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CHAPTER 9 12-BIT PPG TIMER
If the set "H" width is equal to or greater than the set cycle period, "H" level outputs occur.
■ 12-bit PPG Function
The timer’s programmable pulse output generator function can be used as a 12-bit PPG because it can set a
cycle period and "H" pulse width of output pulse waveforms separately. A range of controllable duty cycles
is 0.02% to 100%. However, the smaller the compare value for the cycle period, the lower the resolution
(the greater a minimum-step duty cycle).
If the compare value for the cycle period is "2", a comparative setting of "H" pulse width is 1 or 2 (a duty
cycle of 50% or 100%) and the resolution is 1/2.
An output frequency and a duty cycle can be calculated using the following equations:
Output pulse cycle period = Compare value for cycle period × Count clock cycle period
Duty cycle = Compare value for "H" width/Compare value × 100(%)
Table 9.1-2 lists available resolution values, minimum-step duty cycles, and output pulse cycle periods.
=10 × 2 × 0.32 µs
Cycle period = Compare value for cycle period × Count clock cycle period
= 011110
H
(30-clock period) × 2 × 4/F
CH
= 30 × 2 × 0.32 µs = 19.2 µs
"H" width = Compare value for "H" width × Count clock cycle period
= 001010
B
(10-clock width) × 2 × 4/F
CH
=6.4 µs
Table 9.1-2 Resolutions and Output Pulse Cycle Periods Supported when the Timer is Used as a 12-bit
PPG (1/2)
Compare
value for
cycle
period
Range of
available
compare
values for
"H" width
Output pulse cycle period
Resolution
Minimum-
step duty
cycle
Count clock
= 2 t
INST
Count clock
= 4 t
INST
Count clock
= 16 t
INST
Count clock
= 256 t
INST
0-
Unavailable
1-
21, 2
4 t
INST
8 t
INST
32 t
INST
512 t
INST
1/2 50.0%
31 to 3
6 t
INST
12 t
INST
48 t
INST
768 t
INST
1/3 33.3%
41 to 4
8 t
INST
16 t
INST
64 t
INST
1024 t
INST
1/4 25.0%
51 to 5
10 t
INST
20 t
INST
80 t
INST
1280 t
INST
1/5 20.0%
61 to 6
12 t
INST
24 t
INST
96 t
INST
1536 t
INST
1/6 16.7%
71 to 7
14 t
INST
28 t
INST
112 t
INST
1792 t
INST
1/7 14.3%
81 to 8
16 t
INST
32 t
INST
128 t
INST
2048 t
INST
1/8 12.5%