint32_t data_mask;
   void write(uint8_t byte);
   void writebit(bool bit);
   void celldelay(void);