Reading analog input

[Transistorman]

anyone know a simple way ?

 

[ericgibbs]

anyone know a simple way ?

hi TT,
This question is very ambiguous, what do you mean....

 

[MikeMl]

anyone know a simple way ?

How about a cheap way?

 

[Transistorman]

hi TT,
This question is very ambiguous, what do you mean....

im trying to make keypad using only one analog port

i want to measure the analog input so i can put the right analog input to my code

i will post my schematic after this post

 

[EngIntoHW]

How about using an ADC?

 

[Transistorman]

here is the schematic

**broken link removed**

 

[ericgibbs]

here is the schematic

**broken link removed**

hi TT,
What do you think the voltage will be on pin 7 when you press either switch.????????

 

[Nigel Goodwin]

hi TT,
What do you think the voltage will be on pin 7 when you press either switch.????????

Not to mention that the 12F629 doesn't have an ADC

If he wants to use the 12F629?, then he could checkout my joystick tutorial, which would allow him to do what he wants.

 

[Transistorman]

hi TT,
What do you think the voltage will be on pin 7 when you press either switch.????????

i dont know

 

[ericgibbs]

i dont know

hi TT,
Use Ohms law.
The input resistance of the analog is VERY high compared to the 1K and 10K resistors.

Current = Voltage/Resistance..... the resistance is the sum of the 1K or 10K with very input resistance..........

So a little test for you, what do you think the current thru the 1K is if the adc input is say 1megohm.....???????

 

[Nigel Goodwin]

So a little test for you, what do you think the current thru the 1K is if the adc input is say 1megohm.....???????

And it's a LOT higher than that.

 

[Transistorman]

Not to mention that the 12F629 doesn't have an ADC

If he wants to use the 12F629?, then he could checkout my joystick tutorial, which would allow him to do what he wants.

sorry , wrong pick

i though it was 12F675

too hurry of making schematic

besides of that

i also have 627 to play with , right ?

 

[ericgibbs]

And it's a LOT higher than that.

hi Nigel
I know that, but I am trying to make the sums easier to start with...............

I dont think TT knows the basic Ohms methods..yet.

 

[Transistorman]

hi TT,
Use Ohms law.
The input resistance of the analog is VERY high compared to the 1K and 10K resistors.

Current = Voltage/Resistance..... the resistance is the sum of the 1K or 10K with very input resistance..........

So a little test for you, what do you think the current thru the 1K is if the adc input is say 1megohm.....???????

i dont understand

so there is a way to calculate analog input ?

 

[Nigel Goodwin]

i dont understand

so there is a way to calculate analog input ?

Look up 'potential divider'.

 

[Transistorman]

Look up 'potential divider'.

ok , i will take a look