Datasheet

DS2430A
6 of 19
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 always copies 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 and the validation key are issued, the data line must be held above V
PUPmin
for at least t
PROG
.
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 of the data to be read from the scratchpad. The DS2430A automatically
increments the address after every byte read by the master. After the data of address 1Fh has been read,
the address counter wraps 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.
NOT RECOMMENDED FOR NEW DESIGNS