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SSR—Serial Status Register
7
Bit
TDRE
Initial value
1
Read/Write
R/(W)*
Transmit data register empty
0
[Clearing conditions] • Read TDRE when TDRE = 1, then write 0 in TDRE.
[Setting conditions]
1
Note: * Only 0 can be written, to clear the flag.
6
5
4
RDRF
ORER
FER/ERS
0
0
0
R/(W)*
R/(W)*
R/(W)*
Parity error
Framing error (for serial communication interface)
[Clearing conditions] • Reset or transition to standby mode
0
1
[Setting condition]
Error signal status (for smart card interface)
[Clearing conditions] • Reset or transition to standby mode
0
1
[Setting condition]
Overrun error
[Clearing conditions] • Reset or transition to standby mode
0
1
[Setting condition]
Receive data register full
[Clearing conditions] • Reset or transition to standby mode
0
• Read RDRF when RDRF = 1, then write 0 in RDRF.
[Setting condition]
Serial data is received normally and transferred from RSR to RDR.
1
• Reset or transition to standby mode
• TE is 0 in SCR.
• Data is transferred from TDR to TSR, enabling new data to be written in TDR
3
2
1
PER
TEND
MPB
0
1
0
R/(W)*
R
R
Multiprocessor bit
0
1
Transmit end (for serial communication interface)
[Clearing conditions]
0
Read TDRE when TDRE = 1, then write 0 in TDRE.
[Setting conditions]
• Reset or transition to standby mode
• TE is cleared to 0 in SCR.
1
• TDRE is 1 when last bit of 1-byte serial character is
transmitted.
Transmit end (for smart card interface)
[Clearing conditions]
0
Read TDRE when TDRE = 1, then write 0 in TDRE.
[Setting conditions]
• Reset or transition to standby mode
• TE is cleared to 0 in SCR and FER/ERS is cleared to 0.
1
• TDRE is 1 and FER/ERS is 0 (normal transmission)
2.5 etu* (when GM = 0) or 1.0 etu (when GM = 1) after
1-byte serial character is transmitted.
Note: * etu: Elementary time unit (time required to transmit one bit)
[Clearing conditions] • Reset or transition to standby mode
0
• Read PER when PER = 1, then write 0 in PER.
[Setting condition]
Parity error (parity of receive data does not match parity
1
setting of O/E bit in SMR)
• Read FER when FER = 1, then write 0 in FER.
Framing error (stop bit is 0)
• Read ERS when ERS = 1, then write 0 in ERS.
A low error signal is received.
• Read ORER when ORER = 1, then write 0 in ORER.
Overrun error (reception of the next serial data ends when RDRF = 1)
H'FFFB4
0
MPBT
0
R/W
Multiprocessor bit transfer
0
Multiprocessor bit value in transmit data is 0
1
Multiprocessor bit value in transmit data is 1
Multiprocessor bit value in receive data is 0
Multiprocessor bit value in receive data is 1
SCI0
575
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