7751 Group User’s Manual
20–62
APPENDIX
Appendix 8. Examples of noise immunity improvement
(2)
Wiring for clock input/output pins
Make the length of wiring connected to the clock input/output pins as short as possible.
Make the length of wiring between the grounding lead of the capacitor, which is connected to
the oscillator and Vss pin of the microcomputer, as short as possible (within 20 mm).
Separate the Vss pattern for oscillation from all other Vss patterns. (Refer to Figure 14.)
Reason:
The microcomputer’s operation
synchronizes with a clock generated
by the oscillation circuit.
If noise enters clock I/O pins, clock
waveforms may be deformed. This
may cause a malfunction or a
program runaway.
Also, if the noise causes a potential
difference between the Vss level
of the microcomputer and the Vss
level of an oscillator, the correct
clock will not be input in the
microcomputer.
(3)
Wiring for CNVss pin
Connect CNVss pin to Vss pin with the shortest possible wiring.
Reason:
T h e p r o c e s s o r m o d e o f t h e
microcomputer is influenced by a
potential at CNVss pin when
C N V s s a n d V s s p i n s a r e
connected.
If the noise causes a potential
difference between CNVss and
Vss pins, the processor mode may
become unstable. This may cause
a microcomputer malfunction or
a program runaway.
Fig. 6. Wiring for clock input/output pins
Fig. 7. Wiring for CNVss pin
Noise
X
IN
X
OUT
Vss
X
IN
X
OUT
Vss
M37751
M37751
Not
acceptable
Acceptable
Noise
CNVss
Vss
M37751
CNVss
Vss
M37751
Acceptable
Not
Acceptable
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Summary of Contents for 7700 FAMILY
Page 2: ...MITSUBISHI 16 BIT SINGLE CHIP MICROCOMPUTER 7700 FAMILY 7751 SERIES 7751 Group User s Manual...
Page 11: ...Table of Contents viii 7751 Group User s Manual MEMORANDUM...
Page 157: ...TIMER B 6 28 7751 Group User s Manual 6 5 Pulse period pulse width measurement mode MEMORANDUM...
Page 245: ...7751 Group User s Manual 8 36 A D CONVERTER Precautions when using A D converter MEMORANDUM...
Page 265: ...7751 Group User s Manual WAIT MODE 11 6 11 3 Precautions for Wait mode MEMORANDUM...
Page 289: ...CONNECTION WITH EXTERNAL DEVICES 12 4 Hold function 7751 Group User s Manual 12 24 MEMORANDUM...
Page 290: ...CHAPTER 13 RESET 13 1 Hardware reset 13 2 Software reset...
Page 302: ...CHAPTER 14 CLOCK GENERATING CIRCUIT 14 1 Oscillation circuit example 14 2 Clock...
Page 307: ...CLOCK GENERATING CIRCUIT 7751 Group User s Manual 14 6 14 2 Clock MEMORANDUM...
Page 360: ...CHAPTER 16 STANDARD CHARACTERISTICS 16 1 Standard characteristics...
Page 366: ...CHAPTER 17 APPLICATIONS 17 1 Memory expansion...
Page 405: ...APPLICATIONS 7751 Group User s Manual 17 40 17 1 Memory expansion MEMORANDUM...
Page 406: ...CHAPTER 18 PROM VERSION 18 1 EPROM mode 18 2 Usage precaution...
Page 417: ...7751 Group User s Manual PROM VERSION 18 12 18 2 Usage precaution MEMORANDUM...
Page 418: ...CHAPTER 19 FLASH MEMORY VERSION 19 1 Parallel input output mode 19 2 Serial input output mode...
Page 451: ...FLASH MEMORY VERSION 7751 Group User s Manual 19 34 19 2 Serial input output mode MEMORANDUM...
Page 484: ...APPENDIX 7751 Group User s Manual 20 33 Appendix 4 Package outlines 80D0...
Page 489: ...APPENDIX 7751 Group User s Manual 20 38 Appendix 6 Hexadecimal instruction code table...
Page 490: ...APPENDIX 7751 Group User s Manual 20 39 Appendix 6 Hexadecimal instruction code table...
Page 492: ...APPENDIX 7751 Group User s Manual 20 41 Appendix 7 Machine instructions...
Page 493: ...APPENDIX 7751 Group User s Manual 20 42 Appendix 7 Machine instructions...
Page 494: ...APPENDIX 7751 Group User s Manual 20 43 Appendix 7 Machine instructions...
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Page 511: ...APPENDIX 7751 Group User s Manual 20 60 Appendix 7 Machine instructions...
Page 535: ...APPENDIX Appendix 9 Q A 7751 Group User s Manual 20 84 MEMORANDUM...
Page 536: ...GLOSSARY...
Page 539: ...GLOSSARY 7751 Group User s Manual 4 MEMORANDUM...