Revision 6:9d0530b7dae2, committed 2013-03-01

Comitter:

DavidEGrayson

Date:

Fri Mar 01 00:31:24 2013 +0000

Parent:

5:690fdfb595de

Child:

7:9a088f042ee0

Commit message:

Successfully read the delay amount from a table.

Changed in this revision

--- a/PololuLedStrip.cpp	Fri Mar 01 00:05:26 2013 +0000
+++ b/PololuLedStrip.cpp	Fri Mar 01 00:31:24 2013 +0000
@@ -5,6 +5,8 @@
 // TODO: read clock frequency from SystemCoreClock and use that to make this work on different boards.
 // calculate the three delays needed and pass them to the assembly.  The assembly can implement them with computed jumps.
 
+uint8_t led_strip_write_delays[3];
+
 PololuLedStrip::PololuLedStrip(PinName pinName)
 {
     gpio_init(&gpio, pinName, PIN_OUTPUT);
@@ -14,6 +16,12 @@
 {
     __disable_irq();   // Disable interrupts temporarily because we don't want our pulse timing to be messed up.
     
+    int f = SystemCoreClock/1000000;
+    led_strip_write_delays[0] = 700*f/1000 - 10;
+    led_strip_write_delays[1] = 600*f/1000 - 10;
+    led_strip_write_delays[2] = 1200*f/1000 - 10;
+    led_strip_write_delays[0] = 59;
+    
     while(count--)
     {
         led_strip_write_color(colors++, gpio.reg_set, gpio.reg_clr, gpio.mask);

--- a/led_strip_write_color.s	Fri Mar 01 00:05:26 2013 +0000
+++ b/led_strip_write_color.s	Fri Mar 01 00:31:24 2013 +0000
@@ -1,5 +1,6 @@
     AREA asm_func, CODE, READONLY
     EXPORT led_strip_write_color
+    IMPORT led_strip_write_delays
 
 led_strip_write_color
     ; Register usage:
@@ -10,12 +11,13 @@
     ;   R3:  pin mask
     ; Additionally, we use these registers:
     ;   R4:  temporary register
+    ;   R5:  temporary register
     ;   R7:  the number of bits we still need to send
     ;   R12: shift register that holds the 24-bit color
     ;   R13: Link Register, holds return addresses.
     
     
-    push    {r4, r12, r7, lr}
+    push {r4, r5, r12, r7, lr}
    
     ldr r12, [r0]      ; Read the next color.
     rbit r12, r12      ; Reverse the order of the bits.
@@ -26,8 +28,11 @@
     str r3, [r1]       ; Drive the line high.
     rrxs r12, r12      ; Rotate right through carry.
     
+    ldr r5, =led_strip_write_delays
+    ldrb r5, [r5, #0]
+    lsl r5, r5, #1
     ldr r4, =delay_region_end
-    sub r4, r4, #59*2
+    sub r4, r4, r5
     blx r4
     
     it cc                ; If the bit to send it 0...
@@ -44,11 +49,11 @@
     add r4, r4, #68
     blx r4
     
-    subs r7, r7, #1            ; Decrement the loop counter.
+    subs r7, r7, #1           ; Decrement the loop counter.
     bne send_led_strip_bit    ; Send another bit if we have not reached zero.
     
 led_strip_asm_end
-    pop {r4, r12, r7, lr}
+    pop {r4, r5, r12, r7, lr}
     bx lr