84 lines
1.9 KiB
Python
84 lines
1.9 KiB
Python
# SPDX-FileCopyrightText: 2024 Jeff Epler, written for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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"""A PIO demo that uses the FIFO in random access mode
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Random access mode is a new feature of the PIO peripheral of the RP2350.
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This demo is not compatible with the original RP2040 or Raspberry Pi
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Pico.
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Wiring:
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* LED with current limiting resistor on GP25 (Pico 2 standard location)
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The LED will blink in several patterns depending on the values loaded in the 'rxfifo' registers
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"""
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import array
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import time
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import board
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import rp2pio
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import adafruit_pioasm
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program = adafruit_pioasm.Program(
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"""
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.pio_version 1
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.set 1
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.fifo txget
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; LED on time taken from rxfifo[0]
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mov osr, rxfifo[0]
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mov x, osr
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set pins, 1
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xloop1:
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jmp x--, xloop1
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; LED off time taken from rxfifo[1]
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mov osr, rxfifo[1]
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mov x, osr
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set pins, 0
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xloop2:
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jmp x--, xloop2
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"""
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)
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def assign_uint32s(ar, off, *args):
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"""Assign multiple 32-bit registers within an AddressRange"""
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vv = b"".join(v.to_bytes(4, "little") for v in args)
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ar[off : off + 4 * len(args)] = vv
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print(program.pio_kwargs)
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sm = rp2pio.StateMachine(
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program.assembled,
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first_set_pin=board.GP25,
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frequency=10_000_000,
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**program.pio_kwargs,
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)
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fifo = sm.rxfifo
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# Set non-zero register entries & re-start the state machine at its offset.
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# this is needed because the default register value could represent a very long delay
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fifo[0:4] = b"\1\0\0\0"
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fifo[4:8] = b"\1\0\0\0"
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sm.run(array.array("H", [sm.offset]))
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while True:
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# equal blinks
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assign_uint32s(fifo, 0, 2000000, 2000000)
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time.sleep(1)
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# small on time
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assign_uint32s(fifo, 0, 1000000, 3000000)
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time.sleep(1)
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# small off time
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assign_uint32s(fifo, 0, 3000000, 1000000)
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time.sleep(1)
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# slower blinks
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assign_uint32s(fifo, 0, 3000000, 3000000)
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time.sleep(1)
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