MC812A4CPVE8 Freescale Semiconductor, MC812A4CPVE8 Datasheet - Page 182

• Manufacturer Part Number: MC812A4CPVE8
• Description: IC MCU 16BIT EEPROM 4K 112-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC12r

Specifications of MC812A4CPVE8

• Core Processor: CPU12
• Core Size: 16-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: POR, WDT
• Number Of I /o: 83
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: EEPROM
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 112-LQFP
• Processor Series: HC812A
• Core: HC12
• Data Bus Width: 16 bit
• Data Ram Size: 1 KB
• Interface Type: SCI, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 91
• Number Of Timers: 8
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit, 8 Channel
• Controller Family/series: 68HC12
• No. Of I/o's: 91
• Eeprom Memory Size: 4KB
• Ram Memory Size: 1KB
• Cpu Speed: 8MHz
• No. Of Timers: 1
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

Serial Peripheral Interface (SPI)
15.5 Functional Description
The SPI allows full-duplex, synchronous, serial communication between the MCU and peripheral devices,
including other MCUs. In master mode, the SPI generates the synchronizing clock and initiates
transmissions. In slave mode, the SPI depends on a master peripheral to start and synchronize
transmissions.
15.5.1 Master Mode
The SPI operates in master mode when the master mode bit, MSTR, is set.
Only a master SPI module can initiate transmissions. Begin the transmission from a master SPI module
by writing to the SPI data register. If the shift register is empty, the byte immediately transfers to the shift
register. The byte begins shifting out on the master out, slave in pin (MOSI) under the control of the serial
clock. See
As the byte shifts out on the MOSI pin, a byte shifts in from the slave on the master in, slave out pin (MISO)
pin. On the eighth serial clock cycle, the transmission ends and sets the SPI flag, SPIF. At the same time
that SPIF becomes set, the byte from the slave transfers from the shift register to the SPI data register.
The byte remains in a read buffer until replaced by the next byte from the slave.
15.5.2 Slave Mode
The SPI operates in slave mode when MSTR is clear. In slave mode, the SCK pin is the input for the serial
clock from the master.
A transmission begins when initiated by a master SPI. The byte from the master SPI begins shifting in on
the slave MOSI pin under the control of the master serial clock.
As the byte shifts in on the MOSI pin, a byte shifts out on the MISO pin to the master shift register. On the
eighth serial clock cycle, the transmission ends and sets the SPI flag, SPIF. At the same time that SPIF
182
Figure
Configure SPI modules as master or slave before enabling them. Enable
the master SPI before enabling the slave SPI. Disable the slave SPI before
disabling the master SPI.
Before a transmission occurs, the SS pin of the slave SPI must be at logic 0.
The slave SS pin must remain low until the transmission is complete.
15-3.
SHIFT REGISTER
MASTER MCU
DIVIDER
CLOCK
Figure 15-3. Full-Duplex Master/Slave Connections
MC68HC812A4 Data Sheet, Rev. 7
MISO
MOSI
SCK
SS
NOTE
NOTE
V
DD
MISO
MOSI
SCK
SS
SHIFT REGISTER
SLAVE MCU
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