Can anyone help me wire a Raspberry Pi to a Schwinn elliptical trainer?

[Gordon Myers]

I was wondering if there is anyone in Sector 67 with a knowledge of electrical engineering and/or reverse engineering who might be willing to help me with a project. I have a Schwinn 420 elliptical trainer, and ultimately I want to replace the console that controls it, with a Raspberry Pi. I have a couple of different motivations, including wanting more control, and wanting a smaller physical console. But I have basically zero knowledge of electrical engineering and circuits. I do have expert knowledge of software engineering though, so if I can figure out the right "signals" to send from the Pi, I can build a nicer UI for it, or maybe a REST interface and then even control it from an Echo Dot, and so on.

The existing console seems to be a simple PCB with a LCD display. It is connected to the main unit by a 12-pin jumper cable (see attached). My thought is that if I can figure out how each of those 12 wires work, I could connect them to the GPIO pins of a Raspberry Pi and control things from there. I imagine I'd have to use something like a multimeter, or an oscilloscope, and essentially "eavesdrop" on the different wires while the machine is running. But like I said, I have very little knowledge of wiring so I'm not really sure where to start. Would I want to test voltage? Or current? Or maybe both? How do I go about testing that sort of thing? These are the kinds of questions I would have.

I would certainly be willing to truck the machine over to the Sector 67 space, if there's someone there who has a little time to help me with this project. I was also hoping to use it as a bit of an educational experience. So if we actually got everything working, I'd like to write up a blog post about the experience. But perhaps I'm getting ahead of myself. Is this something anyone here might be qualified to help out with?

[Jeff Whitehouse]

It seems to me that controlling an elliptical trainer from an Amazon Echo dot is a bit,,,,, odd. "Alexa, start my elliptical trainer." "Alexa, do my morning  elliptical workout."

--
You received this message because you are subscribed to the Google Groups "Sector67 Public" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sector67+u...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Gordon Myers]

I don't think it's that odd, if you have a couple of pre-programmed workouts, and don't want to set up a screen. "Alexa, start a difficult workout for 45 minutes."

But in any case, my point in mentioning the software part was only to say that the sky's the limit, once we understand the lower-level "protocol." With only 12 wires and the simple nature of the machine, I have to imagine there are really only three or four things being transmitted over those wires (increase resistance, decrease resistance, is someone running?, and power).

[Gordon Myers]

Hmmm, I got an email from this group, asking if I could find a Service Manual for the elliptical, but now for some reason I don't see that posted here. I'm not really sure how Google Groups work.

In any case, the short answer is, unfortunately, no. There aren't any service manuals available. I've checked. Here's the longer answer:

The Schwinn website no longer lists any manuals (service or otherwise) for my model, the 420. A third-party website shows there is an Owner's Manual as well as an Assembly Manual for the 420, but no Service Manual. I found a similar model (the 426) which does have a Service Manual on that same third-party website, but unfortunately it says hardly anything about the wiring. In fact, the only thing it says is "Check data cable integrity. All cable wires shouldbe intact. If any are visibly crimped or cut, replace the cable." So not very helpful, unfortunately. I also emailed Schwinn last week asking for a more descriptive Service Manual, but they said they didn't have one and recommended various repair shops (they assumed I was asking for one for repair purposes).

[Kyle Mayer]

How committed are you to using the built in display? It’d be ultra easy to interface with the machine and bring your own lcd or oled display- pick your flavor, there’s a million out there. (Or heck, a full blown monitor if you’re running on a pi). Of course, the built in one has the correct form factor and a premade housing . . . There are a couple of different standards for communicating with an lcd, assuming the lcd has its own driver chip. For character lcds, there is a common one that is 14-16 signals depending on whether or not there is a backlight. What does the screen look like while on? Is it just a character display or a full x by x pixel display with custom graphics? Can you find a black IC somewhere on the lcd circuit board, probably 48-64 pins?

I’m a local electrical engineer, I’ll be out of town this weekend, but I’d be happy to spend a few hours kicking around some electronics next week- either identifying what protocol they are using or setting you up with a new screen altogether. If they aren’t using one of the standard protocols though it could be pretty hopeless- just ‘spying’ on the wires and reverse engineering a 14 wire communication protocol sounds like no fun.

Kyle

[Gordon Myers]

Kyle: it's a character display (see attached). It has a countdown timer, a measurement of speed, RPM, and a visualization of how high the resistance is currently set. Some of that information (e.g. the countdown timer) is totally internal to the console, meaning it wouldn't have to transmit anything over the wires back to the base machine. Other information, like RPM, is surely transmitted on one or more of those wires.

Just so I understand, what exactly are you proposing? That I remove the existing PCB from the plastic casing, and use that to drive everything? In any case, I'd love to take you up on that offer to spend a few hours on it, perhaps two weekends from now.

Best,

Gordon

You received this message because you are subscribed to a topic in the Google Groups "Sector67 Public" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/sector67/rSxHXWNiSjo/unsubscribe.
To unsubscribe from this group and all its topics, send an email to sector67+u...@googlegroups.com.