CDCE62002 SPI Command Structure

CDCE62002

The CDCE62002 supports four commands issued by the Master via the SPI:

•

Write to RAM

•

Read Command

•

Copy RAM to EEPROM – unlock

•

Copy RAM to EEPROM – lock

Table 6 provides a summary of the CDCE62002 SPI command structure. The host (master) constructs a Write to

RAM command by specifying the appropriate register address in the address field and appends this value to the

beginning of the data field. Therefore, a valid command stream must include 32 bits, transmitted LSB first. The

host must issue a Read Command to initiate a data transfer from the CDCE62002 back to the host. This

command specifies the address of the register of interest in the data field.

Table 6. CDCE62002 SPI Command Structure

Data Field (28 Bits)

Addr Field

(4 BIts)

2

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

1

1

Register

Operation

NVM

7

6

5

4

3

2

1

0

9

8

7

6

5

4

3

2

1

0

9

8

7

6

5

4

3

2

1

0

3

2

1

0

0

Write to RAM

Yes

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

0

0

0

0

1

Write to RAM

Yes

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

0

0

0

1

2

Status/Control

No

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

0

0

1

0

Instruction

Read Command

No

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

A

A

A

A

1

1

1

0

Instruction

RAM EEPROM

Unlock

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

1

1

1

1

Instruction

RAM EEPROM

Lock

(1)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

1

0

0

0

0

0

0

0

1

1

1

1

1

1

(1)

CAUTION: After execution of this command, the EEPROM is permanently locked. After locking the EEPROM, device configuration can

only be changed via Write to RAM after power-up; however, the EEPROM can no longer be changed.

20

Submit Documentation Feedback

Copyright © 2009, Texas Instruments Incorporated

Product Folder Link(s): CDCE62002