Rainbow Electronics DS2422 - Manual (Page 6)

DS2422/DS2423
6 of 25
Read Scratchpad Command [AAH]
This command is used to verify scratchpad data and target address. After issuing the Read Scratchpad
command, the master begins reading. The first 2 bytes will be the target address. The next byte will be the
ending offset/data status byte (E/S) followed by the scratchpad data beginning at the byte offset (T4: T0).
The master may read data until the end of the scratchpad after which the data read will be all logic 1s.
Copy Scratchpad [5AH]
This command is used to copy data from the scratchpad to memory. After issuing the Copy Scratchpad
command, the master must provide a 3-byte authorization pattern which can be obtained by reading the
scratchpad for verification. This pattern must exactly match the data contained in the three address
registers (TA1, TA2, E/S, in that order). If the pattern matches, the AA (Authorization Accepted) flag
will be set and the copy will begin. A pattern of alternating 1s and 0s will be transmitted after the data has
been copied until a Reset Pulse is issued by the master. Any attempt to reset the part will be ignored while
the copy is in progress. Copy typically takes 30µs. The data to be copied is determined by the three
address registers. The scratchpad data from the beginning offset through the ending offset will be copied
to memory, starting at the target address. Anywhere from 1 to 32 bytes may be copied to memory with
this command. The AA flag will be cleared only by executing a Write Scratchpad command.