How to read analog signals?

**thm ov3rkill** · - 24th February 2009, 00:23

well joe thanks for replying what I want to do is... I want to be able to test a analog voltage peroid. And if that analog volatge is in fat true then I want it to pulse low out of the same pin testing that voltage.

edit i dont want to see how much the voltage is i want to see when it read analog

**LinkMTech** · - 24th February 2009, 01:46

edit i dont want to see how much the voltage is i want to see when it read analog

I'm taking a stab at this. I believe when you say "true" you are wanting to say "through", meaning "complete" or "done", is this correct?
And if that is the case, then it can be done but your circuit will have to be made to monitor your analog signal and have an LED at the same pin.
It would be simpler to use one pin for the analog signal input then turn ON an LED on another pin (setup as an output) when the A/D is completed or "through".

**Archangel** · - 24th February 2009, 06:36

Originally Posted by thm ov3rkill

I want to be able to test a analog voltage peroid.

Ok you want to test an analog voltage, what are you testing for? Do you mean any value greater than zero ?

And if that analog volatge is in fat true then I want it to pulse low out of the same pin testing that voltage.

edit i dont want to see how much the voltage is i want to see when it read analog

So if I understand correctly . . .

Code:

 
If voltage is > 0 then
PortA.0 = 0 'set port latch to low status before enabling tris
TRISA.0 = 0 ' Turn input into output enabling port to pull low.
else
TrisA.0 = 1 ' Keep port in high impedance input status
endif

Where PortA.0 in this example is your analog input / output port

**thm ov3rkill** · - 25th February 2009, 03:50

Hey joe Well this is the thing I want to setup a little project . You may remmeber me from the xbox 360 thread. But i didint get a chance on that. So i wanted to seeif i can acually get to read the trigger press and pulse out.

Also I wanted this to be done on a pic 12f683

Well The reason i want it on the same pin because I dont think i can kill 2 birds with one stone meaning as There is only on spot to read and fire of the controller which is called the wiper. I have seen this done before. So lets say i pull the trigger the pic reads the analog then it pulses low.

**Archangel** · - 25th February 2009, 04:20

Originally Posted by thm ov3rkill

Hey joe Well this is the thing I want to setup a little project . You may remmeber me from the xbox 360 thread. But i didint get a chance on that. So i wanted to seeif i can acually get to read the trigger press and pulse out.

Also I wanted this to be done on a pic 12f683

Well The reason i want it on the same pin because I dont think i can kill 2 birds with one stone meaning as There is only on spot to read and fire of the controller which is called the wiper. I have seen this done before. So lets say i pull the trigger the pic reads the analog then it pulses low.

I did not forget . . . Here is what I am having trouble understanding "i pull the trigger the pic reads the analog then it pulses low" Exactly what do you mean by "the PIC reads the analog", What exactly must it see, to then make the pic pulse low? What state is the pin in when the condition is NOT met ? What state is it in when you want the pic to fire ?

**Acetronics2** · - 25th February 2009, 10:33

Hi Joe,

What I understand here is ...

IF input pin level is LOW, the Pic must Hold The pin LOW ...

Question ( useful ! )

When must the Pic release the pin ???

In clear Words ...

I pull the trigger of my gun ... and I want it to make a machine gun ... instead of single shot.

OR

I Want to transform an astable button into a bistable one ( ? )

Or something like that....

Looks using Comparator offers more Here ... Even if a Timer might be fired ...
12F629 ???

Alain

**thm ov3rkill** · - 27th February 2009, 02:50

hey Thanks ace.

Well again in words. The xbox 360 controller triggers have a analog signal when you press then down thats what it fires off...

so lets say I want to pull my trigger. if the pic reads( or sees what ever you want to call it) the analog signal that just came trough when i pressed the trigger it makes that same pin into a output and starts to pulses low and when i let go of it it stops and just goes back up top^^=].

**LinkMTech** · - 1st March 2009, 22:02

Here's something untested you can try. Two methods of rapid fire but you also need to add a 330 Ohm resistor between the button and the input so the PIC can sense a press then drive the same pin as an output even if you keep holding the button low.
I used the names pulse_fire and rapid_fire just to make them seperate.
If it does work for you, adjust the PAUSE times to suit your needs.

Code:

' This one fires off 5 shots per press or continueously if button held
pulse_fire:                 
    i=0                     ' Reset increment counter
    TRISIO = %00000001      ' Port 0 input, rest outputs
    while GPIO.0=1: Wend    ' Wait here until button pressed
    TRISIO = %00000000      ' Port 0 now an output
        for i=1 to 5        ' Set number of rapid fires per button press
            low GPIO.0      ' Hold output LOW
            pause 50        ' Held LOW for 50ms
            high GPIO.0     ' Turn OFF output
            pause 50        ' Keep OFF for 50 ms
        next i              ' 
goto pulse_fire             ' Go back, continue if button still pressed or 
                            ' wait until pressed again.
                            
' This one just continueously fires as long as button is pushed
rapid_fire:
    TRISIO = %00000001      ' Port 0 input, rest outputs
    while GPIO.0=1: Wend    ' Wait here until button pressed
    TRISIO = %00000000      ' Port 0 now an output
            low GPIO.0      ' Hold output LOW
            pause 50        ' Held LOW for 50ms
            high GPIO.0     ' Turn OFF output                                     
            pause 50        ' Keep OFF for 50 ms
goto rapid_fire             ' Go back, continue as long as button pressed

Here's the schematic to the resistor add on: