Renesas M32R/ECU Series, User Manual

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Appendix 4
Appendix
4-28
32180 Group User's Manual (Rev. 1.0)
SUMMARY OF PRECAUTIONS
(2) Avoiding effects of rapidly level-changing signal lines
Locate signal lines whose levels change rapidly as far away from the oscillator as possible. Also, make sure
the rapidly level-changing signal lines will not intersect the clock-related signal lines and other noise-sensi-
tive signal lines.
<Reasons>
Rapidly level-changing signal lines tend to affect other signal lines as their voltage level frequently rises and
falls. Especially if these signal lines intersect the clock-related signal lines, they will cause the clock waveform
to become distorted, which may result in the microcomputer operating erratically or getting out of control.
Figure 4.13.8 Example Wiring of a Rapidly Level-Changing Signal Line
XIN
XOUT
VCNT
High-speed serial I/O
High-speed timer input/output, etc.
Signal line intersecting the clock-related and other signal lines
XIN
XOUT
VCNT
High-speed serial I/O
High-speed timer input/output, etc.
Locate the signal line away from the clock-related and other signal lines
Appendix 4.13 Precautions about Noise