MMC2107 Datasheet, PDF (391/618 Pages) –

Freescale Semiconductor, Inc.
Serial Peripheral Interface Module (SPI)
Functional Description
BEGIN TRANSMISSION
SCK (CPOL = 0)
END TRANSMISSION
SCK (CPOL = 1)
SAMPLE INPUT
MOSI/MISO
CHANGE OUTPUT
MOSI PIN
CHANGE OUTPUT
MISO PIN
SS PIN OUTPUT
MASTER ONLY
SLAVE SS PIN
t_L
t_T t_I t_L
MSB FIRST (LSBFE = 0): MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB MINIMUM 1/2 SCK
LSB FIRST (LSBFE = 1):
LSB
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
MSB
FOR t_T, t_L, t_l
Legend:
t_L = Minimum leading time before the first SCK edge
t_T = Minimum trailing time after the last SCK edge
t_I = Minimum idling time between transmissions (minimum SS high time)
t_L, t_T, and t_I are guaranteed for master mode and required for slave mode.
Figure 17-12. SPI Clock Format 0 (CPHA = 0)
NOTE:
When CPHA = 0, the slave SS pin must be negated and reasserted
between bytes.
Clock skew between the master and slave can cause data to be lost
when:
• CPHA = 0, and,
• The baud rate is the SPI clock divided by two, and
• The master SCK frequency is half the slave SPI clock frequency,
and
• Software writes to the slave SPIDR just before the synchronized
SS signal goes low.
MMC2107 – Rev. 2.0
MOTOROLA
Serial Peripheral Interface Module (SPI)
For More Information On This Product,
Go to: www.freescale.com
Technical Data
391