WM72016 – Secure F-RAM with Gen-2 RFID and Serial Port
The syntax for an unaddressed write command is shown in Figure 6 below. All protocol requirements
governing implementation of a WRITE command also apply to the UNADDR_WRITE command.
Figure 6. Unaddressed Write Syntax
Upon reception of a valid UNADDR_WRITE command, the WM72016 examines the state of the AUTOINCR
control bit:
AUTOINCR=0: The 16-bit data word cover-coded in the UNADDR_WRITE instruction is written to the
memory address stored in the Working Stored Address register. The contents of the Working Stored
Address register remain unaltered.
AUTOINCR=1: The Working Stored Address register is incremented by one, followed by the 16-bit data
word being written to memory. The contents of the Working Stored Address register will reflect the
memory address just written to. Figure 7 depicts 8 discrete unaddressed write cycles (REQRN command
for cover-coding not shown). Prior to the unaddressed write commands, the Working Stored Address has
a memory address of addrn. The first UNADDR_WRITE command with data payload write_data0 is
written to addrn+1; the second UNADDR_WRITE command with data payload write_data1 is written to
addrn+2, and so on. Upon completion of the final UNADDR_WRITE command, the memory pointer
contents of the Working Stored Address will be addrn+8, reflecting the memory address of the last
unaddressed write cycle. In this manner, the RFID interrogator does not have to read the memory
contents to discern the next available memory location. This substantially reduces the time required
in the RF field yielding greater throughput of a population of tags.
Figure 7. Unaddressed Write Cycles, AUTOINCR=1
The Working Stored Address pointer will be factory-initialized to the start of USER memory then
managed by the memory controller or the host application as required.
Rev. 1.2
Sept. 2010
Page 10 of 21
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
