![](http://datasheet.mmic.net.cn/330000/MB90457_datasheet_16437472/MB90457_36.png)
MB90455 Series
36
5.
16-bit Reload Timer
The 16-bit reload timer has the following functions:
Count clock is selectable among 3 internal clocks and external event clock.
Activation trigger is selectable between software trigger and external trigger.
Generation of CPU interrupt is allowed upon occurrence of underflow on 16-bit timer register. Available as an
interval timer using the interrupt function.
When underflow of 16-bit timer register (TMR) occurs, one of two reload modes is selectable between one-
shot mode that halts counting operation of TMR, and reload mode that reloads 16-bit reload register value to
TMR, continuing TMR counting operation.
The 16-bit reload timer is ready for expanded intelligent I/O service (EI
2
OS).
MB90455 series device has 2 channels of built-in 16-bit reload timer.
Operation mode of 16-bit reload timer
Count clock
Internal clock mode
The 16-bit reload timer is set to internal clock mode, by setting count clock selection bit (TMCSR: CSL1, CSL0)
to “00
B
”, “01
B
”, “10
B
”.
In the internal clock mode, the counter decrements in synchronization with the internal clock.
Three types of count clock cycles are selectable by count clock selection bit (TMCSR: CSL1, CSL0) in timer
control status register.
Edge detection of software trigger or external trigger is specified as an activation trigger.
Activation trigger
Operation upon underflow
Internal clock mode
Software trigger, external trigger
One-shot mode, reload mode
Event count mode
Software trigger
One-shot mode, reload mode