| Electronics > Projects, Designs, and Technical Stuff |
| EMF pickup from amplifier in I2C line causing glitches. (Now with scope trace!) |
| << < (31/31) |
| janoc:
--- Quote from: Starlord on July 15, 2016, 04:30:02 am ---[edit] Eh, you know what, I'm done with letting you waste my time. --- End quote --- :palm: Good luck, you will need it. |
| andyturk:
--- Quote from: Starlord on July 14, 2016, 01:44:58 pm ---I don't have a degree in electrical engineering. I'm all self-taught. Nobody would hire me. And my software engineering skills are for the most part 20 years out of date. Do you know anyone who's looking to hire a C++ programmer who is well versed in Arduino? --- End quote --- Hey Starlord, we have a lot in common. I'm self taught too (as far as EE is concerned), with professional software skills from two decades ago (more like three, if I'm being honest). But I've never touched an Arduino, so you're ahead of me there. Even so, I've talked my way onto some fascinating projects in the past few years, and contributed firmware to two shipping consumer devices that you can buy today. I bought my first DMM in 2013, so if I can do it, you can too. You've gotten into a bad vibe here with the EEVBlog brain trust, but hopefully that's temporary. There are some really heavy-hitters here, who know their craft and are willing to help newbies like you and me. So, step a way from the keyboard for a while, chill out, get some exercise, whatever it takes, and then come back to ask good questions. These people *love* good questions, and they will help. |
| tggzzz:
--- Quote from: andyturk on July 15, 2016, 04:31:46 pm ---These people *love* good questions, and they will help. --- End quote --- ... and they do it because they enjoy helping people. |
| SteveyG:
--- Quote from: janoc on July 14, 2016, 07:26:10 pm --- --- Quote from: Starlord on July 14, 2016, 04:32:34 pm --- --- Quote ---Or at least recognize that you are way out of your skill level and get help early. --- End quote --- You think I just jumped into this without doing any research? One of the first things I googled was whether or not I2C could be made to work over long distances. The consensus was yes, it can. I then did the math, and according to the spec, I was good to go. http://electronics.stackexchange.com/questions/106265/maximum-i2c-bus-length --- End quote --- That is not what I meant. One of the key things to being a good engineer is to recognize own limitations and ask someone more skilled in the particular domain for help instead of carrying on and digging yourself into a hole, either because of lack of finances or too large ego (or both). By that I mean an actual engineer actually looking over/helping you design your product, not you cherry-picking irrelevant bits and pieces online. That StackExchange question doesn't consider neither the several feet of cable you are using nor the output of the power amp running parallel to your signal wires. Ever heard of crosstalk? Why did you even consider that it is somehow relevant to your problem? Moreover, none of the answers really apply to your case - guy running serial connection over many meters but using UART not I2C, another one using USB, etc. The only somewhat relevant info on that page is that last guy pointing out the P82B96 line driver - but you didn't choose to use that anyway, so ... If anything, you pointing to that link only shows you don't really understand what you are doing. Electronics isn't software engineering where you can often "wing it" and it still works, only perhaps a bit slower or less memory efficient. Physics doesn't give a damn whether you are trying to feed a family, doing it as a hobby or for profit. Either you do things properly and it will work or you don't and it will not. Flailing hands in the air and whining about people being mean to you won't change anything on that. --- Quote ---Can I guarantee that if someone is standing next to a CB radio that is transmitting that it won't glitch? No. I could not even guarantee that if I added a shielded cable and buffered the communications. I have absolutely no way to test it under every possible form of interference it might encounter. If it doesn't work in those instances though, so what? Why hold my device to a higher standard than my WiFi router designed by a company with hundreds of millions of dollars in he bank and dozens of highly trained engineers at their disposal, which stops working when the microwave is on? If there's interference, move away from the source. No big deal. --- End quote --- You should stop obsessing about CB radios, those are irrelevant to the problem. There are many other devices that rely on radio communication that you can be easily interfering with. Radio isn't used only by truckers, you know. When your neighbor stops being able to open his garage door because the receiver of his garage door opener will be saturated with the noise from your amplifier, he won't be happy. The same for grandma's hearing aid picking up the noise. Or a house alarm getting triggered few houses down the street. Your wifi router is FCC certified and has to accept interference, even if it means it stops working - 2.4GHz is the same frequency band that also microwaves use. That is the nature of that frequency band - shared use. Most frequency bands are not like that and things that are not certified as transmitters (and licensed) are not allowed to radiate anyway, whether intentionally or not. Your device has to be scrutinized more carefully than that cheap router, because it is not supposed to emit any RF to begin with. And it also pushes a lot more power than the 1W or so your router does, so the potential for shenanigans is much higher. BTW, rather than complaining about your router you should ditch your cheap microwave that is obviously leaking RF due to poor or damaged shielding (likely the door seal). You could have a much more serious issue than just not working wifi with that - it could be even a health hazard. --- Quote ---Sitting on my bench, the product worked fine. If there were any glitches, they were occasional, and barely noticeable, since they would only last for 1/60th of a second in between LED updates. --- End quote --- :palm: So the occasional glitches even on the bench in a controlled and pretty much ideal situation didn't actually make you wonder that something could be off with your design? If it was glitching on the bench already, in the real world it would not work at all - as you have discovered. You cannot engineer things to barely work on the bench hoping it will be good enough. But I guess you have learned that now. There is a concept of design margin that covers this. Dave uses the "belt and braces" term for it too. --- End quote --- Starlord, please absorb what janoc has to say. The replies are factual and will help you. It would be worth looking at a few online resources about EMC - specifically radiated and conducted immunity and emissions. There's plenty of good stuff out there, but you'll see a lot of your 'counter arguments' are not arguments at all. Rather than arguing, take a step back and read the posts without the mindset of feeling attacked - no one is actually attacking you, they're trying to help and warning you of the issues you will face or are facing. |
| 84750Erik:
Somehow I stumbled on this thread, and after reading the whole thing I am wondering how our StarLord might have ended up. |
| Navigation |
| Message Index |
| Previous page |