Digital Audio Output - XMOS XK-AUDIO-316-MC-AB Hardware Manual

Board Net
X_DAC_D0
X_DAC_D1
X_DAC_D2
X_DAC_D3
DAC_MUTE_N
LRCK
Figure 9:
BCLK
Analog output
xCORE GPIO
MCLK_DAC

8 Digital audio output

Optical and coaxial digital audio outputs are provided. Both of these outputs can support
transmission of audio data in IEC60958 consumer mode (S/PDIF) format. This format
allows transmission of two channels of audio data at up to 192kHz. Note the optical
transmitter used on the board can only support up to 96kHz in this mode.
Additionally the optical output can transmit data in the ADAT optical format. This format
allows transmission of eight channels of audio data at 48kHz. The S/MUX extension to
ADAT allows four channels at 96kHz or two channels at 192kHz.
In order to reduce clock jitter on these outputs, the data outputs from xcore.ai are re-
clocked using the global audio master clock to synchronise the data into the audio clock
domain. This is achieved using simple external D-type flip-flops.
Figure 10:
Digital audio
output
The signals are generated from two 1-bit ports on xcore.ai.
9
xcore.ai Multichannel Audio Board 1v1 Hardware Manual
xCORE GPIO Port
X1D39 P1P0
X1D38 P1O0
X1D37 P1N0
X1D36 P1M0
X0D16 P4D0
X1D01 P1B0
X1D10 P1C0
See note NA
Description
Serial data output 0 (I2S or TDM)
Serial data output 1 (I2S or TDM)
Serial data output 2 (I2S or TDM)
Serial data output 3 (I2S or TDM)
Output to mute audio when low
Serial left/right frame clock
Bit clock for serial data transfer
Buffered global audio master clock