Digital Audio Output [13 & 14] - XMOS XS1-L2 Hardware Manual

USB Audio 2.0 Reference Design, XS1-L2 Edition Hardware Manual (1.6) 10/32
The reset input to the CODEC is mapped to bit 3 of port X1P4A on the XS1-L2.
The interrupt output from the CODEC is mapped to bit 3 of port X1P4B on the XS1-L2.
5.1 Analogue Audio I/O [4 - 12]
3.5mm Tip Ring Sleeve (TRS) audio jacks are provided for stereo audio inputs and
outputs. The layout of the audio jacks is shown in the connector diagram of the
board.
A simple passive AC-coupling and low pass filter circuit is used on input and output.
The circuit is configured such that the audio output will produce approximately
0.94V
capacitors, the output impedance falls with frequency and is approximately 1k
35Hz falling to 576
The input circuit contains an attenuator such that a 1.62V
produce a full scale digital output. The input impedance is approximately 9k .
The CODEC microphone and instrument inputs are AC-coupled to low noise op-amp
pre-amplifiers before being AC-coupled onto the CODEC inputs. These are set with
gains of -1 and -10 for the instrument and microphone inputs respectively.
A 3.5mm Tip Ring Sleeve (TRS) audio jack is provided for the stereo headphone out,
which is powered by a 75mW TI TPA152 stereo headphone amplifier. This is the a
capable of driving a minimum load of 32 . It is configured with a gain of -1.
6 Digital Audio Output [13 & 14]
Optical and coaxial digital audio transmitters are used to provide digital audio output
in formats such as IEC60958 consumer mode (S/PDIF) and ADAT. The signals are
generated from two 1-bit ports on the XS1-L2 as defined in the port map.
The data streams from the XS1-L2 are re-clocked using the external master clock
to synchronise the data into the audio clock domain. This is achieved using simple
external D-type flip-flops.
The optical output uses a TOSLINK optical connector with an integrated LED and
differential driving circuit. The coaxial output uses an RCA connector and is isolated
via a transformer.
Downloaded from Elcodis.com electronic components distributor
CODEC mode
Single speed
Double speed
Quad speed
(-0.54dBV) for a digital full scale signal. Due to the output coupling
@ 1kHz.
CODEC sample rate range
4-50kHz
50-100kHz
100-200kHz
www.xmos.com
@
(+4.2dBV) signal will