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"""
This script uses the inline assembler to make the LEDs light up
in a pattern based on how they are multiplexed in rows/cols.
"""
# row pins: 13, 14, 15
# col pins: 4..12 inclusive
# GPIO words starting at 0x50000500:
# RESERVED, OUT, OUTSET, OUTCLR, IN, DIR, DIRSET, DIRCLR
@micropython.asm_thumb
def led_cycle():
b(START)
# DELAY routine
label(DELAY)
mov(r3, 0xa0)
lsl(r3, r3, 11)
label(delay_loop)
sub(r3, 1)
bne(delay_loop)
bx(lr)
label(START)
cpsid('i') # disable interrupts so we control the display
mov(r0, 0x50) # r0=0x50
lsl(r0, r0, 16) # r0=0x500000
add(r0, 0x05) # r0=0x500005
lsl(r0, r0, 8) # r0=0x50000500 -- this points to GPIO registers
mov(r1, 0b111)
lsl(r1, r1, 13) # r1=0xe000
str(r1, [r0, 8]) # pull all rows high
mov(r1, 1 << 4) # r1 holds current col bit
mov(r2, 9) # r2 holds number of cols left
label(loop_on)
str(r1, [r0, 12]) # pull col low to turn LEDs on
bl(DELAY) # wait
lsl(r1, r1, 1) # shift to next col
sub(r2, 1) # decrease col counter
bne(loop_on) # loop while there are still cols left
mov(r1, 1 << 4) # r1 holds current col bit
mov(r2, 9) # r2 holds number of cols left
label(loop_off)
str(r1, [r0, 8]) # pull col high to turn LEDs off
bl(DELAY) # wait
lsl(r1, r1, 1) # shift to next col
sub(r2, 1) # decrease col counter
bne(loop_off) # loop while there are still cols left
cpsie('i') # enable interrupts
for i in range(4):
led_cycle()
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