PCM4104PFBTG4 Datasheet, PDF (25/40 Pages) Texas Instruments –
High-Performance, 24-Bit,216kHz Sampling

PCM4104
www.ti.com
SERIAL PERIPHERAL INTERFACE (SPI) PORT
OPERATION
The SPI port is a four-wire synchronous serial interface
that is used to access the on-chip control registers when
the PCM4104 is configured for Software mode operation.
The CDIN input (pin 23) is the serial data input for the port,
while CDOUT (pin 24) is used for reading back control
register contents in a serial fashion. The CS input (pin 21)
functions as the chip select input, and must be forced low
for register write or read access. The CCLK input (pin 22)
functions as the serial data clock, used to clock data in and
out of the port. Data is clocked into the port on the rising
edge of CCLK, while data is clocked out of the port on the
falling edge of CCLK.
There are three modes of operation supported for the SPI
port: Single Register, Continuous, and Auto-Increment.
The Single Register and Continuous modes are similar to
one another. In Continuous mode, instead of bringing the
CS input high after writing or reading a single register, the
CS input is held low and a new control byte is issued with
a new address for the next write or read operation.
Continuous mode allows multiple, sequential or
nonsequential register addresses to be read or written in
succession, as shown in Figure 16.
Auto-Increment mode is designed for writing or reading
multiple sequential register addresses. After the first
register is written or read, the register address is
SBAS291C − AUGUST 2003 − REVISED DECEMBER 2004
automatically incremented by 1, so the next write or read
operation is performed without issuing another control
byte, as shown in Figure 17.
Control Byte (or Byte 0)
The control byte, or byte 0, is the first byte written to the
PCM4104 SPI port when performing a write or read
operation. The control byte includes bits that define the
operation to be performed (read or write), the
auto-increment mode status, and the control register
address.
The Read/Write bit, R/W, is set to 0 to indicate a register
write operation, or set to 1 for a register read operation.
The Increment bit, INC, enables or disables the
Auto-Increment mode of operation. When this bit is set to
a 0, auto-increment operation is disabled, and the
operation performed is either Single Register or
Continuous. Setting the INC bit to 1 enables
Auto-Increment operation.
A two-bit key code, 10_B, follows the INC bit and must be
present in order for any operation to take place on the
control port. Any other combination for these bits will result
in the port ignoring the write or read request.
The four-bit address field, A[3:0], is used to specify the
control register address for the read or write operation, or
the starting address for an Auto-Increment write or read
operation.
Set CS = 1 here for Single Register Operations
Keep CS = 0 for writing or reading multiple registers in Continuous mode
CS
CDIN
CDOUT
Control Byte
byte 0
High Impedance
Register Data
byte 1
Register Data
byte 1
Control Byte
byte 0
High Impedance
Register Data
byte 1
Register Data
byte 2
byte N
byte N
CCLK
Control Byte Definition (Byte 0)
MSB
R/W INC 1
LSB
0 A3 A2 A1 A0
Register Address
Auto −Increment Control: Set to 0 for Single Register or Continuous Operation
Read/WriteControl: 0 = Write
1 = Read
Figure 16. Single Register and Continuous Write or Read Operation
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