Operation Of 16-Bit Ppg Timer - Fujitsu MB90460 Series Hardware Manual

13.6

Operation of 16-bit PPG Timer

The 16-bit PPG Timer operate in either PWM mode or single shot mode. And
Retriggering can be enabled.
■ PWM Mode (PCNTL: MDSE = 0)
For PWM operation, the 16-bit down counter will be loaded with PCSR value, starts counting after a valid
trigger is detected. And once the 16-bit down counter reached zero, it is reloaded with PCSR value and
repeat counting again. PPG output is toggled when 16-bit down counter is reloaded. The period of the
output pulses can be controlled by setting PCSR and the duty ratio controlled by setting PDUT.
a) Retriggering is disabled (PCNTH: RTRG = 0)
Counter value
m
n
0
Software trigger
PPG
(normal polarity)
(inverted polarity)
b) Retriggering is enabled (PCNTH: RTRG = 1)
Counter value
m
n
0
Software trigger
PPG
(normal polarity)
PPG
(inverted polarity)
Figure 13.6-1 Retriggering is disabled in PWM Mode
Rising edge detected
(1)
(2)
(1) = (n+1)*T ns
(2) = (m+1)*T ns
Figure 13.6-2 Retriggering is enabled in PWM Mode
Rising edge detected
(2) = (m+1)*T ns
(1) = (n+1)*T ns
Trigger is ignored
T: Count clock period
m: PCSR value
n: PDUT value
Restarted by trigger
(1) m: PCSR value
n: PDUT value
(2)
T: Count clock period
CHAPTER 13 16-BIT PPG TIMER
Time
Time
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