Input Pin Functions (For Internal Clock Mode); External Event Counter; Figure 15.4.3A Trigger Input Operation; Figure 15.4.3B Gate Input Operation - Fujitsu F2MC-16LX MB90580 Series Hardware Manual

15.4 Operation

15.4.3 Input pin functions (for internal clock mode)

The TIN pin can be used as either a trigger input or a gate input when an internal clock is selected as the
clock source. When used as a trigger input, input of an active edge causes the timer to load the reload
register contents to the counter and then start count operation after clearing the internal prescaler. Input a
pulse width of at least 2T (T is the machine cycle) to TIN.
Figure 15.4.3a shows the operation of trigger input.
Count clock
TIN
Prescaler clear
Counter
Load
When used as a gate input, the counter only counts while the active level specified by the MOD0 bit of the
control register is input to the TIN pin. In this case, the count clock continues to operate unless stopped.
The software trigger can be used in gate mode, regardless of the gate level. Input a pulse width of at least
2T (T is the machine cycle) to the TIN pin. Figure 15.4.3b shows the operation of gate input.
Count clock
TIN
Counter

15.4.4 External event counter

The TIN pin functions as an external event input pin when an external clock is selected. The counter
counts on the active edge specified in the register. Input a pulse width of at least 4T (T is the machine
cycle) to the TIN pin.
216 Chapter 15: 16-Bit Reload Timer (with Event Count Function)
Rising edge detected
Reload data
-1
2T-
2.5T

Figure 15.4.3a Trigger Input Operation

When MOD0 = "1" (Count when "H" is input)
-1

Figure 15.4.3b Gate Input Operation

-1
-1 -1
-1 -1
MB90580 Series