W55P241

- 6 -

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

CLK

DI

DO

/CS

CLK

DO

DI

/CS

CLK

DI

DO

WAKEUP

Master

uC

WAKEUP

Slave 0

Slave 1

DIS

DIS

WAKEUP

“

0”

“

1”

SPI Control Interface

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

edge and after the last falling edge.