Fujitsu FR81S User Manual
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
84
4.4.2.
Serial Status Register: SSR
The serial status register (SSR) allows you to check the status of transmission/reception and the reception
error flag and to detect the LIN break field as well as to clear the reception error flag.
SSRn(n=0 to 11) : Address Base addr + 02
H
(Access: Byte, Half-word, Word)
7
6
5
4
3
2
1
0
bit
REC Reserved LBD
FRE
ORE
RDRF
TDRE
TBI
0
-
0
0
0
0
1
1
Initial value
R0,W RX,WX R(RM1),
W
R,WX
R,WX
R,WX
R,WX
R,WX
Attribute
Bit name
Function
bit7 REC:
Reception error flag clear
bit
This bit clears the FRE and ORE flags of the serial status register (SSR).
⋅
To clear an error flag, write "1" to this bit.
⋅
Writing "0" does not affect anything.
A read always results in "0".
bit6 Reserved bit
Read: The value is indefinite.
Write: No effect on operation.
bit5 LBD:
LIN break field detection
flag bit
This bit indicates that LIN break field is detected.
When data with 11 or greater bits of "0" is input to serial input (SIN), LBD
bit is set to "1". In this case, when "1" is set to the LIN break field interrupt
enable bit (LBIE), a status interrupt will be generated.
(When read)
"1": LIN break field is detected.
"0": LIN break field Is not detected.
(When written)
"0" is written: LBD bit will be cleared.
"1" is written: No effect.
Note:
⋅
When a read-modify-write instruction is used, "1" will be read.
bit4 FRE:
Framing error flag bit
"0" Read: No framing error
"1" Read: There is a framing error
⋅
If a framing error occurs while a reception is in progress, this bit will be
set to "1". To clear this bit, write "1" to the REC bit of the serial status
register (SSR).
⋅
When the FRE bit and RIE bit are set to "1", a reception interrupt request
will be output.
⋅
If this flag is set, data contained in the receive data register (RDR)
becomes invalid.
⋅
When this flag is set while using the reception FIFO, the reception FIFO
enable bit will be cleared. As a result, the reception data will not be
stored in the reception FIFO.
MB91520 Series
MN705-00010-1v0-E
1397