SBE HW400c/2 User Manual

HighWire HW400c/2 User Reference Guide Rev 1.0

4.2.28 EEPROM Data Registers (EDR0 – EDR1)

The

y are used for holding

bac

ading EDR0-1. They are written to the EEPROM during a write operation.

ope

sign

EEPROM Data Registers are Read/Write registers. The

data bytes to be read from or written to the serial EEPROM.

Values written to EDR0-1 are stored in an internal shift register and cannot be read

k by re

Reading EDR0-1 returns serial data obtained from the most recent EEPROM ERD

ration.

All read/write operations are 2-bytes, since the EEPROM is organized in a x16
format. EDR0 is the least significant data byte (LSB) and EDR1 is the most

ificant data byte (MSB).

ble 58. EEPROM Data Registers (EDRn) Offset Address 0x2A-0x2B

eg ster Offset

Byte

EDR0 0x2A

LSB

EDR1 0x2B

MSB

4.3 Accessing the Serial EEPROM

with

4.3.1 Reading a

data is ready – proceed to the next step.

E. Read the data bytes from the EEPROM Data Registers EDR0 (LSB) and EDR1

for the register description.

The serial EEPROM (Atmel AT93C66A and other manufacturers) is organized
256 words of 2 bytes each. One word address is accessed per operation using the
CPLD state machine.

n EEPROM Address

A. Set to EEPROM Address

address.

B. Check the EBSY flag in the EEPROM Operation/Status Register (EOSR, see

Section 4.2.26). If set to “0”, proceed to the next step.

C. Write a “0x08” to the EOSR. This starts the read operation, which typically

takes 35 us to complete.

. Check the EBSY flag. If set to “0”, the

(MSB). See section 4.2.27

October 10, 2006

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