Overview Of 16-Bit Reload Timer - Fujitsu MB90420/5 (A) Series Hardware Manual

This chapter explains the functions and the operations of 16-bit reload timer.

10.1 Overview of 16-bit Reload Timer

The 16-bit reload timer has two types of clock modes:
synchronously with three types of internal clocks, and the event count mode which decrements after
detecting any edge of the pulse input to the external pin. Either of these modes can be selected. This timer
defines underflow as the counter value changing from 0000
when [setting value of reload register + 1] is counted. Also, the timer has two different counting modes: the
reload mode in which an underflow reloads the count setting for repetitive counting, and the one-shot mode
in which an underflow reloads stops the count. Either of these modes can be selected. The timer can cause
a counter underflow to generate an interrupt, and also conforms to expansion intelligent I/O service (EI
n 16-bit reload timer operation mode
The operation mode of the 16-bit reload timer is as shown in Table 10-1.
Clock Mode
Internal clock mode
Event count mode
(external clock mode)
n Internal clock mode
The count clock can be selected from three types of internal clocks, and one of the following operations can
be selected:
• Software trigger operation
The count is started when 1 is written to the TRG bit of the timer control status register (TMCSR0/1). The
trigger input by TRG bit is enabled at external trigger input and external gatre input.
• External trigger operation
The count is started when the selected edge (rising, falling, or both edges) is input to the TIN0/1 pin.
• External gate input operatoin
The count continues while the selected signal level (L or H) is input to the TIN0/1 pin.
n Event count mode (external clock mode)
When the selected edge (rising, falling, or both edges) is input to the TIN0/1 pin, decrementing is performed
on that edge. When an external clock with a certain cycle is used, the timer can also be used as an interval
timer.
16-BIT RELOAD TIMER
Table 10-1 Operating Mode of 16-bit Reload Timer
Counter Operation
Reload mode
One-shot mode
Reload mode
One-shot mode
the internal clock mode which decrements
to FFFF . Consequently, an underflow occurs
H H
Operation of 16-bit Reload Timer
Software trigger operation
External trigger operation
External gate input operation
Software trigger operation
10-3
2
OS).