| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power consumption of a key scan system. SOLUTION: By detecting the change of a key sense 1 signal 204 from 'Hi' to 'Low' through a detecting circuit 101, the change of a key state from opening state to pressing state is detected. The factor of the last key scan is held in a register 102. A comparator circuit 103 compares the detected result of the detecting circuit 101 with the factor of the last key scan held in the factor register 102. When the detected result of this time is different from the factor of the last time as a result, the start of key scan operation is instructed to a control part 104. When the compared result shows the same, the start of the operation is not instructed. Thus, since key scan is performed only when the state of key is changed, the power consumption of the key scan system can be reduced.
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