st72321j STMicroelectronics, st72321j Datasheet - Page 87

• Manufacturer Part Number: st72321j
• Description: 8-bit Mcu With Nested Interrupts, Flash, 10-bit Adc, 5 Timers, Spi, Sci, I2c Interface
• Manufacturer: STMicroelectronics

SERIAL PERIPHERAL INTERFACE (Cont’d)
10.5.3.1 Functional Description
A basic example of interconnections between a
single master and a single slave is illustrated in
Figure
The MOSI pins are connected together and the
MISO pins are connected together. In this way
data is transferred serially between master and
slave (most significant bit first).
The communication is always initiated by the mas-
ter. When the master device transmits data to a
slave device via MOSI pin, the slave device re-
Figure 52. Single Master/ Single Slave Application
52.
MSBit
8-BIT SHIFT REGISTER
GENERATOR
CLOCK
SPI
MASTER
LSBit
MOSI
SCK
SS
MISO
+5V
sponds by sending data to the master device via
the MISO pin. This implies full duplex communica-
tion with both data out and data in synchronized
with the same clock signal (which is provided by
the master device via the SCK pin).
To use a single data line, the MISO and MOSI pins
must be connected at each node ( in this case only
simplex communication is possible).
Four possible data/clock timing relationships may
be chosen (see
must be programmed with the same timing mode.
MISO
MOSI
SCK
SS
Figure
8-BIT SHIFT REGISTER
MSBit
Not used if SS is managed
by software
55) but master and slave
SLAVE
ST72321J
LSBit
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