| 摘要 |
PURPOSE: An apparatus for recognizing key signals in a multifunctional telephone is provided to install an isolation circuit between a main microprocessor and an auxiliary microprocessor so as to recognize key signals regardless of the supply of external power. CONSTITUTION: An apparatus for recognizing key signals in a multifunctional telephone comprises a main microprocessor(100), an auxiliary microprocessor(110), a keypad(120), and an isolation circuit(130). The main microprocessor(100) works when power is supplied from the external. The main microprocessor(100) outputs timing signals to its own row output ports(P11-P14) at regular intervals of time. The auxiliary microprocessor(110) works when power is not supplied from the external. The keypad(120), arranged in a 4x3 matrix, has 10 numeric keys and 2 function keys. The isolation circuit(130) is to separate the main microprocessor(100) from the auxiliary microprocessor(110).
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