AD9544SLASHPCBZ datasheet(53/62 Pages) AD

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Data Sheet

AD9544

Rev. 0 | Page 53 of 62

Instructions with a hexadecimal value from 0x00 through 0x7F

indicate a register transfer operation. Register transfer instructions

require a 2-byte suffix, which constitutes the starting address of

the AD9544 register targeted for transfer (where the first byte

to follow the data instruction is the most significant byte of the

data instruction, it knows to interpret the next two bytes as the

Note that the value of the register transfer instruction encodes

the payload length (number of bytes). That is, the EEPROM

controller knows how many register bytes to transfer to/from

the indicated register by adding 1 to the instruction value. For

example, Data Instruction 0x1A has a decimal value of 26;

therefore, the controller knows to transfer 27 bytes to and from

the target register (that is, one more than the value of the

instruction).

Input/Output Update Instruction (0x80)

When the EEPROM controller encounters an input/output

update instruction during an upload sequence, it stores the

instruction in EEPROM. When encountered during a download

sequence, however, the EEPROM controller initiates an

input/output update event (equivalent to the user asserting the

IO_UPDATE bit in the serial port section of the register map).

Device Action Instructions (0x90 to 0xAF)

When the EEPROM controller encounters a device action

instruction during an upload sequence, it stores the instruction

in EEPROM. When encountered during a download sequence,

however, the EEPROM controller executes the specified action

per Table 31.

Conditional Instructions (0xB0 to 0xBF)

The conditional instructions allow conditional execution of

EEPROM instructions during a download sequence. During an

upload sequence, however, they are stored as is and have no

effect on the upload process.

Conditional processing makes use of four elements:

•

The conditional instruction.

•

The condition value.

•

The condition ID.

•

The condition map.

Conditional Instruction

When the EEPROM controller encounters a conditional

instruction during an upload sequence, it stores the instruction

in the EEPROM. When the EEPROM controller detects a

conditional instruction during a download sequence, it affects

the condition map as well as the outcome of conditional processing.

Condition Value

The condition value has a one to one correspondence to the

conditional instruction. Specifically, the condition value is the

value of the conditional instruction minus 0xB0. Therefore,

condition values have a range of 0 to 15. The EEPROM controller

uses condition values in conjunction with the condition map,

while the user uses a condition value to populate the EEPROM

load condition bit field of the register map with a condition ID.

Condition ID

The condition ID is the value stored in the 4-bit EEPROM load

condition bit field in the EEPROM section of the register map.

The EEPROM controller uses the condition ID in conjunction

with the condition map to determine which instructions to

execute or ignore during a download sequence.

Condition Map

The condition map is a table maintained by the EEPROM

controller consisting of a list of condition values. When the

EEPROM controller encounters a conditional instruction

during a download sequence, it determines the corresponding

condition value of the instruction (0 to 15). If the condition

value is nonzero, the EEPROM controller places the condition

value in the condition map. Conversely, if the condition value

is zero, the controller clears the condition map and applies

Condition 0. Condition 0 causes all subsequent instructions to

execute unconditionally (until the controller encounters a new

conditional instruction that causes conditional processing).

Conditional Processing

While executing a download sequence, the EEPROM controller

executes or skips instructions depending on the condition ID

and the contents of the condition map (except for the condi-

tional and end of data instructions, which always execute

unconditionally).

If the condition map is empty or the condition ID is zero, all

instructions execute unconditionally during download. However,

if the condition ID is nonzero and the condition map contains a

condition value matching the condition ID, the EEPROM

controller executes the subsequent instructions. Alternatively,

if the condition ID is nonzero but the condition map does not

contain a condition value matching the condition ID, the

EEPROM controller skips instructions until it encounters a

conditional instruction with a condition value of zero or a

condition value matching the condition ID.

Note that the condition map allows multiple conditions to exist

at any given moment. This multiconditional processing mecha-

nism enables the user to have one download instruction sequence

with many possible outcomes, depending on the value of the

condition ID and the order in which the controller encounters

conditional instructions. An example of the use of conditional

processing is shown in Table 32.

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