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VII - 11
Chapter 7 16-bit Timer
16-bit Timer Count
Count Timing of Timer Operation (Timer 7)
The binary counter counts up with the selected clock source as the count clock.
The basic operation of the whole function of 16-bit timer is as follows ;
(A) When any data is written to the preset register as the TM7EN flag is stopped ("0"), the same
value is loaded at the writing cycle and the binary counter is cleared to x'0000'.
(B) If the TM7EN flag is "1", the binary counter starts counting. The counting is happened at the
falling edge of the count clock.
Figure 7-3-1 Count Timing of Timer Operation (Timer 7)
Table 7-3-2 Clock Source at Timer Operation(Timer 7)
Table 7-3-2 shows the clock source that can be selected.
0002 0003
NM
0000 0001 0002 N-1
N
0000 0001
Count
clock
TM7EN
flag
Compare
register
Binary
counter
Interrupt
request flag
(A) (B)
(C)
(D)
(E)
NM
Preset
register
(A)
(A)
fosc 50 ns
fosc/2 100 ns
fosc/4 200 ns
fosc/16 800 ns
fs 100 ns
fs/2 200 ns
fs/4 400 ns
fs/16 1.6
µ
s
Clock source 1 count time
Notes : as fosc = 20 MHz fx = 32.768 kHz fs
= fosc/2 = 10 MHz