Electrical Issue: PIC input false triggering, Signal Noise suspected.

[Heckler]

abecker,

I think your getting some excellent advice here. As I have said before there are world class programmers here (and also those knowledgeable in electronics design) and all are willing to help.

For all this good advice I think you might owe us some pictures of your train setup and all that
Having a train that actually has an catenary that actually works sounds pretty awesome!
What a fun world to live in, down at the miniature level.
And merging micro controllers and PIC BASIC... what could be better.

You might consider wiring up a length of 6 conductor ribbon cable to the ICSP header then solder it up to a 6 pos header to plug your pickit into.
that way you can easily impliment code changes without having to tear things apart.

Nothing better than to be able to make code changes and test ideas out and see almost instant results.

great stuff!!

now if you have a few minutes check out this...
http://hackaday.com/2016/01/17/the-s...ur-wunderland/
It is awesome to go to google earth and get down in minature and roam around this model setup.

[abecker]

Heckler,

I first discovered this thread by looking at a print ready version of the tree.

My trolley system is at the beginning stages but all the track and overhead is assembled and in good working order when run manually.

I am not at home now but I will send some photos of the table and the controller.

I agree the advice has been very generous and I received more feedback than I expected. I would hope this thread is of use to others in the future with similar designs.

[abecker]

Voila! Photos as promised.

I have yet to provide the scenery work but first things first- get it operating. Manual operation works as designed.

The power (0-17vDC) from the speed control can be routed for overhead supply or to the tracks only by a manual switch. The yard turnout can be operated manually or via the PIC logic.

Controller has an LCD and three buttons to program number of trips, seconds at east and west (future) stations or yard termination. Prompts for setting automation are displayed on LCD.

I made the enclosure out of acrylic sheet so I could custom size it and intended to paint it gray but since it looks pretty cool as a transparent case I think I'll leave it that way.

[Amoque]

No offense, but I hope you are forced back here regularly as this build progresses. I would love to feel (in some small FREE way) that I had helped to make it come together. I've seen many genius level projects here, but my favorites are always those where knowledge is applied to passion.

[abecker]

No offense taken.

Nobody has ever accused ME of being a genius but my tenacity has lead me to many learning opportunities.

I will try several of the strategies offered by the contributors and hopefully if the problem gets resolved soon, I will report back.

[richard]

I discovered this curious method of debounce/noise filtering on the arduino forum this week . the idea translated to pbp easily and makes my worst cheap and nasty tactile switches perform as smooth as silk.
here is a little demo (might add there is no cap used at all on the switch )

'****************************************************************
'*  Name    : debounce.BAS                                      *
'*  Author  : richard                   *
'*  Date    : 2/17/2016                                         *
'*  Version : 1.0                                               *
'*  Notes   :  pic16f1825                                       *
'*          :   switch debounce                                 *
'****************************************************************
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_OFF  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF            
#ENDCONFIG
 
OSCCON=$70 
DEFINE OSC 32
ANSELA=0
ANSELC=0
TRISA = %011010
TRISC = 0 
 
 
led1 var lata.5    ;  lit when  sw operated
led2 var lata.2    ; toggle when sw   operated
sw var porta.3     ;  the switch (active low ie has pull up resistor)
old_sw_state var bit
sw_state var bit
sw_buff  var byte
clear

main :
    gosub ck_sw
    if  sw_state != old_sw_state then   ; the sw has changed either on or off
        led2 = !led2
        if !sw_state then led1 = !led1      ; if state is changed to on
        old_sw_state=sw_state            ;remember state
    endif
goto main

ck_sw:
    sw_buff= (sw_buff<<1) | sw
    if (sw_buff=$7f ) and sw then
       sw_state=1
    elseif  (sw_buff=$80 )and !sw  then
            sw_state=0
    endif
return

[abecker]

Hi Richard,

This a very interesting strategy and I have added it to my collection of code snippets.

On this project my approach is to try the hardware methods first since they (like ground shielding the signal line, etc.) are just good practice anyway. If that doesn't do the trick I will try some of the software solutions. I hope this method will be a way to somewhat isolate the cause of the false triggering or at least give an idea what might be going on.

This project has even forced me to get out my really old and clunky oscilloscope and get some new probes for it. Now I just have to figure out how to set it up to check for noise on the signal line. I'm a bit rusty on using the scope for diagnostics. It's been quite a while since my last class in EE.

Thanks for your thoughts,
Allan

[mark_s]

There are a lot of good suggestions here. One possible cause could be a magnetic field being set up by current passing through the rails.
This could be causing the reed switches to randomly close. Or magnetic coupling into the long leads. Google "Right Hand Rule"

It would be easy to test. Leave everything connected as is, but move the reed switches a few inches away from the tracks.

Hope you figure it out