wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 20

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

WM9081
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In Software Control Mode, the WM9081 is controlled by writing to its control registers. Readback is
available for all registers, including device ID and power management status bits. The control
interface can operate as a 2-, 3- or 4-wire control interface: Readback is provided on the bi-
directional pin SDIN in 2-wire and 3-wire modes. The WM9081 Software Control interface is supplied
by the DBVDD power domain.
The available Software Control interface modes are summarised as follows:
2-wire mode is selected by setting the SCIM/CHANNEL pin to logic 0. When this pin is set to logic 1,
then 3-wire or 4-wire mode is selected according to the SPI_4WIRE register bit, as defined in Table
2.
In 4-wire mode, the electrical characteristics of the SDOUT pin are configurable using the SPI_CFG
register bit.
R40 (28h)
MW Slave 1
Table 2 Software Control Mode Configuration
2-WIRE CONTROL MODE
In 2-wire mode, the WM9081 is a slave device on the control interface; SCLK is a clock input, while
SDIN is a bi-directional data pin. To allow arbitration of multiple slaves (and/or multiple masters) on
the same interface, the WM9081 transmits logic 1 by tri-stating the SDIN pin, rather than pulling it
high. An external pull-up resistor is required to pull the SDIN line high so that the logic 1 can be
recognised by the master.
In order to allow many devices to share a single 2-wire control bus, every device on the bus has a
unique 7-bit device ID (this is not the same as the 8-bit address of each register in the WM9081).
The device ID is determined by the logic level on the ADDR0 and ADDR1 pins as shown in Table 3.
The LSB of the device ID is the Read/Write bit; this bit is set to logic 1 for “Read” and logic 0 for
“Write”.
Table 3 Control Interface Device ID Selection
The WM9081 operates as a slave device only. The controller indicates the start of data transfer with
a high to low transition on SDIN while SCLK remains high. This indicates that a device ID, register
address and data will follow. All devices on the 2-wire bus respond to the start condition and shift in
ADDRESS
2-wire mode uses pins SCLK and SDIN.
3-wire mode uses pins CS
4-wire mode uses pins CS
ADDR1
0
0
1
1
BIT
5
4
SPI_CFG
SPI_4WIRE
LABEL
¯ ¯ , SCLK and SDIN.
¯ ¯ , SCLK, SDIN and SDOUT.
DEFAULT
ADDR0
0
0
1
1
0
0
Controls the SDOUT pin in 4 wire mode
0 = SDOUT output is CMOS
1 = SDOUT output is open drain
Selects 3-wire or 4-wire mode
0 = 3-wire mode using bi-directional SDIN pin
1 = 4-wire mode using SDOUT
1101 1010 (DAh)
1101 1100 (DCh)
1101 1110 (DEh)
1101 1000 (D8h)
DESCRIPTION
DEVICE ID
PP, Rev 3.0, April 2009
Pre-Production
20