DS2430A

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102199

MEMORY FUNCTION FLOW CHART Figure 6

COPY SCRATCHPAD [55h]

After the data stored in the scratchpad has been verified the master may send the Copy Scratchpad

command followed by a validation key of A5h to transfer data from the scratchpad to the EEPROM

memory. This command will always copy the data of the entire scratchpad. Therefore, if one desires to

change only a few bytes of the EEPROM data, the scratchpad should contain a copy of the latest

EEPROM data before the Write Scratchpad and Copy Scratchpad commands are issued. After this

command is issued, the data line must be held at logic high level for at least 10 ms.

READ MEMORY [F0h]

The Read Memory command is used to read a portion or all of the EEPROM data memory and to copy

the entire data memory into the scratchpad to prepare for changing a few bytes. To copy data from the

data memory to the scratchpad and to read it, the master must issue the read memory command followed

by the 1-byte starting address from where data is to be read from the scratchpad. The DS2430A will

automatically increment the address after every byte read by the master. After the data of address 1Fh has

been read, the address counter will wrap around to 00h for the next byte and reading continues until the

master sends a reset pulse. If one intends to copy the entire data memory to the scratchpad without

reading data, a starting address is not required; the master may send a reset pulse immediately following

the command code.