Raspberry Pi Pico spdif_rx

Overview

• SPDIF 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)
• SPDIF Coaxial or TOSLINK Rx module (DLR1160 or equivalent)

Pin Assignment & Connection

SPDIF Rx

Pico Pin #	GPIO	Function	Connection
20	GP15	DATA	from SPDIF data

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"
• Build is confirmed only in Developer Command Prompt for VS 2019 and Visual Studio Code on Windows enviroment
• Put "pico-sdk", "pico-examples" (, "pico-extras" and "pico-playground") on the same level with this project folder.
• Confirmed under Pico SDK 1.4.0

> git clone -b master https://github.com/raspberrypi/pico-sdk.git
> cd pico-sdk
> git submodule update -i
> cd ..
> git clone -b master https://github.com/raspberrypi/pico-examples.git
>
> git clone https://github.com/raspberrypi/pico-extras.git
> cd pico-extras
> git submodule update -i
> cd ..
> 
> git clone -b main https://github.com/elehobica/pico_spdif_rx.git

• Lanuch "Developer Command Prompt for VS 2019"

> cd pico_spdif_rx
> cd samples/xxxxx  # sample project directory
> mkdir build
> cd build
> cmake -G "NMake Makefiles" ..
> nmake

• Put "pico_spdif_rx.uf2" on RPI-RP2 drive

Decode output format

• 32bit output for each SPDIF 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 SPDIF frame and number of parity errors while decoding

spdif_to_i2s_32b

• convert SPDIF input to I2S 32bit output