**** BEGIN LOGGING AT Tue Jan 14 03:00:09 2020 Jan 14 03:10:14 Hello all Jan 14 15:44:43 hello Jan 14 15:48:06 tip: just "hello" is unlikely to get a response here. if you have a question just ask it, and have patience. there are plenty of knowledgeable people here but most only glance at chat occasionally Jan 14 15:53:37 haha can do. not in a rush either, so i'm not demanding an answer quickly. more just checking if there's a way to read (2) 4 wire rotary encoders with a single beaglebone black Jan 14 15:53:42 can't find good documentation on doing that Jan 14 15:54:42 now that totally doesn't sound like a problem Jan 14 15:54:58 indeed it doesn't, even though I'm not sure what a 4-wire rotary encoder signal looks like Jan 14 15:55:14 it that like encoding an abslute position in 16 steps or such? Jan 14 15:55:18 *absolute Jan 14 15:56:24 (gray-coded presumably in that case) Jan 14 15:57:34 oh, or do you just mean quadrature-encoded + power and ground? Jan 14 15:57:43 it's a 2 wire differential quad encoder Jan 14 15:57:54 sorry, been using rotary encoder with the ME here Jan 14 15:58:09 * 4 wire differential quad encoder Jan 14 15:58:22 I have a/~a/b/~b signals Jan 14 15:59:06 do you have a datasheet or something so I can better understand what this means? Jan 14 15:59:43 does each signal just use a differential pair because it can be really high speed? because that sounds worrisome Jan 14 16:02:26 I will find you the datasheet, hold on a second Jan 14 16:02:36 the bbb has three quadrature inputs (one of which conflicts with using the video output hence requires disabling hdmi), but they take simple 2-wire (a/b) input, so I'm mostly just trying to understand the electrical side of what you're trying to interface to Jan 14 16:02:54 more inputs could be created using pru if necessary Jan 14 16:03:02 https://www.omc-stepperonline.com/download/17HS19-1684D-PG5-E1000.pdf this is the motor with the encoder....this is literally all the info I have sadly Jan 14 16:03:13 However, I think I can run them "single ended" and make them a 2 wire encoder Jan 14 16:05:27 an encoder on a stepper motor? isn't that kinda redundant? Jan 14 16:10:01 anyway, in case of unknown or unclear signals, what I'd do is: hook up gnd and vcc (to 3.3v), and either hook the digital signals up to a scope (if available) or to four gpios to check what they're doing, preferably after double-checking that they're indeed just 3.3v digital outputs (e.g. using a multimeter) Jan 14 16:11:40 hmm, they might be using differential signals to suppress noise/spikes resulting from being so close to a motor, in which case there would also be concern about the health of the BBB's digital inputs if you just hook them up directly Jan 14 16:15:19 yeah, "While connecting just the A and B signals is ok in most cases, differential signals are used to minimize the effects of electric noise (inductive coupling, capacitive coupling, etc.) in long electric lines as is usually the case in most machine tools." -- some forum post on the internet Jan 14 16:16:06 so in that case you'd use a dual differential line receiver to convert both signals from differential to single-ended Jan 14 16:21:46 do they make something simple to do that to interface to the BBB? Jan 14 16:22:43 also, iirc it's a 5V encoder Jan 14 16:24:28 seems like this is going to be confusing. using an ni daq right now for it....looking to move to something a bit cheaper Jan 14 16:24:39 lol Jan 14 16:25:32 so find out whether the encoder can run on 3.3v, if not you have to use *some* interfacing electronics anyway, in which case you might as well use a differential receiver Jan 14 16:25:48 i know it's a 5v encoder, just checked. Jan 14 16:26:09 so now i have to go from 5v differential encoder to a 3.3v single ended encoder for the BBB...yay. Jan 14 16:26:21 just a differential line receiver Jan 14 16:26:29 nothing specific to encoder signals Jan 14 16:27:14 i'm still a bit foggy on how all that would plug in then Jan 14 16:27:17 quad differential receivers that run on 3.3v (while accepting 5v input) are easy to find Jan 14 16:27:40 e.g. http://www.ti.com/interface/rs-485-rs-422/products.html#p305nom=3.3;3.3&p2882=0;0&p2881=2;9&sort=p1130;asc Jan 14 16:27:42 you have one in mind for something for me to look at? Jan 14 16:28:18 ah, is there a dev breakout or something for these? Not looking to do a pcb at this point yet Jan 14 16:29:30 there probably is, and otherwise there's always the breadboard option :) using DIY components is a lot cheaper than using an off-the-shelft data acquisition system, but it usually also requires more tinkering Jan 14 16:30:04 i totally agree. Jan 14 16:30:45 so just so i'm clear: 5v diff encoder to 3.3v single ended using quad diff receiver -> bbb? Jan 14 16:31:02 probably the most common differential receivers you can find are rs422/rs485 receivers/transceivers, and they'll do fine for the job. Jan 14 16:31:21 gotcha. then i'll have to somehow get it to single ended correcT? Jan 14 16:31:37 they have single-ended output Jan 14 16:31:41 that's their whole purpose Jan 14 16:32:12 gotcha. i'll look this afternoon for a breakout, if i can't find one then looks like it's time to get the soldering iron back out. never done much with steppers before. learning is fun Jan 14 16:32:18 since you want to interface two encoders, each with two differential signals, you need either a quad receiver, or two dual receivers, or four single receivers Jan 14 16:32:28 gotta jet to a meeting, but i'll be back in a bit Jan 14 16:32:30 but quad receivers actually seem to be easier to find than dual or single for some reason Jan 14 16:32:36 ty for the help if you're not here when i'm back :) Jan 14 16:52:18 wg: rs422/rs485 breakouts seem to be limited to single transceivers and hella expensive, especially if you'd need four of them... if you really want to avoid sticking a quad receiver IC into a breadboard I guess you could also just ignore the ~a/~b signals and run the a/b signals through a 5v to 3.3v level shifter, there should definitely be breakouts for that Jan 14 17:06:25 I have a beagleboard black and a TI DLPDLCR2000EVM Projector Cape. Is it possible to use the HDMI and the Projector at the same time? Jan 14 17:07:06 well no but yes but no Jan 14 17:08:02 technically they conflict, though in principle they could be driven at the same time with the same video signal, but it would require being able to use video timings that make both of them happy Jan 14 17:08:44 I was hoping to use HDMI to display the OS and the projector to display a movie. Jan 14 17:09:02 they can definitely not be used independently Jan 14 17:09:17 ok Jan 14 17:09:27 basically the BBB's HDMI port is like a HDMI cape plugged into the base beaglebone Jan 14 17:09:29 Is there a beagleboard that would allow this? Jan 14 17:10:56 if the projector cape is compatible with the BBAI then it would allow it... that would require some careful examination though, not to mention that pinmux setup in general is still a big headache on the bbx15 and bbai, it's not plug-and-play yet like the BBB Jan 14 17:11:40 ok thanks for your help Jan 14 17:16:44 one downside is that the BBAI can only use 16-bit color for the video output on the P8 expansion header Jan 14 17:37:13 zmatt gotcha. I have 2 encoders total, so we will see what the best option is. I can probably layout a quick board on eagle and have proto boards here next week Jan 14 17:43:26 wg: if you end up not using differential receivers, try to avoid running the encoder wires parallel to the stepper motor wires, keep them apart Jan 14 17:43:41 to avoid coupling Jan 14 18:26:09 zmatt : will do Jan 14 18:26:17 ty for help, headed to lab now to check a few things Jan 14 18:50:51 sriramdhivakar[m: still looking for an X15 LCD? Jan 14 18:51:16 sriramdhivakar[m: I'd suggest the AM5728 EVM kit that comes with an LCD and mPCI interface. The display never went for sale on its own. Jan 14 19:00:09 zmatt so if i use 2 encoder inputs, does that effect my ability to use a pwm output? not sure if the counters are internally connected or not Jan 14 19:02:52 doesn't look like it according to the pinout, just wanted to make sure Jan 15 02:30:54 I read the New Year Resolution and things sound like people may make time for a couple of Open Source tutorials. Neat! Jan 15 02:31:50 I feel like I am jumping in b/c i want to learn but I am sure other people will find the resolution helpful too. Jan 15 02:33:31 I try to make tutorials, w/ the recommendation to reply if read, for people interested in what the boards can do. Jan 15 02:33:32 But... Jan 15 02:34:26 W/ all those tutorials from github, hackster.io, and hackaday.com, it will be hard for one person like me to keep up. Jan 15 02:34:34 But...I shall try more once i learn more. **** ENDING LOGGING AT Wed Jan 15 02:59:57 2020