
R8C/3JM Group
25. Synchronous Serial Communication Unit (SSU)
R01UH0285EJ0100 Rev.1.00
Aug 08, 2011
25.2.10 SS Status Register (SSSR)
Notes:
1. Writing 1 to CE, ORER, RDRF, TEND, or TDRE bits is invalid. To set any of these bits to 0, first read 1 then write
0.
2. When the serial communication is started while the SSUMS bit in the SSMR2 register is set to 1 (four-wire bus
communication mode) and the MSS bit in the SSCRH register is set to 1 (operates as master device), the CE bit
is set to 1 if “L” is applied to the SCS pin input. Refer to 25.5.4 SCS Pin Control and Arbitration for more
information.
When the SSUMS bit in the SSMR2 register is set to 1 (four-wire bus communication mode), the MSS bit in the
SSCRH register is set to 0 (operates as slave device) and the SCS pin input changes the level from “L” to “H”
during transfer, the CE bit is set to 1.
3. Indicates when overrun errors occur and receive completes by error reception. If the next serial data receive
operation is completed while the RDRF bit is set to 1 (data in the SSRDR register), the ORER bit is set to 1.
After the ORER bit is set to 1 (overrun error), receive operation is disabled while the bit remains 1.
4. The RDRF bit is set to 0 when reading out the data from the SSRDR register.
5. Bits TEND and TDRE are set to 0 when writing data to the SSTDR register.
When reading these bits immediately after writing to the SSTDR register, insert three or more NOP instructions
between the instructions used for writing and reading.
6. The TDRE bit is set to 1 when the TE bit in the SSER register is set to 1 (transmit enabled).
If the SSSR register is accessed continuously, insert one or more NOP instructions between the instructions
used for access.
Address 019Ch
Bit
b7b6b5
b4b3b2
b1b0
Symbol
After Reset
000
00
Bit
Symbol
Bit Name
Function
R/W
b0
CE
0: No conflict errors generated
1: Conflict errors generated
(2)R/W
b1
—
Nothing is assigned. If necessary, set to 0. When read, the content is 0.
—
b2
ORER
0: No overrun errors generated
1: Overrun errors generated
(3)R/W
b3
—
Nothing is assigned. If necessary, set to 0. When read, the content is 0.
—
b4
—
b5
RDRF
Receive data register full flag
(1, 4) 0: No data in SSRDR register
1: Data in SSRDR register
R/W
b6
TEND
0: The TDRE bit is set to 0 when transmitting the last
bit of transmit data
1: The TDRE bit is set to 1 when transmitting the last
bit of transmit data
R/W
b7
TDRE
0: Data is not transferred from registers SSTDR to
SSTRSR
1: Data is transferred from registers SSTDR to
SSTRSR
R/W