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CHAPTER 9 12-BIT PPG TIMER
9.5 Operations of 12-bit PPG Timer Functions
The 12-bit PPG timer can be used as a 12-bit PPG because the output pulse cycle period
and "H" pulse width can be set separately.
■ Example of Operations of 12-bit PPG Timer Functions
To operate the 12-bit PPG timer, the bits of the registers must be set as shown in Figure 9.5-1 .
Figure 9.5-1 Setting 12-bit PPG Timer
When 12-bit PPG outputs are enabled, the 12-bit counter starts counting from" 000
H"
in synchronization
with the selected count clock and the PPG pin is maintained at "H" level until a count by the counter is
synchronized with the compare value for the "H" width. The PPG pin is then maintained at "L" level until a
count by the counter is synchronized with the compare value for the cycle period. At this time, the 12-bit
counter is cleared and restarts counting from "000
H"
. Because the "H" width and cycle period can be set
separately, the timer can be used as a 12-bit PPG.
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
RCR21
RCK1
RCK0 HSC5 HSC4 HSC3 HSC2 HSC1 HSC0
RCR22 HSC11 HSC10 HSC9 HSC8 HSC7 HSC6
RCR23
RCEN
SCL5 SCL4 SCL3 SCL2 SCL1 SCL0
1
RCR24 SCL11
SCL10 SCL9 SCL8 SCL7 SCL6
1
: Used bit
: Set "1"