em78p809n ELAN Microelectronics Corp, em78p809n Datasheet - Page 45

• Manufacturer Part Number: em78p809n
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.0) 07.26.2005
(This specification is subject to change without further notice)
4.9.1 Timer Mode:
4.9.2 Counter Mode:
4.9.3 Window Mode
In Timer mode, counting up is performed using the internal clock. When the contents of
the up-counter matched with the TCR2 (TCR2H+TCR2L), then interrupt is generated
and the counter is cleared. Counting up resumes after the counter is cleared.
In Counter mode, counting up is performed using the external clock input pin (TC2 pin)
and either rising or falling can be selected by setting TC2ES. When the contents of
the up-counter matched with the TCR2 (TCR2H+TCR2L), then interrupt is generated
and the counter is cleared. Counting up resumes after the counter is cleared.
In Window mode, counting up is performed on the rising or falling edge of the pulse
that is logical AND of an internal clock and the TC2 pin (window pulse). When the
contents of the up-counter matched with the TCR2 (TCR2H+TCR2L), then interrupt is
generated and the counter is cleared. The frequency (window pulse) must be slower
than the selected internal clock.
Writing to the TCR2L, the comparison is inhibited until TCR2H is written.
Internal clock
Up-counter
Up-counter
TC2 interrupt
TC2 Pin
TC2 interrupt
TCR2
TCR2
Fig. 21. Counter Mode Timing Chart (TC2ES = 1)
n
0
Fig. 20. Timer Mode Timing Chart
n
0
1
1
2
2
3
3
4
4
5
n-2
n-3
n-2
match
match
8-Bit Microcontroller
n-1
n-1
n
n
0
EM78P809N
0
counter
counter
clear
1
clear
1
2
2
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3