MC68HC908GR8CFA Freescale Semiconductor, MC68HC908GR8CFA Datasheet - Page 307

• Manufacturer Part Number: MC68HC908GR8CFA
• Description: IC MCU FLSH 8BIT8MHZ 7.5K32-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908GR8CFA

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 21
• Program Memory Size: 7.5KB (7.5K x 8)
• Program Memory Type: FLASH
• Ram Size: 384 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

20.6.4 Transmission Initiation Latency
MC68HC908GR8 — Rev 4.0
MOTOROLA
When CPHA = 1 for a slave, the first edge of the SPSCK indicates the
beginning of the transmission. This causes the SPI to leave its idle state
and begin driving the MISO pin with the MSB of its data. Once the
transmission begins, no new data is allowed into the shift register from
the transmit data register. Therefore, the SPI data register of the slave
must be loaded with transmit data before the first edge of SPSCK. Any
data written after the first edge is stored in the transmit data register and
transferred to the shift register after the current transmission.
When the SPI is configured as a master (SPMSTR = 1), writing to the
SPDR starts a transmission. CPHA has no effect on the delay to the start
of the transmission, but it does affect the initial state of the SPSCK
signal. When CPHA = 0, the SPSCK signal remains inactive for the first
half of the first SPSCK cycle. When CPHA = 1, the first SPSCK cycle
begins with an edge on the SPSCK line from its inactive to its active
level. The SPI clock rate (selected by SPR1:SPR0) affects the delay
from the write to SPDR and the start of the SPI transmission. See
20-7. The internal SPI clock in the master is a free-running derivative of
the internal MCU clock. To conserve power, it is enabled only when both
the SPE and SPMSTR bits are set. SPSCK edges occur halfway through
the low time of the internal MCU clock. Since the SPI clock is free-
running, it is uncertain where the write to the SPDR occurs relative to the
slower SPSCK. This uncertainty causes the variation in the initiation
delay shown in
time. That is, the maximum delay is two MCU bus cycles for DIV2, eight
MCU bus cycles for DIV8, 32 MCU bus cycles for DIV32, and 128 MCU
bus cycles for DIV128.
Freescale Semiconductor, Inc.
For More Information On This Product,
Serial Peripheral Interface (SPI)
Go to: www.freescale.com
Figure
20-7. This delay is no longer than a single SPI bit
Serial Peripheral Interface (SPI)
Transmission Formats
Technical Data
Figure
307