WM8351 Datasheet, PDF (43/330 Pages) Wolfson Microelectronics plc – Wolfson AudioPlus™ Stereo CODEC with Power Management

Production Data
WM8351
11.5 4-WIRE SERIAL CONTROL MODE
The 4-wire control interface uses the CSB, SCLK, SDATA and SDOUT pins, which are referenced to
the digital buffer supply, DBVDD. (In 4-wire mode, SDOUT is provided on GPIO6; CSB is provided on
GPIO7.)
4-wire control mode is selected by setting SPI_3WIRE = 1 and SPI_4WIRE = 1.
The Data Output pin, SDOUT, can be configured as CMOS or Open Drain, as described in Table 1. In
CMOS mode, SDOUT is driven low when not outputting register data bits. In Open Drain mode,
SDOUT is undriven when not outputting register data bits.
In Write operations (R/W=0), this mode is the same as 3-wire mode described above.
In Read operations (R/W=1), the SDATA pin is ignored following receipt of the valid register address.
SDOUT is driven by the WM8351.
The 4-wire control mode timing is illustrated in Figure 31 and Figure 32.
Figure 31 4-Wire Readback (CMOS)
Figure 32 4-Wire Readback (Open Drain)
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PD, April 2012, Rev 4.5
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