Read Panasonic KX-UT248RU / KX-UT248RU-B (serv.man3) Service Manual online
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KX-UT248RU/KX-UT248RU-B
4.2.6.
Key Circuit
The key data is under the matrix control by IC204.
The key information output from LED_STB is input into KEYIN, when the key is pressed.
The key information output from LED_STB is input into KEYIN, when the key is pressed.
The HOOK key is independent from Key Scan Matrix and taken into the port singularly.
KEY Input control timing chart
KEYIN pins have a internal pull-down resistor.
If KEY is pushed, high level is latched by connecting STB(output high) and KEYIN. If not, low level is latched.
The value is fixed by reading twice.
KEYIN pins have a internal pull-down resistor.
If KEY is pushed, high level is latched by connecting STB(output high) and KEYIN. If not, low level is latched.
The value is fixed by reading twice.
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