Tomás Vega
Forked PololuLedStrip and modified it to work with the KL25Z. Renamed it to Adafruit_NeoPixel.
Fork of
PololuLedStrip
by 
David Grayson
led_strip_write_color.s
- Committer:
- DavidEGrayson
- Date:
- 2013-02-28
- Revision:
- 4:d3b60bd43811
- Parent:
- 0:06475317f283
- Child:
- 5:690fdfb595de
File content as of revision 4:d3b60bd43811:
AREA asm_func, CODE, READONLY
EXPORT led_strip_write_color
led_strip_write_color
push {r4, 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
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it cc ; If the bit to send it 0...
strcc r3, [r2] ; Drive the line low.
nop
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it cs ; If the bit to send is 1...
strcs r3, [r2] ; Drive the line low.
ldr r4, =delay_region
add r4, r4, 34*2
blx r4
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 {r4, r12, r7}
bx lr
delay_region
; The following is 128 no-ops
nop
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bx lr ; return
END