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Raspberry Pi Pico S/PDIF receiver library

Overview

  • S/PDIF receiver by rp2040 PIO function
  • format: 2ch, 16bit or 24bit
  • sampling frequency: 44.1 KHz, 48.0 KHz, 88.2 KHz, 96.0 KHz, 176.4 KHz, 192.0 KHz
  • signal detecting function for all supported sampling frequencies

Supported Board and Peripheral Devices

  • Raspberry Pi Pico (rp2040)
  • S/PDIF Coaxial or TOSLINK Rx module (DLR1160 or equivalent)

Pin Assignment & Connection

S/PDIF Rx

Pico Pin # GPIO Function Connection
20 GP15 DATA from S/PDIF data

SPDIF_Rx_Schematic

Notes:

  • 74HC04 should be genuine device, otherwise (counterfeit device) it could not work at higher sampling frequencies.
  • if TOSLINK only, direct connection from module output to GP15 will work as well.

How to build

  • See "Getting started with Raspberry Pi Pico"
  • Put "pico-sdk", "pico-examples" and "pico-extras" on the same level with this project folder.
  • Set environmental variables for PICO_SDK_PATH, PICO_EXTRAS_PATH and PICO_EXAMPLES_PATH
  • Confirmed with Pico SDK 2.0.0
> git clone -b 2.0.0 https://github.com/raspberrypi/pico-sdk.git
> cd pico-sdk
> git submodule update -i
> cd ..
> git clone -b sdk-2.0.0 https://github.com/raspberrypi/pico-examples.git
>
> git clone -b sdk-2.0.0 https://github.com/raspberrypi/pico-extras.git
> 
> git clone -b main https://github.com/elehobica/pico_spdif_rx.git

Windows

  • Build is confirmed with Developer Command Prompt for VS 2022 and Visual Studio Code on Windows environment
  • Confirmed with cmake-3.27.2-windows-x86_64 and gcc-arm-none-eabi-10.3-2021.10-win32
  • Lanuch "Developer Command Prompt for VS 2022"
> cd pico_spdif_rx\samples\xxxxx  # sample project directory
> mkdir build && cd build
> cmake -G "NMake Makefiles" ..
> nmake
  • Put "xxxxx.uf2" on RPI-RP2 drive

Linux

$ cd pico_spdif_rx/samples/xxxxx  # sample project directory
$ mkdir build && cd build
$ cmake ..
$ make -j4
  • Download "xxxxx.uf2" on RPI-RP2 drive

Decode output format

  • 32bit output for each S/PDIF sub frame including header, audio data, AUX, VUCP
  • see comments in spdif_rx.pio for further detail

Sample projects

detect_samp_freq

  • display sampling frequency, C bits of S/PDIF frame and number of parity errors while decoding

spdif_to_i2s_32b

  • convert S/PDIF input to I2S 32bit output