DigiAudioPi - digital audio transmitters for Raspberry Pi

The DigiPi is one of digital audio transmitters for Raspberry Pi. The DigiPi is a module based on the wolfson WM8804 chip, and the DigiPi can support up to 24bit 192 kHz PCM data. The DigiPi module powered from Raspberry Pi and supplied all ICs via linear regulator. The oscillator for WM8804 IC selects TCXO with low-noise linear regulator.

[Digital Output]

The DigiPi module have two kinds digital audio output, COAX (SPDIF) and I2S bus(but without MCLK). For providing galvanic isolation, the COAX output select muRata DA101 as output transformer and it can offer stable 24bit 192 kHz data for DAC. The I2S bus output of DigiPi module are only DATA, BCK, and LRCK signals via high-speed buffer gate IC, and the terminals of I2S output use RJ45 jack.

Note: The transmission line for I2S bus is different from network cable. The definition of transmission line must be depend on DigiPi module and own DAC.

[Module Test Result]

HW: Raspberry Pi 2B
OS: Volumio v1.55
I2S Driver: Hifiberry Digi
DAC: LKS Audio ES9018 DAC

	non-Resample (Recommend!)			Resample to 24bit/192kHz (Fastest Sinc Interpolator)			Resample to 24bit/192kHz (Medium Sinc Interpolator)
Sample Rate of source	COAX port	I2S port	%CPU of mpd	COAX port	I2S port	%CPU of mpd	COAX port	I2S port	%CPU of mpd
16bit/44.1kHz	OK	OK	1.5%	OK	OK	50%	Bad	Bad	100%
24bit/96kHz	OK	OK	4%	OK	OK	53%	Bad	Bad	100%

Note: When “%CPU of mpd” approaches 100%, the audio data may be incomplete.

[Compatibility]

This module is compatible with the Raspberry Pi model A+, B+ and 2B.

[Important note]

1. This module is a hand soldering product. Each module is during more than 24 hours continuous test for quality control and reliability.

2. This module contains Gold plated COAX which is soldered onto board (see figure 2).

3. The shipping list: 1pc DigiPi module, 4pcs M2.5x12mm spacers.