S/PDIF DAC Headphone Amp for Raspberry Pi Pico

Overview

• Application of pico_spdif_rx project
• DAC Headphone Amp for SPDIF input
• DAC volume by rotary encoder
• Li-Po battery operation
• Auto power off when no-sync / no-signal timeout

Supported Board and Peripheral Devices

• Raspberry Pi Pico (rp2040)
• SPDIF Coaxial or TOSLINK (DLR1160 or equivalent) receiver
• PCM5102 DAC board
• FM5324, MH-CD42 or IP5306 Li-Po Charger board

Pin Assignment

PCM5102

Pico Pin #	GPIO	Function	Connection
21	GP16	BCK	to PCM5102 BCK (13)
22	GP17	LRCK	to PCM5102 LRCK (15)
23	GND	GND	GND
24	GP18	SDO	to PCM5102 DIN (14)

Rotary Encoder

Pico Pin #	Pin Name	Function	Connection
31	GP26	GPIO Input	A Pin
32	GP27	GPIO Input	B Pin
33	GND	GND	GND

Power Control

Pico Pin #	Pin Name	Function	Connection
29	GP22	GPIO Output	CHARGER_KEY_EN
34	GP28	GPIO Output	P5V_EN

Schematic

pico_spdif_dac_hpamp.pdf

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_dac_hpamp.git
> cd pico_spdif_dac_hpamp
> git submodule update -i
> cd ..

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_dac_hpamp
> mkdir build && cd build
> cmake -G "NMake Makefiles" ..
> nmake

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

Linux

• Build is confirmed with pico-sdk-dev-docker:sdk-2.0.0-1.0.0
• Confirmed with cmake-3.22.1 and arm-none-eabi-gcc (15:10.3-2021.07-4) 10.3.1

$ cd pico_spdif_dac_hpamp
$ mkdir build && cd build
$ cmake ..
$ make -j4

• Download "pico_spdif_dac_hpamp.uf2" on RPI-RP2 drive