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New idea about using keyboard and micros

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arash_micro

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New idea about keyboard

Hi
I have an idea about using keyboard and micros
I have use 12 buttons and 13 resistors but only one port
of my micro
Pleas see my (dsn) and tell me my errors.
Does any one use this way.
Thanks
 

Re: New idea about keyboard

There is no .sch file in the attached bunch.
Skimming through the files gave me the idea that the keyboard is read as the voltage dependent on the resistors connected via the selected key, right ?
This kind of keyboard solution was employed in the H3660 iPaq device and worked fine as far as I am concerned.
Regards , yego
 
Re: New idea about keyboard

please reattach the schematic, from reading the attached files you are employing ADC to read the voltage level given out by different keys.
 

New idea about keyboard

sorry for my big mistake
I was sleepy
I have correct the error

Added after 29 minutes:

Hi yego
what is H3660?
 

New idea about keyboard

Couldn't open the schematic. Anyway the design have been used before and also there is a version that use a 555 timer and diferent RC constants for each key. Micro use a timer for frequency measuring instead of ADC port. But there is a problem in both designs: How you deal with two keys (or more) press at the same time? Something can go really wrong (start a motor for example, or open a valve, depends on what your doing with your micro) if you interpret that as a valid key diferent then the two others pressed.
 

Re: New idea about keyboard

Hi,

the H3660 is the PDA called iPAQ made once upon a time by Compaq ( HP at present ). That was just one of several models sharing that feature.
They simply connected the resistor ladder to the AD converter of the AVR controller and measured the input voltage, thus reasoning of the keyboard activity. Now they dropped the idea for some other solutions.

Regards, yego
 

New idea about keyboard

but with this way we can use many button with
using just one port without any scan.
 

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