WM8946 Datasheet, PDF (96/175 Pages) Wolfson Microelectronics plc – Stereo Low-Power CODEC with Video Buffer

WM8946
Production Data
CONTROL INTERFACE
The WM8946 is controlled by writing to its control registers. Readback is available for all registers.
The Control Interface can operate as either a 2-, 3- or 4-wire interface:
 2-wire (I2C) mode uses pins SCLK and SDA
 3-wire (SPI) mode uses pins C¯¯S, SCLK and SDA
 4-wire (SPI) mode uses pins C¯¯S, SCLK, SDA and SDOUT
Readback is provided on the bi-directional pin SDA in 2-/3-wire modes.
The device address in 2-wire (I2C) mode is 34h.
The WM8946 uses 15-bit register addresses and 16-bit data in all Control Interface modes.
SELECTION OF CONTROL INTERFACE MODE
The WM8946 Control Interface can be configured for I2C mode or SPI modes using the
CIFMODE/GPIO3 pin at power-up. The mode selection is as described in Table 63.
CIFMODE/GPIO3
INTERFACE FORMAT
Low
2 wire
High
3- or 4- wire
Table 62 Control Interface Mode Selection
After the Control Interface Mode has been configured, the MODE_GPIO register bit should be set in
order to latch the selection and to allow GPIO functions to be supported on the CIFMODE/GPIO3 pin.
After the MODE_GPIO register bit has been set, the Control Interface mode selection will remain
latched until a Software Reset or Power On Reset occurs. See “General Purpose Input / Output” for
details.
In 2-wire (I2C) Control Interface mode, Auto-Increment mode may be selected. This enables multiple
write and multiple read operations to be scheduled faster than is possible with single register
operations. The auto-increment option is enabled when the AUTO_INC register bit is set. This bit is
defined in Table 63. Auto-increment is disabled by default.
In SPI modes, 3-wire or 4-wire operation may be selected using the SPI_4WIRE register bit. In 3-wire
mode, register readback is provided using the bi-directional pin SDA. In 4-wire mode, register
readback is provided using SDOUT. The SDOUT pin may be configured as CMOS or as Open Drain
using the SPI_OD bit. In 3-wire mode the SDA pin may be configured as CMOS or as Open Drain
using the SPI_OD bit. If the open drain option is selected (SPI_OD = 1) then an external pull-up
resistor is required on the SDOUT or SDA output pin.
The Control Interface configuration bits are described in Table 63.
REGISTER
ADDRESS
t(14h)
Control
Interface
BIT
LABEL
2
SPI_OD
1
SPI_4WIRE
0
AUTO_INC
Table 63 Control Interface Configuration
DEFAULT
DESCRIPTION
0
SDOUT pin configuration
(applies to 3-wire and 4-wire mode
only)
0 = SDOUT output is CMOS
1 = SDOUT output is open drain
1
SPI control mode select
0 = 3-wire using bidirectional SDA
1 = 4-wire using SDOUT
0
Enables address auto-increment
(applies to 2-wire / I2C mode only)
0 = Disabled
1 = Enabled
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PD, July 2012, Rev 4.3
96