WM8945ECSSLASHR datasheet(101/169 Pages) WOLFSON

101 / 169 page

Production Data

WM8945

PD, May 2011, Rev 4.1

101

In Read operations (R/W=1), the SDA pin is driven by the controlling device to clock in the register

address, after which the WM8945 drives the SDA pin to output the applicable data bits.

Similarly to 2-wire control mode, the WM8945 can be set to transmit a logic 1 by tri-stating the SDA

pin, rather than pulling it high (SPI_OD = 1). An external pull-up resistor is required to pull the SDA

line high so that the logic 1 can be recognised by the master.

The 3-wire control mode timing is illustrated in Figure 45.

Figure 45 3-Wire Serial Control Interface

4-WIRE (SPI) CONTROL MODE

The 4-wire control interface uses the CS

¯¯ , SCLK, SDA and SDOUT pins.

The Data Output pin, SDOUT, can be configured as CMOS or Open Drain, as described in Table 66.

In CMOS mode, SDOUT is driven low when not outputting register data bits. In Open Drain mode,

SDOUT is undriven (high impedance) 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 WM8945.

The 4-wire control mode timing is illustrated in Figure 46 and Figure 47.

Figure 46 4-Wire Readback (CMOS)

WM8945ECS/R Datenblatt(PDF) 101 Page - Wolfson Microelectronics plc