125 lines
3.6 KiB
Python
125 lines
3.6 KiB
Python
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import rp2
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######################################################
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## Define I2S PIO machines
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## 16-bit slots, data
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## read on falling edge of bit clock
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######################################################
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@rp2.asm_pio(sideset_init=[rp2.PIO.OUT_LOW]*2, fifo_join=rp2.PIO.JOIN_RX)
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## bitclock and LR clock on the sidesets, respectively
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def i2s_read_pio():
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nop()[3] ## delay to sync up with write PIO -- empirically determined
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wrap_target()
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set(y,14) .side(0b00)[1] ## send 32 bits per LR read
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label("L")
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in_(pins, 1) .side(0b01)[1] ## Left, bits
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jmp(y_dec, "L") .side(0b00)[1]
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in_(pins, 1) .side(0b11)[1]
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set(y,14) .side(0b10)[1]
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label("R")
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in_(pins,1) .side(0b11)[1] ## right, bits
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jmp(y_dec, "R") .side(0b10)[1]
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in_(pins,1) .side(0b01)
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push(noblock) ## noblock keeps PIOs in sync
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wrap()
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## 10
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@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW, fifo_join=rp2.PIO.JOIN_TX)
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## runs lockstep with read pio, spits out data when it's got it, zeros otherwise
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def i2s_write_pio():
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wrap_target()
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pull(noblock) ## noblock keeps PIOs in sync
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set(y,14) ## send 16 bits per LR clock
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label("L")
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out(pins,1) [1] ## Left, bits
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jmp(y_dec, "L") [1]
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out(pins,1) [1]
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set(y,14) [1]
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label("R")
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out(pins,1) [1]
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jmp(y_dec, "R") [1]
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out(pins,1) [1]
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wrap()
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## 19
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@rp2.asm_pio(in_shiftdir=1, out_shiftdir=1)
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def bit_flipper_pio():
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## takes in two 16-bit as signed/unsigned integers
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## converts them by flipping MSBit of each 16-bitter
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## tailored for reading X/Y channel from DAC and fitting
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## the result on the (unsigned 8bit) screen
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pull()
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set(y,1)
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label("twice")
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in_(osr, 15) ## copy 15 LSB unchanged to output
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out(null, 15) ## discard 15 bits from OSR to keep pace
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mov(osr, invert(osr)) ## inverted what's left
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in_(osr, 1) ## copy out one inverted bit
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out(null, 1) ## drop that bit from OSR
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mov(osr, invert(osr)) ## reinvert for the next word
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jmp(y_dec, "twice")
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push()
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## 29
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########################################################
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## Pixel Pusher: Handle Screen Command
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## Takes commands and data
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## sends it to the screen pretty fast
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## Format:
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# 0 2A 0 X
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# 0 2B 0 Y
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# 0 2C C1 C2
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## Screen expects 2A 0 X 0 X 2B 0 Y 0 Y 2C C1 C2
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## with the commands framed by the DC line going low
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## This PIO ignores the first byte,
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## transmits the second, framed by DC,
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## then doubles the second pair
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## This means it actually transmits C1 C2 C1 C2, but
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## the screen doesn't seem to care (hack, hack!)
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########################################################
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@rp2.asm_pio(out_init=rp2.PIO.OUT_LOW, set_init=rp2.PIO.OUT_HIGH,
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sideset_init=rp2.PIO.OUT_LOW, autopull=True, autopush=True)
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def handle_screen_command():
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pull(block).side(0)
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out(null, 8).side(0) ## drop initial zeros
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set(pins, 0).side(0) ## DC set low, CMD mode
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set(y,7).side(0) ## send 8 command bits
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label("send_cmd")
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out(pins, 1).side(0)
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jmp(y_dec, "send_cmd").side(1)
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set(pins, 1).side(0) ## DC set high, data mode
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mov(x, osr).side(0) ## copy next bytes over, b/c going to send them twice
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mov(osr, x).side(0) ## copy next bytes over, b/c going to send them twice
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set(y,15).side(0) ## send 0, X
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label("one_time")
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out(pins, 1).side(0)
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jmp(y_dec, "one_time").side(1)
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mov(osr,x).side(0) ## copy bytes back
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set(y,15).side(0) ## re-send 0, X
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label("one_more_time")
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out(pins, 1).side(0)
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jmp(y_dec, "one_more_time").side(1)
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# 16
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