Production Data WM8737L
w
PD, Rev 4.4, January 2012
25
MASTER AND SLAVE MODE OPERATION
The WM8737L can be configured as either a master or slave mode device. As a master device the
WM8737L generates BCLK and ADCLRC and thus controls sequencing of the data transfer on
ADCDAT. In slave mode, the WM8737L 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 14). Master and slave modes
are illustrated below.
BCLK
ADCDAT
ADCLRC
WM8737
ADC
DSP /
ENCODER
BCLK
ADCDAT
ADCLRC
WM8737
ADC
DSP /
ENCODER
Figure 9a Master Mode Figure 9b Slave Mode
AUDIO DATA FORMATS
In Left Justified mode, the MSB is available on the first rising edge of BCLK following an ADCLRC
transition. The other bits up to the LSB are then transmitted in order. Depending on word length,
BCLK frequency and sample rate, there may be unused BCLK cycles before each ADCLRC
transition.
LEFT CHANNEL RIGHT CHANNEL
ADCLRC
BCLK
ADCDAT
1/fs
n321
n-2 n-1
LSBMSB
n321
n-2 n-1
LSBMSB
Figure 10 Left Justified Audio Interface (assuming n-bit word length)
In Right Justified mode, the LSB is available on the last rising edge of BCLK before an ADCLRC
transition. All other bits are transmitted before (MSB first). Depending on word length, BCLK
frequency and sample rate, there may be unused BCLK cycles after each ADCLRC transition.
LEFT CHANNEL RIGHT CHANNEL
ADCLRC
BCLK
ADCDAT
1/fs
n321
n-2 n-1
LSBMSB
n321
n-2 n-1
LSBMSB
Figure 11 Right Justified Audio Interface (assuming n-bit word length)
In I
2
S mode, the MSB is available on the second rising edge of BCLK following an ADCLRC
transition. The other bits up to the LSB are then transmitted in order. Depending on word length,
BCLK frequency and sample rate, there may be unused BCLK cycles between the LSB of one sample
and the MSB of the next.
