W55P241 Datasheet, PDF (6/32 Pages) List of Unclassifed Manufacturers – I/O device usable with many different microprocessors through SPI interface

W55P241
5.1.1 Physical Connection
The uC master may connect up to 2 slave devices as shown in the following figure. The W55P241
always operates in the slave mode. The master can be a microcontroller with 4 I/O pads or a dedicated
SPI H/W. Each time the master wants to talk to one of the slaves, bit6 of command byte must be
correctly specified. Slaves are identified by the DIS pad status. The master communicates with the
slave via 4 SPI pads. In addition to bit6 of command byte, /CS must be asserted (low active) for
W55P241 to receive the command. The W55P241 CLK runs on up to 10MHz. DI (master data output,
slave data input) and DO (master data input, slave data output) exchange data between the
microcontroller and the W55P241. To wake up the microcontroller, the WAKEUP or DO pad may
connect to its one additional wakeup-enabled pad.
/CS
Master ^CLK
uC _DO
WAKEUP ^DI
SPI Control Interface
/CS
DIS
CLK
Slave 0
DI
“0”
DO _WAKEUP
/CS ^WAKEUP
CLK
Slave 1
DI
DIS
DO
“1”
Figure 2 Connection of Master and Slave
5.1.2 Mode 0
Generally, the master’s dedicated SPI H/W (hardware) may support up to 4 SPI operation modes,
which are determined by the CLK’s idle state and phase (rising edge and falling edge). In the
W55P241, only mode 0 is supported. For both master and slave, data is transmitted on the falling edge
of CLK and data is received (sampled) on the rising edge of CLK. CLK keeps “0” before the 1^st rising
edge and after the last falling edge.
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