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
227
Figure 6-20 Transmission Operation by External Trigger (TRG1="0", TRG0="1")
0
STMR
STMCR
External
trigger
trigger
0
10
STMCR
TINT
1
st
Byte
2
nd
Byte
TDRE
Transmission
data
data
Output transmission data when there is a
match between STMR and STMCR
match between STMR and STMCR
No data transmission because
there is no data (TDRE=0)
there is no data (TDRE=0)
3
rd
Byte
L
TDR RW
TBI
4
th
Byte
Output transmission data when there is a
match between STMR and STMCR
match between STMR and STMCR
TBYTE0
2
1
0
2
1
0
2
2
Transmissions
counter*A
counter*A
Load
Load
*A:Internal counter to be count transmission bytes
If the edge of the external trigger which is set with the trigger selection bit (SACSR:TRG1, 0) is detected
during the transmission operation by the external trigger in progress under the following conditions, the
transmission will not start.
⋅
When transmission is disabled (SCR:TXE="0")
⋅
In slave mode (SCR:MS="1")
⋅
When the chip select error (SACSR:CSE="1") occurred
⋅
When there is no valid data in the transmission data register (SSR:TDRE)
However, when the transmission data register contains no valid data (SSR:TDRE="1") and the edge of the
external trigger set with the trigger selection bit (SACSR:TRG1, 0) is detected, writing the transmission
data to transmission data register starts a transmission immediately.
If the transmission data register (TDR) has valid transmission data (SSR:TDRE="0") after the data
transmission is completed as many as the number of data set to TBYTE, the transmission data will not be
sent until the edge of the external trigger which is set with the trigger selection bit (SACSR:TRG1, 0) is
detected next time.
However, if the synchronous transmission is enabled (SACSR:TSYNE="1") and the edge of the external
trigger which is set with the trigger selection bit (SACSR:TRG1, 0) is detected, the transmission will not be
stopped and the next transmission will be started after sending as much data as TBYTE0.
⋅
Transmission operation in progress (SSR:TBI="0")
If the reception operation by the external trigger is performed, disable serial data output (SMR:SOE="0"),
enable transmission operation (SCR:TXE="1"), enable reception operation (SCR:RXE="1"), and write
dummy data to TDR as many as the number of receptions.
MB91520 Series
MN705-00010-1v0-E
1540