Let's talk about motor controllers

When I think about motor controllers I like to break them up into three categories based on their capabilities. High, medium, and low levels of “intelligence”, all relative to each other. The controllers with ***** next to their names are ones I have never actually worked with but I have read the docs on them. I would love to hear what others have to say about them. That’s the reason for this post. I’m adding my thoughts on the rest so that it may be useful to some people just starting out.

I feel as if the only controller worthy of the high category is the Talon SRX. Those who know me know that I love the SRX. It has a whole library of functions dedicated to it since wpilib '17 edition. It has a $89.99 price tag but if you know how to use these you can save yourself a ton of work. The data port has capabilities for limit switches and encoders and more (I believe). There’s more to it but it starts to get above my pay grade when we start talking about motion profiling :smiley: (some day)

In the medium category I’ll put the Spark, Jaguar, and the SD540B/C*. They all have built in limit switches. The Spark’s do not require programming and I think that the SD540’s don’t require anything in your code but you configure them in the configuration tool for the controller. The documentation for the SD540 is a bit decentralized for me so I may be not reading that well. But the SD540 has encoder input too which is cool. How that works I could not find, but it exists. The Jaguar has this stuff too. It’s just that it’s $79.99 price tag, being discontinued, and the fact that I have literally never heard a good thing about it doesn’t help it hahaha :D. The Spark is $45.00 and the SD540 is $49.00. But what I have heard about the SD540 from others is not great. If anyone has any experience with it I’d really appreciate a response :slight_smile:

In the low category we have every other FRC legal controller. This includes the DMC 60*, Talon/Talon SR, Victor 884/888, and Victor SP. The Talon/Talon SR, and Victor 884/888 being discontinued does not help their case here but they are still legal and I know that 1257 has a few of each of those still sitting in our shop. The DMC 60 is self proclaimed to be “electrically and mechanically compatible with the Victor SP motor controller” so it’s a clone that at a $69.99 price is $10.00 more than what it is trying to replicate. Who would have thunk it. And I don’t fully understand the appeal of the Victor SP either. It is no better than a Spark I don’t think. Personally, I’d rather have the Spark. I also don’t see the difference from its predecessors (884/888). It’s just a speed controller as far as I’ve been able to find. If anyone uses them primarily I’m interested to know why you chose them over the Spark.

TL;DR Why do you use Victor SPs? Why do you use DMC 60s? What are your thoughts on SD540s?

Thanks in advance :smiley:

For the poll I meant it to be multiple select but oops. So just select the one you use primarily

The Victor SPs came out first. So if you happen to have a stockpile of them when the Sparks came out, it isn’t worth it to switch.

Besides, the Victor SPs are slightly smaller and easier to package. Still, if I had to pick now, I’d choose the Spark.

I didn’t answer the poll, because we currently use SRXs and SRs approximately equally. This year we used SRXs on our drive train and SRs for the manipulators.

I mainly agree; however, I think that, as far as capabilities are concerned, the Jaguars are easily in the same class as the Talon SRX. The Jaguars are also controllable over CAN and PWM, have essentially the same sensor inputs, and support onboard PID. In addition, the Jaguars have externally-accessible JTAG connectors, and TI released a development kit, which means that one can write and upload custom firmware (not legal for FRC, of course). Furthermore, the Black Jags have an RS232-to-CAN bridge, meaning that they can allow a computer to talk to a whole CAN bus. Granted, the Jaguars’ larger form factor and fan cooling (leaving an entry point for swarf) mean that the Talon SRX is preferable for FRC, but for non-competition control systems, the Black Jag is my go-to.

5402 uses a mixture of Talon SRXs when we think we’ll want feedback, and then a mixture of controllers when we know we won’t (climber and intake, for example). There’s a preference for Talon SRXs when we have to purchase new motor controllers going forward, as CAN is a wonderful thing and we’d rather have the flexibility, but we’re not above a Victor SP/Talon SR/SPARK when we have them lying around.

(Full disclosure, Iron Kings are sponsored by and I work for AndyMark that sells or has sold all of those controllers save the SPARK.)

We use the SPARKs since they’re cheap and don’t need fans. If we need PID control, we’ll just code it ourselves.

I should also note that I did a similar survey on /r/frc a few months ago with more detailed responses. Here’s the spreadsheet.

All very interesting. But is there anything about the Victor SP/DMC 60 that could make teams want to buy it over the Spark?

With my vendor hat off and my team leader hat on:

  1. Packaging. Sometimes, a skinnier/taller design is just going to fit better in the robot.
  2. Commonality with SRXs in terms of wiring. If you don’t have to add more terminals to your toolbox (and/or fix those terminals when some kid screws it up), it’s a win.
  3. The Victor SP is pretty widely distributed–Vex, CTRE, WCP, and AndyMark all carry it. So it’s easy to add them to your existing order and not have to get a second order from one of Rev’s channels through your institution’s purchasing process. (How much this is or isn’t an issue depends on the institution.)

We only use SRXs and have since our rookie season. We like them primarily for the existence of CAN - for wiring them in series we can just cut and solder the CAN wires to the perfect length. Direct encoder attachment is definitely a plus, especially because we use the Mag Encoder from CTRE. I’ve seen a few teams using Sparks, namely our friends at 5924 used them this year and I’m pretty certain last year as well.

IMO, the appeal of the Victor SP is mainly the smaller form factor and case design. The DMC is just silly because it’s pretty much an exact copy of the SP.

We actually used all SRXs this year and mixed sparks with SRXs last year. We continue to use sparks for prototype electrical boards for the cost but intend to continue using SRXs for our robots.

In 2014 we bought a bunch of Talons due to size constraints and have been using them ever since.(Budget reasons mostly.) Before that we exclusively used jags.

The Talon SRX’s look fun. Might investigate that for next year.

Oops! I could have sworn I saw at least one in your 2017 robot. But that’s good to know.

There’s more lights on the DMC 60 than any other motor controller.

You right

SPs are also the most efficient motor controller currently on the market (though only marginally more so than the Talon SRX).

If you really need that extra .05v you’re doing something wrong.