How to connect multiple buttons to a single microcontroller pin using resistor matrix?

How can i control a lot of buttons by a single pin of microcontroller?

If pin of ADC, then via the R-2R ladder.
Like this:
http://dduino.blogspot.com/2012/03/buttons-r2r-resistor-ladder.html
http://en.wikipedia.org/wiki/Resistor_ladder

you can make easily make a circuit by voltage divider method so that as soon as the key is pressed the MCU will read a voltage surge and the
voltage surge mapped to the button pressed.
suppose a key pad(hypothetical) with 11 keys
5/12 = 0.4167 volt per step

so 0.4167 V== "1"
0.8333== "2"........
12.00 -0.4167=="#"

all we will need is gnd/5V and analog input pin to read voltages and off-course resistors.
In this way we can accomplish task by only one pin.

You can see a schematic of a series of pushbuttons and resistors feeding a single analog input here - "http://www.dfrobot.com/image/data/DFR0009/DFR0009SCH01.pdf(resistor ladder)":http://www.dfrobot.com/image/data/DFR0009/DFR0009SCH01.pdf

The Arduino code to use them here - "http://arduinotronics.blogspot.com/2012/06/lcd-keypad-shield.html(resistor ladder code)":http://arduinotronics.blogspot.com/2012/06/lcd-keypad-shield.html

It is being assumed here that you actually mean,

"How can I control a microcontroller from a lot of buttons, all having different functions, but all connected to the same pin."


Just to check, is that correct ?

Hi Michael

See below for notes on this page 10 Lots of other hints about various methods which are usefull when programming interfacing Pic micro Chips