VII - 63
Chapter 7
16-bit Timers
16-bit Timer Capture
When setup is as following (1), (2), and external interrupt valid edge is switched by program, interrupt
request and capture trigger are generated.
(1)
at switching the valid edge from the falling to the rising, when the interrupt pin is "H" level.
(2)
at switching the valid edge from the rising to the falling, when the interrupt pin is "L" level.
This does not happen, if the interrupt edge is switched after the generation of an valid edge interrupt set
in advance. But when the both edges interrupt function is used, this could happen. The noise influence
should be considered when operating the interrupt flag on program.
N
0113 0114
5555 5556
Count
clock
TM7EN
flag
Compare
register
Binary
counter
External
interrupt m
Capture
register
5557 5558
N-1
N
0000 0001
0111 0112
N
0114
0000
0111
Capture
trigger
5558
5555
nCapture Count Timing as a Both Edges of External Interrupt Signal is selected as a Trigger (Timer 7)
A capture trigger is generated at the both edges of the external interrupt m input signal. In synchronized
with this capture trigger, the value of binary counter is loaded to the input capture register. The value
loaded to the capture register is depending on the value of a binary counter at the falling edge of a
capture trigger. When the specified edge is selected as a capture trigger source, a capture trigger is
generated only at that edge. The other count timing is same as the count timing of the timer operation.
Figure 7-9-1
Capture Count Timing as an External Interrupt Signal is selected as a Trigger
(Timer 7, Timer 8)
[
Chapter 3 3-3-4. Specified Polarity Edge Interrupt ]
When the binary counter is used as a free counter which counts x'0000' to x'FFFF', set the
compare register 1 to x'FFFF', or set the TMnBCR flag of the TM7MD2 or TM8MD3 register
to "0".
Even if an event is generated before the value of the input capture register is read out, the
value of the input capture register can be rewritten.
In the initial state after releasing the reset, the generation of trigger by the external interrupt
signal is disabled. Set the TnICEN flag of the TMnMD2 register to "1" to enable the trigger
generation.