i want to use the calculator keypad as an input

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Thread Starter

Eng.aladdin eid

the problem is i can't find any datasheet for the calculator and with 29 bit line to the lcd its impossible to know how it works

can any one help me...????
 
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Curt Wuollet

Best way I've found is to get one of the Matrix Orbital displays with a keypad encoder and a keypad and communicate through its serial port. Most calculators would have two places you can access, the keypad crosspoint matrix and the LCD terminals. Niether provides a signal easily convertible to something usable. The keypad is the
best bet, but you need to monitor the scan and a coincidence signal. The LCD stuff is non standard voltages and really busy to deal with. It's quite a bit easier to use the Matrix Orbital as it has the keypad encoder and a serial port with the electronics to do the conversion. I succesfully used these for an input terminal and they were built into a time and attendance system at our plant as well. Bear in mind that this is advice from the ultimate do it yourselfer and I know how to do it both ways.

Regards

cww
 
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