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CHAPTER 8 16-bit reload timer
8.1
Overview of 16-bit Reload Timer
The 16-bit reload timer has the following functions:
• The count clock can be selected from three internal clocks and external event clocks.
• A software trigger or external trigger can be selected as the start trigger.
• If the 16-bit timer register (TMR) underflows, an interrupt can be generated to the
CPU.The 16-bit reload timer can be used as an interval timer by using an interrupt.
• If the TMR underflows, either the one-shot mode for stopping the TMR count
operation, or the reload mode for reloading the value of the 16-bit reload register
(TMRLR) to the TMR to continue the TMR count operation can be selected.
• The hardware interrupt corresponds to the EI
• MB90895 series has two channels of 16-bit reload timers.
I Operation Modes of 16-bit Reload Timer
Table 8.1-1 indicates the operation modes of the 16-bit reload timer.
Table 8.1-1 Operation Modes of 16-bit Reload Timer
Internal clock mode
Event count mode
I Internal clock mode
• When the count clock select bits in the timer control status register (TMCSR: CSL1, CSL0) are set to
"00
", "01
B
• In the internal clock mode, the 16-bit reload timer decrements in synchronization with the internal clock.
• The count clock select bits in the timer control status register (TMCSR: CSL1, CSL0) can be used to
select three count clock cycles.
• The start trigger sets the edge detection for a software trigger or an external trigger.
246
Count Clock
Software trigger
External trigger
Software trigger
" or "10
", the 16-bit reload timer is set in the internal clock mode.
B
B
2
OS.
Start Trigger
Operation Performed upon
One-shot mode
Reload mode
One-shot mode
Reload mode
Underflow
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