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FoamyGuyFoamyGuy
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Merge pull request #66 from timchinowsky/add_pioasm_i2c_codec
add codec example
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Diff for: ‎examples/pioasm_i2s_codec.py

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# SPDX-FileCopyrightText: 2024 Tim Chinowsky
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# SPDX-License-Identifier: MIT
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import array
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import board
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import rp2pio
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import adafruit_pioasm
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# Implement extended multichannel I2S interface like that used by audio codecs
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# such as the TAC5212. In extended I2S, "Left" and "Right" can each contain
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# multiple channels, so for instance 8 channels of audio can be sent as a "left"
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# containing 4 channels and a "right" containing 4 channels.
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# In this implementation the number of bits per sample, sample rate, and
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# number of channels can be independently specified. The number of channels must
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# be even, to divide evenly between left and right.
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# Ramped test data containing the requested number of sample sets (one set = one
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# sample for each channel) and spanning the specified number of bits will be generated
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# and sent out over I2S on the specified pins.
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# Data will be preceded and followed by a set of zeros for convenience.
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# (Some protocol analyzers have trouble analyzing serial data at the the beginning
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# and end of a data set)
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# At the same time that I2S data is sent out the out_pin, I2S data will be received
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# on the in_pin. If the output is looped back (connected) to the input, the data
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# received should be the same as the data sent.
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# Some samples run in loopback configuration:
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# bits per sample: 16
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# sample rate: 48000
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# channels: 4
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# sample sets: 4
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# actual sample frequency 47984.6 Hz
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# bit clock 3071017.0 Hz
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# write: 00000000 00000000 00000000 00000000
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# read: 00000000 00000000 00000000 00000000
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# write: 00000000 00001111 00002222 00003333
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# read: 00000000 00001111 00002222 00003333
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# write: 00004444 00005555 00006666 00007777
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# read: 00004444 00005555 00006666 00007777
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# write: 00008888 00009999 0000aaaa 0000bbbb
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# read: 00008888 00009999 0000aaaa 0000bbbb
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# write: 0000cccc 0000dddd 0000eeee 0000ffff
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# read: 0000cccc 0000dddd 0000eeee 0000ffff
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# write: 00000000 00000000 00000000 00000000
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# read: 00000000 00000000 00000000 00000000
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# bits per sample: 24
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# sample rate: 24000
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# channels: 8
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# sample sets: 5
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# actual sample frequency 23987.7 Hz
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# bit clock 4605642.0 Hz
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# write: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
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# read: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
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# write: 00000000 00069069 000d20d2 0013b13b 001a41a4 0020d20d 00276276 002df2df
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# read: 00000000 00069069 000d20d2 0013b13b 001a41a4 0020d20d 00276276 002df2df
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# write: 00348348 003b13b1 0041a41a 00483482 004ec4ec 00555554 005be5be 00627626
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# read: 00348348 003b13b1 0041a41a 00483482 004ec4ec 00555554 005be5be 00627626
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# write: 00690690 006f96f8 00762762 007cb7ca 00834834 0089d89c 00906904 0096f96c
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# read: 00690690 006f96f8 00762762 007cb7ca 00834834 0089d89c 00906904 0096f96c
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# write: 009d89d8 00a41a40 00aaaaa8 00b13b10 00b7cb7c 00be5be4 00c4ec4c 00cb7cb4
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# read: 009d89d8 00a41a40 00aaaaa8 00b13b10 00b7cb7c 00be5be4 00c4ec4c 00cb7cb4
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# write: 00d20d20 00d89d88 00df2df0 00e5be58 00ec4ec4 00f2df2c 00f96f94 00ffffff
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# read: 00d20d20 00d89d88 00df2df0 00e5be58 00ec4ec4 00f2df2c 00f96f94 00ffffff
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# write: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
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# read: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
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def i2s_codec( # pylint: disable=too-many-arguments
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channels=2,
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sample_rate=48000,
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bits=16,
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bclk_pin=None,
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out_pin=None,
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in_pin=None,
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):
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i2s_clock = sample_rate * channels * bits
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pio_clock = 4 * i2s_clock
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pio_code = """
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.program i2s_codec
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.side_set 2
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; at program start we initialize the bit count top
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; (which may be >32) with data
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; pulled from the input fifo
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pull noblock ; first empty the input fifo
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pull noblock
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pull noblock
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pull noblock
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out null, 32 ; then clear OSR so we can get a new value
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pull block ; then get the bit count top value from the fifo
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; /--- LRCLK
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; |/-- BCLK
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; ||
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mov x, osr; side 0b01 [1] ; save it in x
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out null, 32 side 0b00 [1]
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mov y, x side 0b01 [1] ; start of main loop (wrap target=8)
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bitloop1:
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out pins 1 side 0b00
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in pins 1 side 0b00
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jmp y-- bitloop1 side 0b01 [1]
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out pins 1 side 0b10
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in pins 1 side 0b10
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mov y, x side 0b11 [1]
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bitloop0:
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out pins 1 side 0b10
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in pins 1 side 0b10
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jmp y-- bitloop0 side 0b11 [1]
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out pins 1 side 0b00
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in pins 1 side 0b00
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"""
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pio_params = {
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"frequency": pio_clock,
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"first_out_pin": out_pin,
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"first_in_pin": in_pin,
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"first_sideset_pin": bclk_pin,
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"sideset_pin_count": 2,
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"auto_pull": True,
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"auto_push": True,
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"out_shift_right": False,
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"in_shift_right": False,
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"pull_threshold": bits,
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"push_threshold": bits,
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"wait_for_txstall": False,
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"wrap_target": 8,
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}
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pio_instructions = adafruit_pioasm.assemble(pio_code)
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i2s_clock = sample_rate * channels * bits
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pio_clock = 4 * i2s_clock
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pio = rp2pio.StateMachine(pio_instructions, **pio_params)
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return pio
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def spaced_samples(length, bits):
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max_int = (1 << bits) - 1
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if length == 1:
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return [0]
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step = max_int / (length - 1)
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result = [round(i * step) for i in range(length)]
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result[0] = 0
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result[-1] = max_int
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return result
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while True:
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print()
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BITS = int(input("# bits per sample: "))
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SAMPLE_RATE = int(input("# sample rate: "))
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CHANNELS = int(input("# channels: "))
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SAMPLE_SETS = int(input("# sample sets: "))
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n_samples = CHANNELS * SAMPLE_SETS
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buffer_type = "L"
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buffer_width = 32
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data = [0] * CHANNELS + spaced_samples(n_samples, BITS) + [0] * CHANNELS
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# initialize pio bit count top value by sending it at the start of output data
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bit_count_top = BITS * (CHANNELS // 2) - 2
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buffer_out = array.array(
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buffer_type, [bit_count_top] + [d << (buffer_width - BITS) for d in data]
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)
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buffer_in = array.array(buffer_type, [0] * len(data))
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PIO = i2s_codec(
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channels=CHANNELS,
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bits=BITS,
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sample_rate=SAMPLE_RATE,
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out_pin=board.D9,
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in_pin=board.D10,
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bclk_pin=board.D5, # L/R signal will be one pin higher, i.e. D6
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)
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print()
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print(f"# actual sample frequency {PIO.frequency/4/CHANNELS/BITS:9.1f} Hz")
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print(f"# bit clock {PIO.frequency/4:9.1f} Hz")
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print()
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PIO.write_readinto(buffer_out, buffer_in)
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start = 0
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line_length = CHANNELS
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while start < len(buffer_in):
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print("# write: ", end="")
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for i in range(start, min(len(data), start + line_length)):
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print(f"{data[i]:0{buffer_width/4}x} ", end=" ")
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print()
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print("# read: ", end="")
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for i in range(start, min(len(buffer_in), start + line_length)):
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print(f"{buffer_in[i]:0{buffer_width/4}x} ", end=" ")
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print()
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print()
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start += line_length
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PIO.deinit()
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del PIO

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