WM72016 – Secure F-RAM with Gen-2 RFID and Serial Port
DSPI write cycles are detailed in Figure 11 below. The host microcontroller drives all 4 DSPI signals for the
duration of the cycle. The WM72016 uses the rising edge of CLK to shift in the 2 data bits presented on the
D1 and D0 signals. The host microcontroller shall obey the timing constraints detailed in Table 7:. The host
microcontroller asserts the 2 data bits prior to the rising edge of CLK. The host microcontroller shifts the
instruction word with the first set of 8 CLK cycles and shifts the data word on the second set of 8 CLK cycles.
The write cycle is terminated by clearing the CS signal.
Figure 11. DSPI Write Cycle Detail
Table 7: AC Timing - DSPI Interface (2.0V<VDDR<3.6V, -40oC<TA<+85oC)
Parameter
Min
10ns
10ns
10ns
10ns
10ns
1.6µs
tCLK/2
Max
Description
tCSD
tCSH
tSU
tHD
tDD
-
Chip select setup to data assertion time.
Chip select hold time.
Data setup time.
-
tCLK/2 - 10ns
1/tCLK – 10ns
Data hold time.
Read data assert time.
Clock period.
TBD
tCLK
twd
-
-
Instruction to data word timing.
DSPI read cycles are detailed in Figure 12. The host microcontroller shall transmit the instruction word in the
same manner as done for DSPI write cycles. The WM72016 uses the rising edge of CLK to shift in the 2 data
bits presented on the D1 and D0 signals. Once the instruction word has been completely transmitted and the
CLK signal has been cleared to a logic zero, the host shall tri-state the D1 and D0 signals allowing the
WM72016 to drive the data bits for the remainder of the read cycle. The WM72016 shall shift a pair of data
bits on D1 and D0 on the rising edge of CLK – the host shall use the falling edge of CLK to capture the data
pair into its shift register. The host shall transmit a total of 8 CLK cycles to receive the entire data word, after
which it clears the CS to a logic zero to terminate the read cycle.
Figure 12. DSPI Read Cycle Detail
The syntax of the instruction word is detailed in Table 8: below.
Rev. 1.2
Sept. 2010
Page 13 of 21
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
