Fujitsu FR81S User Manual
CHAPTER 19: BASE TIMER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: BASE TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
49
5.4.1. Overview
This section explains the overview of the 16/32-bit reload timer operation.
The 16/32-bit reload timer is a timer that decreases from the value set in the base timer x cycle setting register
(BTxPCSR). This timer has a function of generating an underflow interrupt request when the down counter
underflows.
The 16/32-bit reload timer has two modes: Timer mode and operation mode. The operation of the timer varies
in accordance with combinations of these modes.
⋅
Timer mode: One of the following two modes can be selected using the T32 bit of the base timer x timer
control register (BTxTMCR).
⋅
16-bit timer mode (T32 = 0): 16-bit reload timer can operate individually for each of the channels.
⋅
32-bit timer mode (T32 = 1): 2 channels can be cascaded and used as a 32-bit reload timer.
⋅
Operation mode: One of the following two modes can be selected using the MDSE bit of the base timer
x timer control register (BTxTMCR).
⋅
Reload mode (MDSE = 0): In this mode, when the down counter underflows, the preset value (cycle)
is reloaded to allow the timer to restart counting.
⋅
One-shot mode (MDSE = 1): Once the down counter underflows, the counter will no longer count.
MB91520 Series
MN705-00010-1v0-E
682