Internet radio: How to connect I2S DAC to Raspberry Pi

To build your DIY internet radio, you connect Raspberry Pi to some DAC (digital - analog converter) and add any audio speakers with amplifier. To play music use any ‘headless’ music player you like (volumio, rune audio, max2play etc). You control this players from your phone, so no need in any knobs on the intenet radio box, you can hide it somewhere.

You need DAC because Raspberry Pi has very poor sound quality from integrated 3.5mm headphones jack.

Alternative if you do not want to mess with I2S DAC

You can use any HDMI-Video/audio adapter (search on aliexpress for “hdmi rca”. This is a small box with HDMI input and RCA output (yellow for video, red and white for audio). With HDMI cable this is the same money as I2S DAC.

In this case you connect Raspberry Pi HDMI to this adapter and select in your music player to output sound to HDMI.

I2S DAC PCM5102 on aliexpress

Search on aliexpress for “Raspberry Pi PCM5102”.

Of cause you can buy HiFiBerry for $35. But aliexpress models four(!) times cheaper.

PCM5102 vs PCM5122

Chinese boards are based on the same IC (PCM5102) as early HiFiBerry (DAC). New HiFiBerry (DAC+) is based on PCM5122 the main difference in witch is hardware volume control. If you control volume from your amplifier (the best for sound quality) you do not need the option. If you want to control volume from your volumio or other music player you can switch on software volume control. In theory this is bad for sound quality but in practice I do not think you will see the difference.

RCA 3.5mm headphones jack

Sellers claim that this is Raspberry Pi HAT extensions, but that is not true. You connect them to HAT socket on Raspberry Pi, but you need some wiring, you cannot just insert them as HiFiBerry.

Raspberry Pi A/B

On the very early Raspberry Pi version the pins that you need to connect I2S DAC were somethere on the board, but not in any socket. I do not think that you have such an old board so below I describe more modern ones.

Raspbery Pi before “+” version has the pins on 8-pins P5 socket, which is below main HAT 26-pins socket P1.

In many cases you have to solder P5 for yourself: video from HiFiBerry.

Take into account that it is supposed to be soldered on back side of the board (in the video above they solder it on opposite front side). Because of that odd/even pins in P5 is opposite as in P1. You can check youself - on P5-1 pin should be 5v, on P5-2 3.3v, and last pins of P5, P5-7 & P5-8 are ground.

Raspberry Pi A+/B+, Raspberry Pi 2, Raspberry Pi 3, Raspberry Pi Zero

All pins you need for I2S DAC are in main 40-pins HAT socket. It’s name now J8 and it consists of all 26 pins from old P1, and additional pins.

How to connect I2S DAC to Raspberry Pi

1st DAC version (with fewer pins):

DAC Pi A/B   Pi A+/B+, Pi2, Pi3, PiZ   PCM5102
Vcc (+5v) P5-1 J8-2  
+3.3v (not used, just to check youself)   P5-2 J8-1  
BCK P5-3 J8-12 Audio data bit clock input
LRCK(LCK) P5-4 J8-35 Audio data word clock input
DATA(DIN) P5-6 J8-40 Audio data input
Gnd P5-7 J8-39  

In the board description aliexpress seller wrote that BCK & DATA marked inverse. But in fact I connected them as marked (BCK is the last pin in DAC’s socket) and everything works fine.

2nd DAC:

Connect additional pins as:

DAC Pi A/B   Pi A+/B+, Pi2, Pi3, PiZ   PCM5102
GND P1-6 J8-6  
FLT (gnd) P1-14 J8-14 Filter select : Normal latency (Low) / Low latency (High)
DMP (gnd) P5-8 J8-20 ?De-emphasis control for 44.1kHz sampling rate(1): Off (Low) / On (High)
SCL P1-5 J8-5 ?System clock input
FMT (gnd) P1-18 J8-18 Audio format selection : I2S (Low) / Left justified (High)
XMT (3.3v)   P1-1 J8-1  

If you want here is all pins description: RPi Low-level peripherals.

PCM5102 datasheet

How to setup I2S DAC in Volumio