Jeff Epler
5a7e52ced3
This example requires https://github.com/adafruit/circuitpython/pull/4329 to be merged in order to work
119 lines
2.9 KiB
Python
119 lines
2.9 KiB
Python
# SPDX-FileCopyrightText: 2021 Jeff Epler, written for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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#
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# This example is adapted in part from micropython:
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# https://github.com/micropython/micropython/pull/6894/files
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import adafruit_pioasm
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import board
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import rp2pio
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import array
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import digitalio
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class IncrementalEncoder:
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_state_look_up_table = array.array(
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"b",
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[
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# Direction = 1
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0, # 00 to 00
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-1, # 00 to 01
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+1, # 00 to 10
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+2, # 00 to 11
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+1, # 01 to 00
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0, # 01 to 01
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+2, # 01 to 10
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-1, # 01 to 11
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-1, # 10 to 00
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+2, # 10 to 01
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0, # 10 to 10
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+1, # 10 to 11
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+2, # 11 to 00
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+1, # 11 to 01
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-1, # 11 to 10
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0, # 11 to 11
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# Direction = 0
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0, # 00 to 00
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-1, # 00 to 01
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+1, # 00 to 10
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-2, # 00 to 11
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+1, # 01 to 00
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0, # 01 to 01
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-2, # 01 to 10
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-1, # 01 to 11
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-1, # 10 to 00
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-2, # 10 to 01
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0, # 10 to 10
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+1, # 10 to 11
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-2, # 11 to 00
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+1, # 11 to 01
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-1, # 11 to 10
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0, # 11 to 11
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],
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)
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_sm_code = adafruit_pioasm.assemble(
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"""
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again:
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in pins, 2
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mov x, isr
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jmp x!=y, push_data
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mov isr, null
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jmp again
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push_data:
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push
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mov y, x
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"""
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)
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_sm_init = adafruit_pioasm.assemble("set y 31")
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def __init__(self, pin_a, pin_b):
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if not rp2pio.pins_are_sequential([pin_a, pin_b]):
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raise ValueError("Pins must be sequential")
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self._sm = rp2pio.StateMachine(
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self._sm_code,
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160_000,
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init=self._sm_init,
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first_in_pin=pin_a,
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in_pin_count=2,
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pull_in_pin_up=0b11,
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in_shift_right=False,
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)
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self._counter = 0
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self._direction = 0
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self._lut_index = 0
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self._buffer = bytearray(1)
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def _update_state_machine(self, state):
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lut_index = self._lut_index | (state & 3)
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lut = self._state_look_up_table[lut_index]
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self._counter += lut
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if lut:
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self._direction = 1 if (lut > 0) else 0
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self._lut_index = ((lut_index << 2) & 0b1100) | (self._direction << 4)
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def deinit(self):
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self._sm.deinit()
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@property
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def value(self):
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while self._sm.in_waiting:
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self._sm.readinto(self._buffer)
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self._update_state_machine(self._buffer[0])
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return self._counter
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encoder = IncrementalEncoder(board.GP2, board.GP3)
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old_value = None
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while True:
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gen()
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value = encoder.value
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if old_value != value:
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print("Encoder:", value)
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old_value = value
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