Fujitsu FR81S User Manual
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
6. Operation of CSIO
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
182
6.1.2.
Reception Interrupts and Flag Setting Timing
Reception interrupts occur either when the reception is completed (SSR:RDRF) or when a reception error
occurs (SSR:ORE).
When the last data bit is detected, reception data is stored in the receive data register (RDR). When
reception is completed (SSR:RDRF=1) or a reception error occurs (SSR:ORE=1), a corresponding flag is
set. If reception interrupts are enabled (SCR:RIE=1) at this time, a reception interrupt occurs.
Note:
⋅
When a reception error occurs, the data in the receive data register (RDR) becomes invalid.
Figure 6-1 Timing of Flag Setting
Reception operation and flag setting timing
SCK
SIN
Reception data
sampling
sampling
D0
D1
D2
D3
D4
D5
D6
D7
RDRF
Generateion of reception interrupt
<Notes>
The figure shows the timing under the following condition:
SCR:MS=1, SPI=0
ESCR:L3~L0=0000b
SMR:SCINV=0, BDS=0, SCKE=0, SOE=0
The figure shows the timing under the following condition:
SCR:MS=1, SPI=0
ESCR:L3~L0=0000b
SMR:SCINV=0, BDS=0, SCKE=0, SOE=0
Timing to set ORE(overrun error) flag bit
SCK
SIN
Reception data
sampling
sampling
D0 D1 D2 D3 D4 D5 D6 D7 D0 D1 D2 D3 D4 D5 D6 D7
RDRF
Overrun error occurrence*
ORE
<Notes>
The figure shows the timing under the following condition:
SCR:MS=1, SPI=0
ESCR:L3~L0=0000b
SMR:SCINV=0, BDS=0, SCKE=0, SOE=0
The figure shows the timing under the following condition:
SCR:MS=1, SPI=0
ESCR:L3~L0=0000b
SMR:SCINV=0, BDS=0, SCKE=0, SOE=0
*:An overrun error occurs when the next data is transferred before the reception data is read(RDRF=1)
MB91520 Series
MN705-00010-1v0-E
1495