multiple switches~one ADC

[naga]

Planning to connect multiple switches into single port.one ADC pin to detect voltage level when each switch for each state is pressed and each switch is associated with a voltage.connecting 8 switches with 1 adc.. Looking for some coding tips.. Thanx.

[mackrackit]

That should work. After you read the ADC have a gosub with some if/thens or case statements to do ??? at a certain ADC reading. Then go back and read the ADC again.

You may want the code to loop around reading the ADC and have the value with out a switch being pressed do nothing.

[Acetronics2]

Hi, Dave

This also works very well with POT command ( no ADC required ) ... a well known STAMP Application.

EPE had also published an original design around a 555 ... key pressing generates a Pulse depending on the key pressed ...
Interrupt use to detect keystroke ... nice !

Alain

[mackrackit]

Never cared much for the POT command. Seems not as stable. But that is me.

I am going to look at your other option. Sounds interesting.
Thanks!

[Acetronics2]

Never cared much for the POT command. Seems not as stable. But that is me.

!

Hi, Dave

I generally do not use POT ... but for 10-12 keys or less result is reliable with a reasonnable range of values for each key.

soooo, I do it simple ( for once !!! )

I'll try dig out the EPE Keybd ... it's somewhere in my HDD !!!

Alain

[naga]

Hi All, tried this code, its working but is there any other reliable way....

adval var byte ' Create adval to store result

TRISA = %11111111 ' Set PORTA to all input
ADCON1 = %00000010 ' Set PORTA analog
Pause 500 ' Wait .5 second
loop: ADCIN 0, adval ' Read channel 0 to adval
Lcdout $fe, 1 ' Clear LCD
Lcdout "Value: ", DEC adval ' Display the decimal value
Select case adval
CASE is <51
high porte.0
cASE 102
high porte.1
CASE 153
high portd.2
CASE 204
high portd.3
CASE is >225
low porte.0 : low porte.1 : low portd.2 : low portd.3
Pause 150
END SELECT
pause 100
Goto loop
End
* this below line is not accepting :ERROR
case >1 to <53
'do some thing
case >53 to < 102
'do some thing..
So On.....