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System Reset Control

Mode Register Reset Control

SPI SERIAL CONTROL PORT FOR MODE CONTROL (PCM1850A)

MSB

0

IDX6

IDX5

IDX4

IDX3

IDX2

IDX1

IDX0

D7

D6

D5

D4

D3

D2

D1

D0

0

0

LSB

Register Index (or Address)

Register Data

R0001-01

IDX0

D7

D6

D4

D5

D3

D2

D1

D0

MS

MC

MD

IDX1

IDX2

IDX3

IDX4

IDX5

IDX6

0

X

X

X

0

IDX6

T0048-04

PCM1850A

PCM1851A

SLES173 – MARCH 2006

The system reset control is used to resynchronize the system via the serial port when the system clock

frequency, interface mode, and data format are changed. Change them while SRST = LOW. If they are changed

during normal operation, analog performance can be degraded.

SRST

SYSTEM RESET

0

Resynchronization

1

Normal operation (default)

The MRST bit is used to reset the mode control register to its default settings via the serial port.

MRST

MODE REGISTER RESET

0

Set default value

1

Normal operation (default)

The user-programmable built-in functions of the PCM1850A can be controlled through a serial control port with

the SPI format. All operations for the serial control port use 16-bit data words. Figure 27 shows the control data

word format. The most-significant bit must be set to 0. Seven bits, labeled IDX[6:0], set the register index (or

address) for write operations. The least-significant eight bits, D[7:0], contain the data to be written to the register

specified by IDX[6:0].

Figure 28 shows the functional timing diagram for writing to the serial control port. MS (pin 30) is held at a logic-1

state until a register needs to be written. To start the register write cycle, MS is set to logic-0. Sixteen clocks are

then provided on MC (pin 31), corresponding to the 16 bits of the control data word on MD (pin 32). After the

sixteenth clock cycle has completed, the data is latched into the indexed mode control register in the write

operation. To write the next data word, MS must be set to 1 once.

Figure 27. Control Data Word Format for MD

Figure 28. Serial Control Format

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