Programming Cycle of Six Words and Programming Into EEPROM Example

EnterProgrammingSequence

Word0

Payload

Word1

Payload

Word5

Payload

StateMachineJump

State2

State3

®

StateMachineJump

State3

State1

®

Aftereightbits,thepayloaddata

aretransferredtotheRAM

andbecomeactive

Waitforatleast10ms

beforeexitingtheEEPROMwritephase

forsaveoperation

Enter Register Readback Mode

1

1

1

1

1

0

0

1

2

56

57

58

OutputOscillation

OutputOscillation

EnterReadbackSequence

60thfallingedge

switchesbackinto

normaloperation

EEPROMcontent:firstbitavailable

afterfirstfallingedge

FetchEEPROM

contentwith

firstCLK

SDATA

FOUT

CDCE421A

Figure 3 shows an Enter Programming Mode sequence and how the different words can be written. The

addressing of Word0 … Word5 can be seen in bold. After that, the inverted payload for the respective word is

clocked in. In this example, this step is followed by a Jump from State 2

→State 3 into Enter EEPROM

programming with EEPROM lock. In the EEPROM programming state, it is required to wait at least 10ms for

save programming to occur. The last command is a jump from State 3 back to State 1 (normal operation). Then

cycle the power and verify that the device is functioning as programmed.

Figure 3. Programming Cycle of Six Words and Programming Into EEPROM

Similar to the Enter Programming Mode sequence, the Enter Register Readback Mode is written into SDATA.

After the command has been issued, the SDATA-input is reconfigured as the clock input. By applying one clock,

the EEPROM content is read into the shift registers. Then, by applying further clocks at SDATA, the EEPROM

content can be clocked out and observed at FOUT. Additionally, FOUT is reconfigured during this operation, as

can be seen in Figure 4. There are 59 bits to be clocked out. With the 61st rising clock edge, the FOUR pin is

reconfigured for normal operation.

Figure 4. Register Readback Mode Timing Sequence

Copyright © 2009, Texas Instruments Incorporated

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