wm8918 Wolfson Microelectronics plc, wm8918 Datasheet - Page 41

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

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The digital microphone interface requires that MIC1 (Left Channel) transmits a data bit each time that
DMICCLK is high, and MIC2 (Right Channel) transmits when DMICCLK is low. The WM8918
samples the digital microphone data in the middle of each DMICCLK clock phase. Each microphone
must tri-state its data output when the other microphone is transmitting.
Figure 28 Digital Microphone Interface Timing
The digital microphone interface control fields are described in Table 8.
Table 8 Digital Microphone Interface Control
Note that all the GPIO pins are referenced to the DBVDD power domain; the IN1L and IN1R pins are
referenced to the AVDD power domain. Care must be taken to ensure the microphone logic levels
are compatible with the applicable power domain.
R10 (0Ah)
Analogue DMIC
0
R18 (12h)
Power
Management
(6)
R39 (27h)
Digital
Microphone 0
REGISTER
ADDRESS
BIT
12
11
0
1
0
DMIC_OSR12
8
DMICR_ENA
DMICL_ENA
DMIC_ENA
DMIC_SRC
LABEL
DEFAULT
1
0
0
0
0
Digital Microphone DSP Enable
0 = Disabled
1 = Enabled
Digital Microphone mode
0 = Disabled
1 = Audio DSP input is from digital
microphone interface
When DMIC_ENA = 0, the Digital
microphone clock (DMICCLK) is held
low.
Selects Digital Microphone Data Input
pin
0 = IN1L/DMICDAT1
1 = IN1R/DMICDAT2
DMIC Oversampling Ratio
0 = Normal (64 x fs)
1 = Reserved
This bit must be set to 0 for digital
microphone operation.
Digital Microphone DSP Enable
0 = Disabled
1 = Enabled
PD, Rev 4.0, September 2010
DESCRIPTION
WM8918
41