David Knight
This library lets you control the addressable RGB LED strips from Pololu Robotics. Forked to add selectable colour order (Support RGB or GRB Leds)
Fork of
PololuLedStrip
by 
David Grayson
Diff: led_strip_write_color.s
- Revision:
- 0:06475317f283
- Child:
- 4:d3b60bd43811
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/led_strip_write_color.s Wed Feb 27 00:28:26 2013 +0000
@@ -0,0 +1,285 @@
+ AREA asm_func, CODE, READONLY
+ EXPORT led_strip_write_color
+
+led_strip_write_color
+ push {r12, r7}
+
+ ldr r12, [r0] ; Read the next color.
+ rbit r12, r12 ; Reverse the order of the bits.
+ rev r12, r12 ; Reverse the order of the bytes.
+ mov r7, #24 ; Initialize the loop counter register.
+
+send_led_strip_bit
+ str r3, [r1] ; Drive the line high.
+ rrxs r12, r12 ; Rotate right through carry.
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
+ nop
+ nop
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+
+ nop
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+
+ nop
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+
+ nop
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+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
+ nop
+ nop
+ nop
+
+ it cc ; If the bit to send it 0...
+ strcc r3, [r2] ; Drive the line low.
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
+ nop
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+
+ nop
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+ nop
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+
+ nop
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+ nop
+ nop
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+
+ it cs ; If the bit to send is 1...
+ strcs r3, [r2] ; Drive the line low.
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
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+
+ nop
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+ nop
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+
+ nop
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+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
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+
+ nop
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+ nop
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+ nop
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+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+
+ sub r7, r7, #1 ; Decrement the loop counter.
+ cbz r7, led_strip_asm_end ; If we have sent 24 bits, go to the end.
+ b send_led_strip_bit ; Otherwise, go back and send another bit.
+
+led_strip_asm_end
+ pop {r12, r7}
+ bx lr
+
+ END
\ No newline at end of file