Go to Post I am specifically looking for Rhode Island, Hawaii, New Hampshire, Nevada, California, Florida, ... oh heck, all of the rest. - Rosiebotboss [more]
Home
Go Back   Chief Delphi > Technical > Programming
CD-Events   CD-Media   CD-Spy   FRC-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 04-20-2005, 09:33 AM
stephenthe1 stephenthe1 is offline
Registered User
#1008
 
Join Date: Dec 2004
Location: Ohio
Posts: 113
stephenthe1 is on a distinguished road
limit switches

Hi,
We've been having a little trouble using limit switches. We get the value registered when the limit switch is pressed, but when it is released, the value doesn't change back. I figured the first thing to check would be the wiring. I haven't seen much on chiefdelphi after searching on limit switches, so if you could provide a wiring diagram, that would be helpful. Then secondly, maybe sample code for referencing the limit switch. ThankS!
-Stephen P.
  #2   Spotlight this post!  
Unread 04-20-2005, 11:41 AM
Unsung FIRST Hero
Mike Betts Mike Betts is offline
Electrical Engineer
no team
Team Role: Engineer
 
Join Date: Dec 2001
Rookie Year: 1995
Location: Homosassa, FL
Posts: 1,443
Mike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond repute
Re: limit switches

As per page 9 of the "Full Size RC Reference Guide", switches are connected between SIG and GND on the digital input.
__________________
Mike Betts

Alumnus, Team 3518, Panthrobots, 2011
Alumnus, Team 177, Bobcat Robotics, 1995 - 2010
LRI, Connecticut Regional, 2007-2010
LRI, WPI Regional, 2009 - 2010
RI, South Florida Regional, 2012 - 2013

As easy as 355/113...
  #3   Spotlight this post!  
Unread 04-26-2005, 09:11 AM
stephenthe1 stephenthe1 is offline
Registered User
#1008
 
Join Date: Dec 2004
Location: Ohio
Posts: 113
stephenthe1 is on a distinguished road
Re: limit switches

we're having a big problem with our limit switches. Basically, once it is pressed, the value of it changes it to 1, which is good, but once it is released, it doesn't change back to 0. hilf mir! danke schon
  #4   Spotlight this post!  
Unread 04-26-2005, 09:34 AM
billbo911's Avatar
billbo911 billbo911 is offline
Registered User
AKA: That's "Mr. Bill"
FRC #2073 (EagleForce)
Team Role: Mentor
 
Join Date: Mar 2005
Rookie Year: 2005
Location: Elk Grove, Ca.
Posts: 1,806
billbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond repute
Re: limit switches

Quote:
Originally Posted by stephenthe1
Hi,
We've been having a little trouble using limit switches. We get the value registered when the limit switch is pressed, but when it is released, the value doesn't change back. I figured the first thing to check would be the wiring. I haven't seen much on chiefdelphi after searching on limit switches, so if you could provide a wiring diagram, that would be helpful. Then secondly, maybe sample code for referencing the limit switch. ThankS!
-Stephen P.
A couple of questions, or answers to them, might help:
1) How are the switches connected? For example: Are they connected to the RC Digital input 1, 2, 3 etc.
2) How are you "registering them"? Do you have your own code, or are you using the interrupts associated with the digital inputs?
3) When it sticks, how do you unstick it? Manually or by reseting the controllers?

If you are using the digital inputs, my guess is that the switches are sticking, either by binding of the mechanism, or internally to the micro switch it's self. If you are using your own code to set a flag, the code may not be written to reset the flag once the switch state changes.

Good Luck, and let us know what you find.
  #5   Spotlight this post!  
Unread 04-26-2005, 02:53 PM
Ryan M. Ryan M. is offline
Programming User
FRC #1317 (Digital Fusion)
Team Role: Programmer
 
Join Date: Jan 2004
Rookie Year: 2004
Location: Ohio
Posts: 1,508
Ryan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud of
Re: limit switches

Quote:
Originally Posted by billbo911
If you are using the digital inputs, my guess is that the switches are sticking, either by binding of the mechanism, or internally to the micro switch it's self. If you are using your own code to set a flag, the code may not be written to reset the flag once the switch state changes.
I bet he's right. Try hooking a multimeter up to the switch and see how the resistance changes when you press and release the switch. If it's working properly, you should see a high (infinite, depending on the meter) resistance when released, followed by a fairly low resistance when you press it, and back to what it was before when you release it again.

If you find that it stays low after you release the switch, then you know it's the switches fault. Get a new one...
__________________

  #6   Spotlight this post!  
Unread 04-26-2005, 04:29 PM
stephenthe1 stephenthe1 is offline
Registered User
#1008
 
Join Date: Dec 2004
Location: Ohio
Posts: 113
stephenthe1 is on a distinguished road
Re: limit switches

I think the switch is ok. The problem is, once pressed, the value I use to reference it in the code (rc_dig_in08 == 0) when it is released, does not recognize that it is released. It recognizes in the code when it changes to one, though (rc_dig_in08 == 1) when it is pressed, but upon release, it doesn't change back to zero. Would this be code, I don't think so anyways, but I have my doubts as to whether it is hardware, because my code is such that the motor should only turn if the rc_dig_in08 == 0, and once the switch is released, and I press the button to turn the motor, it acts as if the rc_dig_in08 did indeed return back to 0, it's normal state. This really perplexes me. If you want to see my code, just respond and ask and I'll show you, it's very simple. My Mentor thinks it's possible we have a limit switch, that remembers its state, and upon release of the switch, it stays that way instead of returning back to it's 0 state. I hope this made sense, if not (I'm slightly confused myself!), I'll post the code, and will try to provide wiring details on our limit switch on Thursday. Thank you for you help!
  #7   Spotlight this post!  
Unread 04-26-2005, 04:46 PM
Alan Anderson's Avatar
Alan Anderson Alan Anderson is offline
Software Architect
FRC #0045 (TechnoKats)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Kokomo, Indiana
Posts: 7,731
Alan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond repute
Send a message via AIM to Alan Anderson
Re: limit switches

Quote:
Originally Posted by stephenthe1
...the value I use to reference it in the code (rc_dig_in08 == 0) when it is released, does not recognize that it is released. It recognizes in the code when it changes to one, though (rc_dig_in08 == 1) when it is pressed, but upon release, it doesn't change back to zero...
If you have the switch wired properly, between SIG and GND, the digital input will read 1 when the switch is open, and 0 when the switch is closed.

Please post the part of the code that isn't doing what you expect it to do.
  #8   Spotlight this post!  
Unread 04-26-2005, 05:34 PM
Mike's Avatar
Mike Mike is offline
has common ground with Matt Krass
AKA: Mike Sorrenti
FRC #0237 (Sie-H2O-Bots (See-Hoe-Bots) [T.R.I.B.E.])
Team Role: Programmer
 
Join Date: Dec 2004
Rookie Year: 2004
Location: Watertown, CT
Posts: 1,003
Mike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond repute
Re: limit switches

Try adding a printf to your code, see what it puts out.

printf("Limit Switch: %f \n", rc_dig_in08);
__________________
-Mike
  #9   Spotlight this post!  
Unread 04-26-2005, 11:29 PM
Alan Anderson's Avatar
Alan Anderson Alan Anderson is offline
Software Architect
FRC #0045 (TechnoKats)
Team Role: Mentor
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Kokomo, Indiana
Posts: 7,731
Alan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond reputeAlan Anderson has a reputation beyond repute
Send a message via AIM to Alan Anderson
Re: limit switches

Quote:
Originally Posted by MikeWasHere05
printf("Limit Switch: %f \n", rc_dig_in08);
I thought the printf() we have didn't support the %f format. Even so, you want %d anyway.
  #10   Spotlight this post!  
Unread 04-27-2005, 12:42 AM
David Brinza's Avatar
David Brinza David Brinza is offline
Lead Mentor, Robot Inspector
FRC #0980 (ThunderBots)
Team Role: Mentor
 
Join Date: Feb 2003
Rookie Year: 2003
Location: Glendale, CA
Posts: 1,270
David Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond reputeDavid Brinza has a reputation beyond repute
Re: limit switches

Quote:
Originally Posted by stephenthe1
we're having a big problem with our limit switches. Basically, once it is pressed, the value of it changes it to 1, which is good, but once it is released, it doesn't change back to 0. hilf mir! danke schon
Make sure you're using a "momentary contact" switch rather than a latching or locking switch. The momentary contact switch will only remain closed/open while the switch is depressed, whereas a latching/locking switch toggles between open and closed each time the switch is depressed.
__________________
"There's never enough time to do it right, but always time to do it over."
2003 AZ: Semifinals, Motorola Quality; SoCal: Q-finals, Xerox Creativity; IRI : Q-finals
2004 AZ: Semifinals, GM Industrial Design; SoCall: Winners, Leadership in Controls; Championship: Galileo #2 seed, Quarterfinalist; IRI: Champions
2005 AZ: #1 Seed, Xerox Creativity; SoCal: Finalist, RadioShack Controls; SVR: Winners, Delphi "Driving Tomorrow's Technologies"; Championship: Archimedes Semifinals; IRI: Finalist
2007 LA: Finalist; San Diego: Q-finals; CalGames: Finalist <-> 2008 San Diego: Q-finals; LA: Winners; CalGames: Finalist
2009 LA: Semifinals; Las Vegas: Q-finals; IRI: #1 Seed, Finalist <-> 2010 AZ: Motorola Quality; LA: Finalist
2011 SD: Q-finals; LA: Q-finals <-> 2013 LA: Xerox Creativity, WFFA, Dean's List Finalist <-> 2014 IE: Q-finals, LA: Finalist
  #11   Spotlight this post!  
Unread 04-27-2005, 11:28 AM
Greg Ross's Avatar
Greg Ross Greg Ross is offline
Grammar Curmudgeon
AKA: gwross
FRC #0330 (Beach 'Bots)
Team Role: Mentor
 
Join Date: Jun 2001
Rookie Year: 1998
Location: Hermosa Beach, CA
Posts: 2,244
Greg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond reputeGreg Ross has a reputation beyond repute
Send a message via AIM to Greg Ross Send a message via Yahoo to Greg Ross
Re: limit switches

If I were a betting man, I would put money on it being a software problem.

First check the switch -- only because it's often easier to check hardware than to find a code problem. If it tests OK, then it is more than likely a software problem. (It could still be the controller, but unless you had a fairly major oopsie with it, I doubt it.)

After you've tested the switch, post the code, and we'll help you find the problem.
__________________
Greg Ross (The Grammar Curmudgeon formerly known as gwross)
S/W Engineer, Team 330, the Beach 'Bots
<--The Grammar Curmudgeon loves this cartoon.
ôLife should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!" Hunter S. Thompson
"Playing a practical joke means doing something mean and calling it funny." Me
  #12   Spotlight this post!  
Unread 04-27-2005, 04:37 PM
Workaphobia Workaphobia is offline
Registered User
AKA: Jon
FRC #1546 (Chaos Inc.)
Team Role: Alumni
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Long Island
Posts: 26
Workaphobia will become famous soon enough
Re: limit switches

This is definitely a simple matter of testing for the wrong value in code. Digital inputs on the RC (but not on the OI) have "pull ups", which means they are set to register as 1 in software when not grounded. Your input will be in the 0 state when the switch is pressed. This isn't a problem at all, just invert where you have tests for 1s and 0s.
  #13   Spotlight this post!  
Unread 04-27-2005, 04:51 PM
stephenthe1 stephenthe1 is offline
Registered User
#1008
 
Join Date: Dec 2004
Location: Ohio
Posts: 113
stephenthe1 is on a distinguished road
Re: limit switches

actually, limit switches are the opposite of that. They are normally 0, or true, then once pressed, turn to 1. I'm trying to find the code I used, but I think it's on my flash drive some where where I can't fine it. I'll post tomorrow with results and code. Thanks for all the help!!!

or wait, do you mean that they've actually 'simplified' it for us, by reversing the values in the code we work with, so I should use == 1 to test for being pressed? that would make a lot of sense, because I thought the joysticks were supposed to be == 0 when pressed, but it only worked when I did == 1. thanks for the information. Why don't they tell people these small, but important things. Thanks!

Last edited by stephenthe1 : 04-27-2005 at 04:55 PM.
  #14   Spotlight this post!  
Unread 04-28-2005, 01:04 AM
Workaphobia Workaphobia is offline
Registered User
AKA: Jon
FRC #1546 (Chaos Inc.)
Team Role: Alumni
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Long Island
Posts: 26
Workaphobia will become famous soon enough
Re: limit switches

Er, unless I'm severely mistaken, it's ==0 for when a digital input is grounded, ==1 for when it's not grounded, ==0 for an unpressed joystick button, and ==1 for a pressed joystick button. Unless your switch grounds when inactive and removes the contact when it's activated, you do test for ==0 (or !rc_dig_in01) to tell when the switch is active. Page 14 of the 2004 Programming Reference Guide describes it.

Actually, it appears that the guide makes no exception for the OI inputs, so perhaps it's possible that the joysticks that we typically use *are* of the second kind of switch, that breaks a ground connection instead of establishing one.

The 2005 OI Guide mentions on page 5 that an OI digital input senses a ground connection to "become active".

Ok, so I'm beginning to doubt some of what I've said, but I'm still fairly certain that the RC switch is logically true in code when ungrounded.
  #15   Spotlight this post!  
Unread 04-28-2005, 06:12 AM
Ryan M. Ryan M. is offline
Programming User
FRC #1317 (Digital Fusion)
Team Role: Programmer
 
Join Date: Jan 2004
Rookie Year: 2004
Location: Ohio
Posts: 1,508
Ryan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud ofRyan M. has much to be proud of
Re: limit switches

Quote:
Originally Posted by Alan Anderson
If you have the switch wired properly, between SIG and GND, the digital input will read 1 when the switch is open, and 0 when the switch is closed.
Quote:
Originally Posted by workaphobia
Your input will be in the 0 state when the switch is pressed. This isn't a problem at all, just invert where you have tests for 1s and 0s.
Quote:
Originally Posted by stephenthe1
actually, limit switches are the opposite of that. They are normally 0, or true, then once pressed, turn to 1.
Quote:
Originally Posted by Workaphobia
Er, unless I'm severely mistaken, it's ==0 for when a digital input is grounded, ==1 for when it's not grounded, ==0 for an unpressed joystick button, and ==1 for a pressed joystick button.


I can never remember/am never sure which it is, so I setup #defines at the beginning of a include file I put all that general setting stuff in, then use that in my tests. IE:
PHP Code:
#define SWITCH_ON 1 /* Value switches give when on. */
#define SWITCH_OFF !SWITCH_ON

if(rc_switch_01 == SWITCH_ON)
{
    
// ...

That way, if I'm wrong, I have to change one value and my entire program changes to reflect it. Plus, it makes your logic (to some people) clearer.
__________________


Last edited by Ryan M. : 04-28-2005 at 09:10 AM. Reason: Missed my closing code tag
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Common Ground on Limit Switches Gary Bonner Electrical 4 02-18-2005 12:24 PM
Robot Controller File Size Limit ?? RoboGeek Programming 1 01-17-2005 06:59 PM
material cost limit haverfordfords Fundraising 3 12-06-2004 06:21 PM
Limit Switches help. Xufer Programming 9 04-21-2004 08:21 PM
Need help with custom switches archiver 2001 3 06-23-2002 11:35 PM


All times are GMT -5. The time now is 09:29 AM.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi