WM8750L
Production Data
DIGITAL AUDIO INTERFACE
The digital audio interface is used for inputting DAC data into the WM8750L and outputting ADC data
from it. It uses five pins:
ADCDAT: ADC data output
ADCLRC: ADC data alignment clock
DACDAT: DAC data input
DACLRC: DAC data alignment clock
BCLK: Bit clock, for synchronisation
The clock signals BCLK, ADCLRC and DACLRC can be outputs when the WM8750L operates as a
master, or inputs when it is a slave (see Master and Slave Mode Operation, below).
Four different audio data formats are supported:
Left justified
Right justified
I2S
DSP mode
All four of these modes are MSB first. They are described in Audio Data Formats, below. Refer to the
Electrical Characteristic section for timing information.
MASTER AND SLAVE MODE OPERATION
The WM8750L can be configured as either a master or slave mode device. As a master device the
WM8750L generates BCLK, ADCLRC and DACLRC and thus controls sequencing of the data
transfer on ADCDAT and DACDAT. In slave mode, the WM8750L responds with data to clocks it
receives over the digital audio interface. The mode can be selected by writing to the MS bit (see
Table 23). Master and slave modes are illustrated below.
BCLK
ADCLRC
DACLRC
ADCDAT
DACDAT
BCLK
ADCLRC
DACLRC
ADCDAT
DACDAT
DSP
ENCODER/
DECODER
DSP
ENCODER/
DECODER
WM8750
CODEC
WM8750
CODEC
Note: The ADC and DAC can run at different sample rates
Note: The ADC and DAC can run at different sample rates
Figure 16 Master Mode
Figure 17 Slave Mode
Note: For optimum ADC audio performance in Slave Mode, the BCLK input signal edge should
coincide with the falling edge of MCLK.
Note that the ADCDAT output pin may be either logic ‘1’ or logic ‘0’ at power-up until data is clocked
out from the ADC. It is recommended to ensure that any external connection to the ADCDAT pin is
compatible with the ADCDAT output pin being driven either high or low by the WM8750L until ADC
data is clocked out. Alternatively, the ADCDAT pin can be tri-stated by setting the TRI bit in Register
R24 (see Table 35).
PD, Rev 4.4, August 2012
40
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
