Internal Clock And External Clock Operations Of 16-Bit Reload Timer - Fujitsu MB90390 Series Hardware Manual

14.3 Internal Clock and External Clock Operations of 16-bit
Reload Timer
The machine clock divided by 2
operating the timer from an internal divide clock. The external input pin can be selected
as either a trigger input or gate input by a register setting.
If an external clock is selected, the TIN pin functions as an external event input pin to
count the number of valid edges set in the register.
■ Internal Clock Operation of 16-bit Reload Timer
Writing "1" to both the CNTE and TRG bits in the control register enables and starts counting at one time.
Using the TRG bit as a trigger input is always available when the timer is enabled (CNTE = 1), regardless
of the operation mode.
Figure 14.3-1 shows the activation and operation of 16-bit reload timer counter. A time period T (T:
machine cycle) is required from the counter start trigger being input until the reload register data is loaded
into counter.
Figure 14.3-1 Activation and Operation of 16-bit Reload Timer Counter
Count clock
Counter
Data load
CNTE (bit)
TRG (bit)
CHAPTER 14 16-BIT RELOAD TIMER (WITH EVENT COUNT FUNCTION)
1 3 5
, 2 , or 2 can be selected as the clock sources for
Reload data
T
-1 -1 -1
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