m37905 Renesas Electronics Corporation., m37905 Datasheet - Page 540

• Manufacturer Part Number: m37905
• Description: Mitsubishi 16-bit Single-chip Microcomputer 7700 Family / 7900 Series
• Manufacturer: Renesas Electronics Corporation.

5. Setup for I/O ports
Setup I/O ports by hardware and software as follows:
<Hardware protection>
<Software protection>
6. Reinforcement of the power source line
layers.
When using a multilayer printed circuit board, the Vss and Vcc patterns must each be one of the middle
Connect a resistor of 100
Read the data of an input port several times to confirm that input levels are equal.
periodically.
Rewrite data to port Pi direction registers periodically.
For the Vss and Vcc lines, use thicker wiring than that of other signal lines.
The following is necessary for double-sided printed circuit boards:
•On one side, the microcomputer is installed at the center, and the Vss line is looped or meshed around
•On the opposite side, the Vcc line is wired the same as the Vss line.
Since the output data may reverse because of noise, rewrite data to the output port’s Pi register
it. The vacant area is filled with the Vss line.
or more to an I/O port in series.
7905 Group User’s Manual Rev.1.0
Appendix 7. Countermeasure against noise
Fig. 11 Setup for I/O ports
Data bus
Direction register
Port latch
APPENDIX
Port
Noise
20-109