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10.6
Precautions when Using 8-/16-bit PPG Timer
Precautions when Using 8-/16-bit PPG Timer
I Precautions when Using 8-/16-bit PPG Timer
G
Effect on 8-/16-bit PPG timer when using timebase timer output
• If the output signal of the timebase timer is used as the input signal for the count clock of the 8-/16-bit
PPG timer (PPG01: PCM2 to PCM0 = "111
first count cycle in which the PPG timer is started
• When the timebase timer counter is cleared during the count operation of the PPG down counter,
deviation may occur in the count cycle.
G
Setting of PPG reload registers when using 8-bit PPG timer
• The Low-level and High-level pulse widths are determined at the timing of reloading the values in the
Low-level PPG reload registers (PRLL0, PRLL1) to the PPG down counter.
• If the 8-bit PPG timer is used in the 8-bit PPG output 2-channel independent operation mode or the 8 +
8-bit PPG output operation mode, use a word instruction to set both High-level and Low-level PPG
reload registers (PRLL0/PRLH0, PRLL1/PRLH1) at the same
Using a byte instruction may cause an unexpected pulse to be generated.
[Example of rewriting PPG reload registers using byte instruction]
If you update the value in the High-level PPG reload register (PRLH) after updating the value in the Low-
level PPG reload register (PRLL) using a byte instruction immediately before the signal level of the PPG
pin changes from High to Low, a Low-level pulse width is generated after updating and a High-level pulse
width is generated before updating only once.
Figure 10.6-1 shows the waveform as the values in the PPG reload registers are rewritten using the byte
instruction.
Figure 10.6-1 Waveform when Values in PPG Reload Registers Rewritten Using Byte Instruction
PRLL
PRLH
A+B
PPG pin
: To renew the value of PPG reload register (PRLL) (A → C)
<1>
: To renew the value of PPG reload register (PRLH) (B → D)
<2>
A
B
A+B
A
B
A
<1> <2>
", PCS2 to PCS0 = "111
B
C
D
B+C
C+D
C+D
B
C
B
C
D
CHAPTER 10 8/16-bit PPG timer
"), deviation may occur in the
B
Timing to
C+D
renew reload
value
C
D
319
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