
Under
development
1-79
Specifications in this manual are tentative and subject to change
Rev. H
Timer A
MITSUBISHI MICROCOMPUTERS
M30222 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(3) One-shot timer mode
In this mode, the timer operates only once as shown in Table 1.28. When a trigger occurs, the timer starts
up and continues operating for a given period. Figure 1.54 shows the Timer Ai mode register in one-shot
timer mode.
Usage Precautions
(1) Setting the count start flag to “0” while a count is in progress causes as follows:
The counter stops counting and a content of reload register is reloaded.
The TAiOUT pin outputs “L” level.
The interrupt request generated and the Timer Ai interrupt request bit goes to “1”.
(2) The Timer Ai interrupt request bit goes to “1” if the timer's operation mode is set using any of the following
procedures:
Selecting one-shot timer mode after reset.
Changing operation mode from timer mode to one-shot timer mode.
Changing operation mode from event counter mode to one-shot timer mode.
Therefore, to useTimer Ai interrupt (interrupt request bit), set Timer Ai interrupt request bit to “0” after the
above listed changes have been made.
Item
Specification
Count source
f1, f8, f32, fc32
Count operation
Timer counts down
When the count reaches 000016, the timer stops counting after reloading a new
count.
If a trigger occurs when counting, the timer reloads a new count and restarts
counting.
Divide ratio
1/n
n: Set value
Count start condition
An external trigger is input
Timer overflows
One-shot start flag is set (=1)
Count stop condition
A new count is reloaded after the count has reached 000016
The count start flag is reset (=0)
Interrupt request
generation timing
The count reaches 000016
TAiIN pin function
Programmable I/O port or trigger input
TAiOUT pin function
Programmable I/O port or pulse output
Read from timer
When Timer Ai register is read, it indicates an indeterminate value.
Write to timer
When counting stops
When a value is written to Timer Ai register, it is written to both reload register
and counter
When counting is in progress
When a value is written to Timer Ai register, it is written to only reload register
(Transferred to counter at next reload time).
Table 1.28. Timer specifications in one-shot timer mode