ST92124V1Q-Auto STMicroelectronics, ST92124V1Q-Auto Datasheet - Page 252

• Manufacturer Part Number: ST92124V1Q-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST92124V1Q-Auto

• Internal Memory: Single Voltage FLASH up to 256 Kbytes, RAM up to 8Kbytes, 1K byte E3 TM (Emulated EEPROM)
• Minimum Instruction Time: 83 ns (24 MHz int. clock)

ST92124xxx-Auto/150xxxxx-Auto/250xxxx-Auto
SERIAL PERIPHERAL INTERFACE (Cont’d)
10.7.4 Functional Description
Figure 121
(SPI) block diagram.
This interface contains 4 dedicated registers:
Refer to the SPCR, SPPR, SPSR and SPDR reg-
isters in
10.7.4.1 Master Configuration
In a master configuration, the serial clock is gener-
ated on the SCK pin.
Procedure
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– A Control Register (SPCR)
– A Prescaler Register (SPPR)
– A Status Register (SPSR)
– A Data Register (SPDR)
– Define the serial clock baud rate by setting/re-
– Select the CPOL and CPHA bits to define one
– The SS pin must be connected to a high level
– The MSTR and SPOE bits must be set (they
setting the DIV2 bit of SPPR register, by writ-
ing a prescaler value in the SPPR register and
programming the SPR0 & SPR1 bits in the
SPCR register.
of the four relationships between the data
transfer and the serial clock (see
signal during the complete byte transmit se-
quence.
remain set only if the SS pin is connected to a
high level signal).
Section
shows the serial peripheral interface
10.7.6for the bit definitions.
Figure
123).
In this configuration the MOSI pin is a data output
and the MISO pin is a data input.
Transmit Sequence
The transmit sequence begins when a byte is writ-
ten the SPDR register.
The data byte is parallel loaded into the 8-bit shift
register (from the internal bus) during a write cycle
and then shifted out serially to the MOSI pin most
significant bit first.
When data transfer is complete:
During the last clock cycle the SPIF bit is set, a
copy of the data byte received in the shift register
is moved to a buffer. When the SPDR register is
read, the SPI peripheral returns this buffered val-
ue.
Clearing the SPIF bit is performed by the following
software sequence:
1. An access to the SPSR register while the SPIF
2. A read of the SPDR register.
Note: While the SPIF bit is set, all writes to the
SPDR register are inhibited until the SPSR regis-
ter is read.
– The SPIF bit is set by hardware
– An interrupt is generated if the SPIS and SPIE
bit is set
bits are set.