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5-11. Key Scan and Display Circuit
5. Circuit Descriptions
The step signals of DC 11 ∼ 12V will be generated periodically. If a sink signal
outputs from IC4, DC 11-12V will be applied to the LED input terminal and sink
the LED output terminal to 0V. Therefore, LED will be ON for 2 miliseconds.
2) Key Scan
The 6 step signals, Q6∼Q4 are applied to scan the 6 keys (buttons). When SW6
is pressed, the step signal from Q6
will be reduced to 5V and entered to the MICOM, then MICOM will match a
corresponding function for SW6 key.
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