WM8731 / WM8731L
Production Data
The exact sample rates supported for all combinations are defined by the relationships in Table 22
below.
TARGET
ACTUAL SAMPLING RATE
SAMPLING
RATE
BOSR=0
BOSR=1
(272fs)
( 250fs)
kHz
kHz
kHz
8
8
8.021
12MHz/(250 x 48/8)
32
12MHz/(272 x 11/2)
not available
32
44.1
48
12MHz/(250 x 48/32)
not available
44.117
12MHz/272
48
not available
12MHz/250
88.2
96
not available
88.235
12MHz/136
96
not available
12MHz/125
Table 22 USB Mode Actual Sample Rates
ACTIVATING DSP AND DIGITAL AUDIO INTERFACE
To prevent any communication problems from arising across the Digital Audio Interface the Audio
Interface is disabled (tristate with weak 100k pulldown). Once the Audio Interface and the Sampling
Control has been programmed it is activated by setting the ACTIVE bit under Software Control.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
0001001
Active Control
0
ACTIVE
0
Activate Interface
1 = Active
0 = Inactive
Table 23 Activating DSP and Digital Audio Interface
It is recommended that between changing any content of Digital Audio Interface or Sampling Control
Register that the active bit is reset then set.
SOFTWARE CONTROL INTERFACE
The software control interface may be operated using either a 3-wire (SPI-compatible) or 2-wire MPU
interface. Selection of interface format is achieved by setting the state of the MODE pin.
In 3-wire mode, SDIN is used for the program data, SCLK is used to clock in the program data and
CSB is used to latch in the program data. In 2-wire mode, SDIN is used for serial data and SCLK is
used for the serial clock. In 2-wire mode, the state of CSB pin allows the user to select one of two
addresses.
SELECTION OF SERIAL CONTROL MODE
The serial control interface may be selected to operate in either 2 or 3-wire modes. This is achieved
by setting the state of the MODE pin.
MODE
INTERFACE
FORMAT
0
1
2 wire
3 wire
Table 24 Control Interface Mode Selection
PD, Rev 4.9, October 2012
45
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
