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R8C/33C Group
24.5.1
24. Synchronous Serial Communication Unit (SSU)
Initialization in 4-Wire Bus Communication Mode
Figure 24.10 shows Initialization in 4-Wire Bus Communication Mode. Before the data transit/receive
operation, set the TE bit in the SSER register to 0 (transmit disabled), the RE bit in the SSER register to 0
(receive disabled), and initialize the synchronous serial communication unit.
To change the communication mode or format, set the TE bit to 0 and the RE bit to 0 before making the change.
Setting the RE bit to 0 does not change the settings of flags RDRF and ORER or the contents of the SSRDR
register.
Start
RE bit ← 0
TE bit ← 0
SSER register
SSUMS bit ← 1
SSMR2 register
(1)
SSMR register
Set bits CPHS and CPOS
MLS bits ← 0
SSCRH register
SSMR2 register
(2)
SSCRH register
SSSR register
SSER register
(1) The MLS bit is set to 0 for MSB-first transfer.
The clock polarity and phase are set by bits
CPHS and CPOS.
Set MSS bit
SCKS bit ← 1
Set bits SOOS, CSS0 to
CSS1, and BIDE
(2) Set the BIDE bit to 1 in bidirectional mode and
set the I/O of the SCS pin by bits CSS0 and
CSS1.
Set bits CKS0 to CKS2
Set RSSTP bit
ORER bit ← 0 (1)
RE bit ← 1 (receive)
TE bit ← 1 (transmit)
Set bits RIE, TEIE, and TIE
End
Note:
1. Write 0 after reading 1 to set the ORER bit to 0.
Figure 24.10
Initialization in 4-Wire Bus Communication Mode
REJ09B0570-0100 Rev.1.00 Dec. 14, 2009
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