
2.8 16-Bit Reload Timer (with Event Count Function)
162
Chapter 2: Hardware
(3) Input Pin Functions (in Internal Clock Mode)
When an internal clock is selected as a clock source, the TIN pin can be used as either a trigger input or
a gate input. When the TIN pin is used as a trigger input, the contents of the reload register are loaded
into the counter whenever a valid edge is input, and count operation starts after the input prescaler is
cleared.
The TIN input pulse should be at least 2 × T (T= machine cycles). Figure 2.8.5 illustrates trigger input
operation.
Fig. 2.8.5 Trigger Input Operation
When the TIN pin is used as a gate input, the count functions only as long as the signal input from the
TIN pin is at the valid level as determined by the MOD0 bit. During this time the count clock continues
to operate without stopping. In gate mode, software triggers are enabled regardless of gate level. The
pulse width at the TIN pin should be 2 × T (T = machine cycles) or more. Figure 2.8.6 illustrates gate
input operation.
Fig. 2.8.6 Gate Input Operation
(4) External Event Count
When the external clock source is selected, the TIN pin becomes an external event input pin, and counts
valid edges as defined by register setting. The pulse width at the TIN pin should be 4 × T (T = machine
cycles) or more.
Count clock
Prescaler clear
Counter
Load
Rising edge detected
Reload data
TIN
-1
2T to 2.5T
When MOD0 bit is ‘1’
Count clock
Counter
TIN
-1
(count functions during ‘H’ level input)
-1