Fujitsu FR81S User Manual
CHAPTER 19: BASE TIMER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: BASE TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
76
5.6.4. Operation in One-Shot Mode
This section explains the operation in one-shot mode.
This section explains the operation in one-shot mode.
Counting Operation
Activation
It is the same operation as in reload mode. See "Operation" in "5.6.3 Operation in Reload Mode".
Counting Operation
Counting operation initiated by the entry of an activation trigger is explained below, using an example where
the OSEL bit of the timer control register (BTxTMCR) is set for normal polarity (OSEL = 0).
1. The value set in the base timer x L width setting reload register (BTxPRLL) is transferred to the 16-bit
down counter and the value set in the base timer x H width setting reload register (BTxPRLH) is
transferred to the buffer. The 16-bit down counter begins to count down from the value of the L width
setting reload register (BTxPRLL). The output signal (TOUT) is at the "L" level.
2. The 16-bit down counter completes counting down from the value of L width setting reload register
(BTxPRLL).
3. The buffered value of H width setting reload register (BTxPRLH) is reloaded to the 16-bit down
counter, which continues counting down. The output signal (TOUT) is at the "H" level.
4. The 16-bit down counter completes counting down from the value of H width setting reload register
(BTxPRLH), thus causing an underflow.
5. The counting stops.
Operation that is performed if reactivation is permitted or not during counting depends on whether
reactivation is permitted based on the RTGEN bit of the timer control register (BTxTMCR).
⋅
If reactivation is not permitted (RTGEN = 0): Any activation trigger is ignored when it is entered during
counting.
⋅
If reactivation is permitted (RTGEN =1): The TGIR bit of the status control register (BTxSTC) changes
to "1". In addition, the value of L width setting reload register
(BTxPRLL) is reloaded to the 16-bit down counter, which
starts counting.
MB91520 Series
MN705-00010-1v0-E
709