
R8C/14 Group, R8C/15 Group 15. Clock Synchronous Serial I/O with Chip Select (SSU)
Rev.2.10 Jan 19, 2006 Page 167 of 253
REJ09B0164-0210
15.6.4 SCS Pin Control and Arbitration
When setting the SSUMS bit in the SSMR2 register to “1” (4-wire bus communication mode).and the
CSS1 bit in the SSMR2 register to “1” (functions as SCS
output pin), Set the MSS bit in the SSCRH
register to “1” (operates as a master device) and check the arbitration of the SCS
pin before starting
serial transfer. If the SSU detects that the synchronized internal SCS
signal is held “L” in this period,
the CE bit in the SSSR register to “1” (a conflict error occurs) and the MSS bit is automatically set to
“0” (operates as a slave device).
Figure 15.20 shows an Arbitration Check Timing.
A future transmit operation is not performed while the CE bit is set to “1”. Set the CE bit to “0” (a
conflict error does not occur) before a transmit is started.
Figure 15.20 Arbitration Check Timing
Data Write to
SSTDR Register
Maximum Time of SCS Internal
Synchronization
During Arbitration Detection
High-Impedance
SCS Input
Internal SCS
(Synchronization)
MSS Bit in
SSCRH Register
Transfer Start
CE
SCS Output
“0”
“1”
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