Keypad Voltage Programming

[KC4NYK]

Hey John,

Thanks again for the germanium diode!! It will sing later today! For now I remembered your question about replacing a rotary switch with a numpad or other button-based solution and found this - http://www.technoblogy.com/show?NGM. This can all be programmed on an ATtiny or ATtiny85 - I think I have both somewhere if you don't have. Anyway it's like I said - agrid of resistances with a whopping 28 ohms between the various button values and a simple comparator script in the ATtiny will then identifiy the button pressed.

The resistor ladder is connected to the analogue input A2 on an ATtiny85. Here they are using a serial seven-segment display to display the key pressed; this is interfaced to three pins on the ATtiny85, using Jack Christensen's tinySPI interface - but the output could be sent to any device.

keypadVoltageInterface.png

ATtiny85_DataSheet.png

Hope this gets you down the road a bit.

Cheers,

Rob T…login to view the rest of this post