Datasheet Codec

 

Datasheet Codec

Overview

The HiFiBerry Codec Stage is a audio codec (DAC and ADC) for the Raspberry Pi (newer models with 40 pin GPIO connector). This is a special sound card for the Raspberry Pi, optimised for one specific use case: affordable audio recording and playback. It is designed specifically for OEMs that require analog input and output capabilities at an affordable price.

Please note that this board isn’t available to end users. If you’re a business customer, please contact us to discuss your specific needs.

Facts

  • Stereo input and output
  • Hardware volume control for DAC and ADC. You can control the input and output parameters using “alsamixer” or any application that supports ALSA mixer controls.
  • Connects directly to the Raspberry Pi, no additional cables needed
  • No soldering, comes as a pre-fabricated kit.
  • Compatible with all Raspberry Pi models with a 40-pin GPIO connector
  • Directly powered from the Raspberry Pi, no additional power supply. Power supply via I/O board possible if Pi’s power jack isn’t expose to the outside of your enclosure
  • Mic bias voltage for the use with electret microphones

Hardware

1Analog input (connected in parallel to the phone jack input)
2Microphone selector (onboard or external)
3Analogue output (headphone)
4Microphone bias voltage

Specifications

Maximum input voltage2.1Vrms
Maximum output voltage2.1Vrms
Line in ADC signal-to-noise ratio85 dBtypical
DAC signal-to-noise ratio100dBtypical (headphone 16 Ohm)
Line in ADC THD+N-70 dBtypical
DAC THD+N-80dBtypical (headphone 16 Ohm)
Frequency response20Hz-20kHz(-3dB)
Input gain0-62.5dB
Power consumption<0.3W
Sample rates32,44.ö1,48 and 96 kHz

Configuration

Overlay for config.txt:
dtoverlay=fe-pi-audio

Mixer controls

There are lots of mixer controls, it’s important to set these correctly.

Simple record/playback settings
amixer set 'Headphone' 103
amixer set 'Headphone Mux' 'DAC'
amixer set 'PCM' 192
amixer set 'Lineout' 0
amixer set 'Mic' 1
amixer set 'Capture' 6
amixer set 'Capture Attenuate Switch (-6dB)' 'on'
amixer set 'Capture Mux' 'LINE_IN'
amixer set 'Digital Input Mux' 'I2S'

Note that the RCA output connector and the pin header is connected to the Headphone output, not to the line-out of the codec!

Recording from the onboard-microphone

Set the jumper first to select the onboard microphone:

amixer set 'Capture Mux' 'MIC_IN'

Record 5 seconds of audio and play back recording

arecord -c 2 -r 44100 -f S16_LE -d 5 x.wav; aplay x.wav
Recording from an external microphone

Set the jumper to “external”. Depending on the microphone you’re using you might have to set the Mic bias jumper to enable a bias voltage to your microphone (electret microphones will need this, dynamic microphones should not have Mic bias enabled).

You can use the same play/record command as in the previous example.

Media

Additional documentation

Note that this board is not available to the general public. If you’re an OEM that requires a large number of these boards, please contact us.

Last updated: June 15, 2021