The Multi-Function Audio Kit (U-Series); Clocking And Clock Selection - XMOS xCORE-200 Multi-channel Audio board Design Manual

USB Audio Design Guide
6.3.2.4 Configuration 4
The same as Configuration 3 but with the CODEC set as I2S master. This configura-
tion can be made by making the changes for Configuration 3 and commenting out
the following line in customdefines.h :
//# define CODEC_SLAVE

6.4 The Multi-function Audio Kit (U-Series)

Provided is an application of the USB audio framework specifically for the hardware
described in
The application assumes a standard USB B socket (i.e. USB device) is attached as
the USB connectivity method.
The software design supports 2 channels channels of audio at sample frequencies
up to 192kHz and uses the following components:
XMOS USB Device Driver (XUD)
Endpoint 0
Endpoint buffer
Decoupler
Audio Driver
Device Firmware Upgrade (DFU)
S/PDIF Transmitter or MIDI
The software layout is the identical to the single tile L-Series Reference Design and
therefore the diagrams Figure
code running on the XS1-U chip.
As with the L-Series, each unit runs in a single core concurrently with the others
units. The lines show the communication between each functional unit.
Due to the MIPS requirement of the USB driver (see §3.14), only six cores can be
run on the single tile L-Series device so only one of S/PDIF transmit or MIDI can be
supported.

6.4.1 Clocking and Clock Selection

A single oscillator with a Phaselink PLL is used to generate fixed 24.576MHz and
22.5792MHz master-clocks.
This makes no change for the selection of master-clock in terms of software
interaction: A single pin is (bit 1 of port 32A) is used to select between the two
master-clock frequencies.
XM0088546.1
§2.3 and is implemented on the U-Series single tile device (500MIPS).
32
1
and Figure 33 show the software layout of the
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