Synchronous Serial Port
LH79524/LH79525 User’s Guide
14-4
Version 1.0
14.1.2 Motorola SPI Frame Format
For the Motorola SPI format, the serial frame pin (SSPFRM) is active LOW. The SPO and
SPH bits in SSP Control Register 0 influence SSPCLK and SSPFRM operation in Single
and Continuous Modes.
Figure 14-2 and Figure 14-3 show the Motorola SPI frame format for single data transfers,
continuous data transfers, and when SPH equals 0 or 1.
Figure 14-2. Motorola SPI Frame Format (Continuous Transfer)
Figure 14-3. Motorola SPI Frame Format with SPH = 0
LH79525-74
SSPCLK
SSPFRM
SSPTXD/
SSSRXD
4 to 16 BITS
LSB
NOTE: SPH = '0', SPO = '0'.
LSB
MSB
MSB
SSPFRM
SSPRX
(from slave)
SSPTX
(from master)
SSPCLK
(SPO = 1)
SSPCLK
(SPO = 0)
NOTE: Q = Undefined.
MSB
MSB
LSB
LSB
Q
LH79525-75