AD9548SLASHPCBZ datasheet(50/112 Pages) AD

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AD9548

Rev. 0 | Page 50 of 112

Table 27. EEPROM Conditional Processing Example

Instruction

Action

0x08

Transfer the system clock register contents

regardless of the current condition.

0x01

0x00

0xB1

Tag Condition 1

0x19

Transfer the clock distribution register contents

only if condition = 1

0x04

0x00

0xB2

Tag Condition 2

0xB3

Tag Condition 3

0x07

Transfer the reference input register contents only

if condition = 1, 2, or 3

0x05

0x00

0x0A

Calibrate the system clock only if condition = 1, 2,

or 3

0xB0

Clear the condition tag board

0x80

Execute an I/O update regardless of the value of

the condition

0x0A

Calibrate the system clock regardless of the value

of the condition

Storing Multiple Device Setups in EEPROM

Conditional processing makes it possible to create a number of

different device setups, store them in EEPROM, and download

a specific setup on demand. To do so, first program the device

control registers for a specific setup. Then, store an upload

sequence in the EEPROM scratch pad with the following

general form:

Condition instruction (B1 to CF) to identify the setup with

a specific condition (1 to 31)

Data instructions (to save the register contents) along with

any required calibrate and/or I/O update instructions

Pause instruction (FE)

With the upload sequence written to the scratch pad, perform

an EEPROM upload (Register 0E02, Bit 0).

Reprogram the device control registers for the next desired

setup. Then store a new upload sequence in the EEPROM

scratch pad with the following general form:

Condition instruction (B0)

The next desired condition instruction (B1 to CF, but

different than the one used during the previous upload to

identify a new setup)

Data instructions (to save the register contents) along with

any required calibrate and/or I/O update instructions

Pause instruction (FE)

With the upload sequence written to the scratch pad, perform

an EEPROM upload (Register 0E02, Bit 0).

Repeat the process of programming the device control registers

for a new setup, storing a new upload sequence in the EEPROM

scratch pad (Step 1 through Step 4), and executing an EEPROM

upload (Register 0E02, Bit 0) until all of the desired setups have

been uploaded to the EEPROM.

Note that, on the final upload sequence stored in the scratch

pad, the pause instruction (FE) must be replaced with an end

instruction (FF).

To download a specific setup on demand, first store the

condition associated with the desired setup in Register 0E01,

Bits[4:0]. Then perform an EEPROM download (Register 0E03,

Bit 1). Alternatively, to download a specific setup at power-up,

apply the required logic levels necessary to encode the desired

condition on the M3 to M7 multifunction pins. Then power up

the device; an automatic EEPROM download occurs. The

condition (as established by the M3 to M7 multifunction pins)

guides the download sequence and results in a specific setup.

Keep in mind that the number of setups that can be stored

in the EEPROM is limited. The EEPROM can hold a total of

2048 bytes. Each nondata instruction requires one byte of

storage. Each data instruction, however, requires N + 4 bytes of

storage, where N is the number of transferred register bytes and

the other four bytes include the data instruction itself (one

byte), the target address (two bytes), and the checksum

calculated by the EEPROM controller during the upload

sequence (one byte).

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