wm8918 Wolfson Microelectronics plc, wm8918 Datasheet - Page 92

• Manufacturer Part Number: wm8918
• Description: Ultra Low Power Dac For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

WM8918
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LOOPBACK
Setting the LOOPBACK register bit enables digital loopback. When this bit is set, the DMIC digital
data output is routed to the DAC digital data input path. The digital audio interface input (AIFRXDAT)
is not used when LOOPBACK is enabled.
Table 55 Loopback Control
Note: When the digital sidetone is enabled, DMIC data will also be added to DAC digital data input
path within the Digital Mixing circuit. This applies regardless of whether LOOPBACK is enabled.
DIGITAL PULL-UP AND PULL-DOWN
The WM8918 provides integrated pull-up and pull-down resistors on each of the MCLK, AIFRXDAT,
LRCLK and BCLK pins. This provides a flexible capability for interfacing with other devices. Each of
the pull-up and pull-down resistors can be configured independently using the register bits described
in Table 56.
Table 56 Digital Audio Interface Pull-Up and Pull-Down Control
R24 (18h)
Audio
Interface 0
R126 (7Eh)
Digital Pulls
REGISTER
REGISTER
ADDRESS
ADDRESS
BIT
BIT
8
7
6
5
4
3
2
1
0
AIFRXDAT_P
AIFRXDAT_P
LOOPBACK
LRCLK_PU
LRCLK_PD
MCLK_PU
MCLK_PD
BCLK_PU
BCLK_PD
LABEL
LABEL
U
D
DEFAULT
DEFAULT
0
0
0
0
0
0
0
0
0
Digital Loopback Function
0 = No loopback
1 = Loopback enabled (DMIC data
output is directly input to DAC data
input).
MCLK pull-up resistor enable
0 = pull-up disabled
1 = pull-up enabled
MCLK pull-down resistor enable
0 = pull-down disabled
1 = pull-down enabled
AIFRXDAT pull-up resistor enable
0 = pull-up disabled
1 = pull-up enabled
AIFRXDAT pull-down resistor enable
0 = pull-down disabled
1 = pull-down enabled
LRCLK pull-up resistor enable
0 = pull-up disabled
1 = pull-up enabled
LRCLK pull-down resistor enable
0 = pull-down disabled
1 = pull-down enabled
BCLK pull-up resistor enable
0 = pull-up disabled
1 = pull-up enabled
BCLK pull-down resistor enable
0 = pull-down disabled
1 = pull-down enabled
PD, Rev 4.0, September 2010
DESCRIPTION
DESCRIPTION
Production Data
92