Production Data
WM8945
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
IM_TCHPD_INT
Interrupt mask for Touch Panel Pen
Down status
9
0
0 = Not masked
1 = Masked
IM_AUXADC_
INT
Interrupt mask for AUXADC Data
Ready status
8
0
0
0
0 = Not masked
1 = Masked
IM_LDO_UV_
INT
Interrupt mask for LDO
Undervoltage status
0 = Not masked
1 = Masked
Table 64 Interrupt Control
CONTROL INTERFACE
The WM8945 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 WM8945 uses 15-bit register addresses and 16-bit data in all Control Interface modes.
SELECTION OF CONTROL INTERFACE MODE
The WM8945 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 66.
CIFMODE/GPIO3
INTERFACE FORMAT
2 wire
Low
High
3- or 4- wire
Table 65 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 66. 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
PD, May 2011, Rev 4.1
97
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
