CS4630 datasheet(23/38 Pages) CIRRUS

23 / 38 page

CS4630

DS445PP1

7. EEPROM INTERFACE

The EEPROM configuration interface allows the

connection of an optional external EEPROM de-

vice to provide power-up configuration informa-

tion. The external EEPROM is not required for

proper operation; however, in some applications

power-up configuration settings other than the de-

fault values may be required to support specific op-

erating system compatibility requirements.

After a hardware reset, an internal state machine in

the CS4630 will automatically detect the presence

of an external EEPROM device (assuming EEPDIS

is low) and load the Subsystem ID and Subsystem

Vendor ID fields, along with two bytes of general

configuration information, into internal registers.

At power-up, the CS4630 will attempt to read from

the external device, and will check the data re-

ceived from the device for a valid signature header.

If the header data is invalid, the data transfer is

aborted. After power-up, the host can read or write

from/to the EEPROM device by accessing specific

registers in the CS4630. Cirrus Logic provides soft-

ware to read and write the EEPROM.

The two-wire interface for the optional external

EEPROM device is depicted in Figure 14. During

data transfers, the data line (EEDAT) can change

state only while the clock signal (EECLK) is low.

A state change of the data line while the clock sig-

nal is high indicates a start or stop condition to the

EEPROM device.

The EEPROM device read access sequence is

shown in the Figure 15. The timing follows that of

a random read sequence. The CS4630 first per-

forms a “dummy” write operation, then generates a

start condition followed by the slave device address

and the byte address of zero. The CS4630 always

begins access at byte address zero and continues

access a byte at a time, using a sequential read, until

all needed bytes in the EEPROM are read. Since

only a maximum of 12 bytes are needed, the small-

est EEPROM available will suffice.

SLIMD SP

Core

EEDAT

EECLK

4.7 k

Ω

2-wire

Serial

EEPROM

Figure 14. External EEPROM Connection

S 1 0 1 0 0 000 A 0 0 0000 0 0 A S 10 10 00 01 A

Data

Start

Part

Address

Start

Acknowledge

Stop

Acknowledge

Data

EEPROM

Write

Read

Bank

Address

Part

Address

CS46XX

Figure 15. EEPROM Read Sequence

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