Announcement

Collapse
No announcement yet.

Controllable LEDs on Robot

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by 5294-jjkd View Post
    I suspect that driving LEDs in this way will be ruled as not in compliance, I suggest you explicitly outline this scenario for a ruling. There have been a number of questions trying to avoid the requirement to use a core motor controller to control LEDs that are not being wired as always-on to the PDM, and all have been disallowed so far. In addition, a breadboarded custom circuit is also disallowed per RE17.
    Precisely for these reasons with the rules, we think it's not worth it to do LEDs on FTC robots. Like I said, we worry about draining too much power that will affect the performance of the robot just to be pretty.
    Originally posted by 5294-jjkd View Post
    FYI, mikets, splitting power connections is explicitly allowed. A second battery for LEDs is explicitly not allowed. Both of these points are covered either in the game manual or in the rules/questions/answers threads.
    Thanks for the info. I think I read these rules before. That's why I said "I have the impression...". I am just not fluent with the rules enough to quote them.

    Comment


    • #17
      I agree that it's more headache than it's worth for the competitive aspect, but if it gets a few kids to feel like they're tackling a problem and learning something...

      I understand that with the PWM ports the CDM is 'powering' the LEDs, but I still can't see a way around:

      <RE17> Additional Electronics – Electronic devices that are not specifically addressed in the preceding rules are not allowed. A partial list of electronics that are not allowed includes: Arduino boards, Raspberry Pi, relays, and custom circuits.
      Transistor => active component => circuit?

      Comment


      • #18
        This was posted on the official forum back in November. Answer 2 says you can't drive LEDs via the CDIM. (There may be some ambiguity in the word 'driven by CDIM' vs 'controlled by CDIM.' The question asked if LEDs can be connected to the CDIM.)

        Quote:
        Originally Posted by FTC8745
        <RE12> Light Sources states that light sources may be powered by an internal
        battery. Additionally, they may be powered by power ports on the CPDM and or a
        CMCM port.
        Can a light source be powered by a port on the Core ServoController or by a USB
        hub port?
        <RE11> Sensors states that sensors may be connected to the Core Device Interface
        Module. Can Light Sources be connected to the CDIM? For example to control RGB
        LEDs.
        Do Lighting Sources have to be simple? Or is a unified module that can be controlled
        for signaling purposes acceptable? (https://www.adafruit.com/products/2157)
        We are thinking of using something like this as a device for the robot to signal the
        drive team.

        Answer 1: No. Light sources may not be powered via Servo Controller or USB hub
        Answer 2: No. Light sources may not be driven by the CDIM
        Answer 3: The LED backpack module you reference would fall under the category of "Additional
        Electronics" and is not allowed per <RE17>

        Comment


        • #19
          Note: there is a difference between "controlled by" and "powered by". In order to make an LED string to light up, it needs to be controlled AND powered. CDIM can supply the control signal but cannot power it because generally, it doesn't have enough current to power an LED string light. So to power it, you can either powered it by the Core Power module or Motor Controller channels. That's where the big current comes from. Anything else simply doesn't have enough current or risking it being fried (including servo channels).

          Comment


          • #20
            Originally posted by mikets View Post
            Note: there is a difference between "controlled by" and "powered by". In order to make an LED string to light up, it needs to be controlled AND powered. CDIM can supply the control signal but cannot power it because generally, it doesn't have enough current to power an LED string light. So to power it, you can either powered it by the Core Power module or Motor Controller channels. That's where the big current comes from. Anything else simply doesn't have enough current or risking it being fried (including servo channels).
            Yes, I don't think that's the issue here. The blanket 'no additional circuits' RE17 "seems" to outlaw any possibility of doing this.

            Certainly it's not necessary for competition. But watch kids faces when you turn on the LED's on your robot, I can't think of a much easier/better add-on to hook kids. These strips are cheap, easy and prevalent. The GDC would do well to remove the barriers and make them easily usable. Maybe even addressable ones?

            Comment


            • #21
              Has anyone seen any clarification on this?

              Comment


              • #22
                Clarification on what? The questions around using LEDs have been asked in the official Q&A thread a number of times in an attempt to get around the rules as written, and the answer has been 'no' every time. If there's a specific configuration you are considering that would clearly be legal under the rules as written and taking the existing Q&A into account, you should be OK. If you have any doubts, you need to ask an official question.

                Comment


                • #23
                  Originally posted by 5294-jjkd View Post
                  Clarification on what?
                  The original post detailed how to control LED strips with transistors. Obviously they passed inspection, and there was a discussion if this is indeed legal. The clarifications leave room for 'interpretation' otherwise, there wouldn't be this discussion. Kids here would love to use multiple colors for signalling, and had things cross wired, working before that was explicitly disallowed. If they're allowed to use transistors or diodes to do this, they'd like to.

                  Comment


                  • #24
                    I would suggest that it is not obvious that they passed inspection, nor known whether if they had indeed passed inspection as to whether that was a league inspection or a qualifier inspection, nor obvious that if they passed that inspection, whether they told the inspector that they had this feature implemented in this way on their robot. Not all inspectors are sufficiently well versed technically to make this kind of distinction (which could be its own discussion thread). Nor is it clear how they answered the question that refers to RE12 on the robot self-inspection report. I also see no statement earlier in the thread indicating that they had passed a formal inspection with this on their robot. Even if they have, any decision made there at that event (right or wrong) is not binding on any future event.

                    Again, if you are looking for an official ruling on this, you need to ask an official question as indicated here: http://ftcforum.usfirst.org/showthre...Guidelines-*** Anything less is not binding on anyone anywhere. Otherwise, anything asked or answered here or anywhere else, including at an event, is only opinion. My opinion is that the powers-that-be have indicated that anything other than the specific narrow applications already approved would not be an accepted approach for this season, based on the questions and answers previously asked in the official Q&A forum and the existing rules. If you can get a ruling otherwise, great. Some of the people on my team also would like to add some LED bling to the robot, so I would not mind at all being proved wrong here.
                    Last edited by 5294-jjkd; 01-26-2017, 04:19 PM.

                    Comment


                    • #25
                      They did indeed ask ~2 weeks ago, thought maybe we had missed something. I agree that the transistor circuit shouldn't pass RE12 but have thought differently than the GDC on several occasions. Diodes are considered passive electronics so I could envision a scheme using only diodes & motor controllers to control colors on common cathode strips, but not sure if that would still be considered 'cross wired'.

                      I suppose we could wire three different color strips to three different motor ports. I don't see the need for a road block here, but would like to know either way.

                      Comment


                      • #26
                        ... but would like to know either way.
                        Then you need to ask an official question using the official process.

                        Wiring three different color strips to three different motor ports would comply with the documented rules and restrictions, as far as I can tell. I believe that there was a ruling that using a current-limiting resistor separate from an LED was allowed. Yes, here it is. Asking if a diode in series with one or more LEDs connected solely to a single motor controller (or to a single port on a motor controller) would be allowed could be asked as an extension of that ruling, and I would think at least has a chance of being allowed. I doubt that making electrical connections to more than one motor controller which end up connecting to a common circuit is likely to get through, as it was explicitly disallowed in the same question that resulted in the current-limiting resistor answer linked above.
                        Last edited by 5294-jjkd; 01-27-2017, 09:33 AM. Reason: added link to referenced Q&A

                        Comment

                        Working...
                        X