69 lines
1.5 KiB
Python
69 lines
1.5 KiB
Python
# SPDX-FileCopyrightText: 2021 Scott Shawcroft, written for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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import array
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import math
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import time
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import board
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import digitalio
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import rp2pio
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import adafruit_pioasm
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trigger = digitalio.DigitalInOut(board.D4)
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trigger.switch_to_output(True)
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# Generate one period of sine wav.
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length = 8000 // 440
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# signed 16 bit
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s16 = array.array("h", [0] * length)
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for i in range(length):
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s16[i] = int(math.sin(math.pi * 2 * i / length) * (2**15))
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print(s16[i])
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program = """
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.program i2s_with_hold
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.side_set 2
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; Load the next set of samples
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; /--- LRCLK
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; |/-- BCLK
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; ||
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pull noblock side 0b01 ; Loads OSR with the next FIFO value or X
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mov x osr side 0b01 ; Save the new value in case we need it again
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set y 14 side 0b01
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bitloop1:
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out pins 1 side 0b10 [2]
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jmp y-- bitloop1 side 0b11 [2]
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out pins 1 side 0b10 [2]
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set y 14 side 0b11 [2]
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bitloop0:
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out pins 1 side 0b00 [2]
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jmp y-- bitloop0 side 0b01 [2]
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out pins 1 side 0b00 [2]
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"""
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assembled = adafruit_pioasm.assemble(program)
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dac = rp2pio.StateMachine(
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assembled,
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frequency=800000 * 6,
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first_out_pin=board.D12,
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first_sideset_pin=board.D10,
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sideset_pin_count=2,
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auto_pull=False,
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out_shift_right=False,
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pull_threshold=32,
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wait_for_txstall=False,
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)
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trigger.value = False
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dac.write(s16)
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time.sleep(1)
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dac.stop()
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trigger.value = True
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print("done")
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