SH7147 Datasheet, PDF (634/1108 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 14 Synchronous Serial Communication Unit
14.4 Operation
14.4.1 Transfer Clock
A transfer clock can be selected from seven internal clocks and an external clock. Before using
this module, enable the SSCK pin function in the PFC. When the MSS bit in SSCRH is 1, an
internal clock is selected and the SSCK pin is used as an output pin. When transfer is started, the
clock with the transfer rate set by bits CKS2 to CKS0 in SSMR is output from the SSCK pin.
When MSS = 0, an external clock is selected and the SSCK pin is used as an input pin.
14.4.2 Relationship of Clock Phase, Polarity, and Data
The relationship of clock phase, polarity, and transfer data depends on the combination of the
CPOS and CPHS bits in SSMR when the value of the SSUMS bit in SSCRL is 0. Figure 14.2
shows the relationship. When SSUMS = 1, the CPHS setting is invalid although the CPOS setting
is valid.
Setting the MLS bit in SSMR selects that MSB or LSB first communication. When MLS = 0, data
is transferred from the LSB to the MSB. When MLS = 1, data is transferred from the MSB to the
LSB.
(1) When CPHS = 0
SCS
SSCK
(CPOS = 0)
SSCK
(CPOS = 1)
SSI, SSO
(2) When CPHS = 1
SCS
SSCK
(CPOS = 0)
SSCK
(CPOS = 1)
SSI, SSO
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
Figure 14.2 Relationship of Clock Phase, Polarity, and Data
Rev. 3.00 Oct. 06, 2008 Page 610 of 1080
REJ09B0230-0300