Overview Of The 16-Bit Reload Timer - Fujitsu MB90460 Series Hardware Manual

CHAPTER 12 16-BIT RELOAD TIMER
12.1

Overview of the 16-bit Reload Timer

The 16-bit reload timer functions in the two modes shown below, either of which can be
selected. It is synchronized with three types of internal clocks for counting down in
internal clock mode, and it counts down by detecting an optional edge input to the
external pin in event counter mode.
This timer defines that an underflow condition results when the counter value changes
from 0000 to FFFF
H
setting value + 1] counts.
Either of two modes can be selected for counting. In load mode, the value set for the
count is reloaded to repeat counting for an underflow. In single-shot mode, the
counting is stopped with an underflow.
The counter underflow allows the occurrence of an interrupt and coordination with the
extended intelligent I/O service (EI
The MB90460/465 series 16-bit reload timer has two built-in channels.
■ Overview of the 16-bit Reload Timer
●
16-bit reload timer operating modes
Table 12.1-1 lists the operating modes of the 16-bit reload timer.
Table 12.1-1 16-bit Reload Timer Operating Modes
Clock mode
Internal clock mode
Event count mode
(external clock mode)
■ Internal Clock Mode
Internal clock mode allows selection of one of three types of internal clock for the following operations:
●
Software trigger operation
When "1" is written to the TRG bit of the timer control status register (TMCSRL0/TMCSRL1), counting
starts. Trigger input by the TRG bit is always valid for external trigger input as well as for external gate
input.
●
External trigger operation
When selected edges (rising, falling, and both edges) are input to the TIN0 and TIN1 pins, counting starts
in channel 0 and 1 respectively.
●
External gate input operation
While the selected signal level (L or H) is being input to TIN0 and TIN1 pins, counting continues in
channel 0 and 1 respectively.
230
. Thus, an underflow will occur after an interval of [reload register
H
2
OS).
Counter operation
Reload mode
One-shot mode
Reload mode
One-shot mode
Operation of 16-bit reload timer
Software trigger operation
External trigger operation
External gate input operation
Software trigger operation