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According to your scope trace, what you're seeing there is only about 0.3V at its peak. That's not a logic-level signal. It might be some sort of crosstalk or induction from somewhere else in the circuit, or leakage from something that got fried, but it probably isn't something the microcontroller is supposed to be doing. If you're seeing the same signal on every pin I'd say that makes it even more likely to be an error. The frequency is reporting as about 4 Hz. I can't think of many things that the chip would be doing on startup that would have that frequency. Attempting to blink a status LED? Maybe it's the result of a repeated reset attempt from the computer that keeps failing?
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Jul 15, 2021 05:52
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PRADA SLUT posted:Trying to debug, I hook a scope up to the pins, and I get a qualitatively similar output on nearly all the I/Os, and a few pins like the ground pin: If you're seeing that signal at multiple pins including ground, as far as those pins are concerned they're driving 0V. And there's either a lot of resistance or a lot of current between wherever your scope is grounded and the IC's ground pin. Stack Machine fucked around with this message at 06:26 on Jul 15, 2021 |
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Jul 15, 2021 06:24
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Marsupial Ape posted:I'm starting to get a little bit of a headache sourcing 18650 batteries. Should I just go with the flat, rectangular 3.7 volt Li-ion batteries? Can you run those in series with a step down board to get 5 amps? I was reading up on those recently, too. I found this really helpful page, though it is aimed at video game hardware: https://bitbuilt.net/forums/index.php?threads/portables-and-batteries-a-guide-and-explanation.2228/ Also new to this, so I'm not confident on what "step down board" means, but if you mean buck converter or LDO by itself I don't think that is sufficient. (If I'm wrong about what you meant, my bad, just ignore this then): Bitbuilt posted:When implementing lithium batteries you must ALWAYS use a protection board. There are basic protection boards and some that are more robust. These are usually listed with a variety of names which adds to the confusion. They can be called some of the following PCB, PCM, BMS, and/or CMB. Basically, one pack ("cell") is much, much simpler than a multi-cell setup, but for any lithium ion or lithium polymer battery even if you have only 1 cell, you need charging circuitry for the following reasons: 1) if you plug it into a charger, the circuitry must know when to disconnect it from the power source. Overcharging a lithium cell can cause it to puff up and explode 2) if you are on battery power, you must disconnect the battery or start charging it before it drops below a specific voltage. Overdischarging a lithium cell will break down the internal chemical composition and that will greatly reduce it's overall lifespan 3) if you have a multi-cell setup, you must use a balancing circuit because each battery will not have exactly the same voltage at all times due to the physical impurities in each specific individual pack. If the cells are not constantly balanced, you will eventually have scenario 1) happen to some cells and 2) happen to the others Also, the soft, flat cells are much more delicate than the 18650's and I guess are more prone to puffing up and exploding: Bitbuilt posted:As for the Li-Po cells, there's more variety in the form factor so there isn't a recommended physical size. One thing to note about Li-Po flat pack cells is that they are very fragile. Excessive heat from improper charging and discharging can cause these cells to swell. Once these cells swell they are a ticking time bomb! The form factor also contributes to the fragility of this type of cell. They are soft and malleable when compared to the hard shell of an 18650 cell. This makes Li-Po cells prone to punctures from surrounding through-hole mounted components in a portable. If you puncture a cell it will go up in an inferno. I think this stuff I wrote is what ante was referring to. vvv ante posted:Yeah, they're essentially identical to 18650s. I'm assuming you're familiar with balancing and the risks associated with not doing that Cory Parsnipson fucked around with this message at 06:38 on Jul 15, 2021 |
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Jul 15, 2021 06:33
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ante posted:I don't know who needs to hear this, but thermal cameras are also getting pretty cheap now. My $300 handheld one is among my most-used piece of test gear, and I point it at every board I bring up for the first time. I actually am in the market for one of these. Options?
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Jul 15, 2021 07:03
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My general plan is to use two 18650s in a holder paired with one of These. That's for the FM radio I plan on making. The actual bluetooth board I am using for another project is actually designed to be powered by a flat li-po cell with a built in PCB.
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Jul 15, 2021 07:26
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ante posted:I don't know who needs to hear this, but thermal cameras are also getting pretty cheap now. My $300 handheld one is among my most-used piece of test gear, and I point it at every board I bring up for the first time.
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Jul 15, 2021 12:49
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Dominoes posted:Saved me on my battery issue by finding the 2 components continuously drawing mA-order current on a battery-powered device. We (well, the techs) used them at a refrigeration place I used to work at. They are amazing for finding things like poor connections on a massive control board
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Jul 15, 2021 13:23
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PRADA SLUT posted:Also, I hooked up a USB meter to the cable and it reads 5V 1A when it's hooked to the computer (and enabled--0A when not enabled), but when I hook it to a power-only USB outlet the amperage fluctuates between ~0.3A to 0.8A. Any decent dev board should have voltage regulators capable of providing whatever that peak current it. But maybe your USB voltage is drooping?
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Jul 15, 2021 13:39
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PRADA SLUT posted:I considered that, but why would the pins output a signal then? I assume I’d get either garbage or nothing. ante posted:ICs are complicated beasts. It's entirely possible that an internal diode blew, shorting power to ground, but with juuuuust enough resistance that the LDO can mostly handle it, and the ESP32 doesn't melt immediately This has been my experience with 3V3 boards. 5V gets in the wrong spot and the internal protection diode shorts closed. There's not enough trace width to let the thing draw enough current to pop the die off the package, but the chip gets very hot. I have a couple of ATMEGA chips and at least one Raspberry Pi that do this. For the ATMEGAs, I was able to voltage-probe around with my scope and find the pin that was sinking current and lift it from its pad to solve the issue. That whole peripheral ended up being burned out, so the other 7 pins on the port became output-only.
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Jul 15, 2021 15:12
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PRADA SLUT posted:I actually am in the market for one of these. Options? Bizarre that they came up, I asked for one for my birthday this year cuz I'm tired of burning my finger trying to find short circuits  I looked around a bunch before deciding, here's my criteria: I want a proper FLIR and not a knockoff. I don't know if the knockoffs are any good, but they're all still pretty expensive so if you're going to be spending a few hundred bucks you might as well just get a proper FLIR. I want one with at least the 160x120 IR sensor in it. I've seen the lower-res 80x60 ones demo'd and I just don't think there's enough resolution there for me, even with the weird image enhancement thing the FLIR's do. Might be fine for your use cases though. I want an all in one thing, not one of the ones that hooks up to a smartphone and uses an app. I like the gun-type design but that's just personal preference Going by these, I decided on the FLIR TG267, which is about as good as they get before the prices go absolutely bonkers. It's still like $500, but the next step up is over $1000, so yeah. (If you're wondering, I asked my family and friends to pool and get it as my one present this year, I'm not gonna ask for a $500 gift from one person lol) Anyway if you don't care about it being all-in-one and are fine with hooking it up to a phone, the latest FLIR One Pro's have the exact same 160x120 image sensor in them and cost a solid $100 less, and if you're okay with going down to lower resolution the One Pro LT gets you all the way down to $180 on Amazon right now: https://www.amazon.com/FLIR-ONE-Thermal-Imaging-Camera/dp/B07DMK1ZKP/
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Jul 15, 2021 15:26
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The one I bought is a UNI-T UTi165A. They also have a bunch of similar models, I'm not sure what the differences are. I like a lot of UNI-T gear, it's a solid Chinese brand. And this one has a ridiculous battery life, feels solid, and works really really well. Non-FLIR thermal cameras aren't "knock-offs", they're just a different brand. They're not trying to be FLIR.
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Jul 15, 2021 15:54
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ante posted:The one I bought is a UNI-T UTi165A. They also have a bunch of similar models, I'm not sure what the differences are. I get what he means though I think. When I was looking at doing a DIY one, the only sensors I could find on mouser were way shittier (well, much lower res I didn't check every stat) than what FLIR uses. When I looked into it sounds like the only way to get the FLIR sensors was to steal them out of the FLIR devices. IIRC the highest res I could find on Mouser ~1 year ago was like 64x64, maybe even 64x32
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Jul 15, 2021 16:03
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ante posted:The one I bought is a UNI-T UTi165A. They also have a bunch of similar models, I'm not sure what the differences are. By knock-offs I meant the ones that are actual knock-offs, not like UNI-T or this one I saw from Klein Tools that looks fine too: https://www.amazon.com/Klein-Tools-TI250-Rechargeable-Temperature/dp/B089QW8R9S/ Like if you just put "thermal camera" into amazon a bunch of things like this come up along with FLIR and other "real" brands:   Thermal cameras are slowly becoming one of those products where amazon will have 50 "brands" called Fweer or Eqgoo or whatever in between the actually good ones.
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Jul 15, 2021 16:04
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The main reason I wanted a FLIR though (besides having used it in person and knowing it works) is because it does that visual-light-camera-edge-detection-overlay thing, idk if other cameras can do that but I already know the FLIR can do it and do it real well, so eh. Also to their credit HIKMICRO actually have a website so maybe it's just a brand I haven't heard of. I really like this bit on their About Us page too: https://www.hikmicrotech.com/en/about  256 Masters and PhD's!
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Jul 15, 2021 16:13
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babyeatingpsychopath posted:This has been my experience with 3V3 boards. 5V gets in the wrong spot and the internal protection diode shorts closed. There's not enough trace width to let the thing draw enough current to pop the die off the package, but the chip gets very hot. I have a couple of ATMEGA chips and at least one Raspberry Pi that do this. For the ATMEGAs, I was able to voltage-probe around with my scope and find the pin that was sinking current and lift it from its pad to solve the issue. That whole peripheral ended up being burned out, so the other 7 pins on the port became output-only. Let's assume I can hit any trace on the board. How would I apply a correct voltage to the MCU, while still allowing for uploading a program over usb from the computer, without drawing USB power? I can see how I do the former, but not both at the same time. Would I need to shunt USB +V but keep the data pins? e: I don't have a JTAG connector for USB > Serial off-hand to try and hit the serial traces directly, bypassing the USB stage. PRADA SLUT fucked around with this message at 16:46 on Jul 15, 2021 |
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Jul 15, 2021 16:36
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I think I mentioned way back in this thread that I had been using a Seek Thermal Compact and was very happy with it. Now my job has its own Fluke thermal camera (the Ti25 I think), so I don't use the Seek very often, but there's not much I can do with the Fluke that I can't do with the Seek. Main benefit on the Fluke is the focusing wheel, but I can't say that's worth the price difference. Main thing I wish the Fluke had is a way to trigger it from an external signal. AFAIK even their new models lack such a feature. Best option is to rig up an Arduino to drive a solenoid to pull the trigger. Just floored me that I had to rig up some rube goldberg poo poo on a fluke instrument. ANIME AKBAR fucked around with this message at 16:59 on Jul 15, 2021 |
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Jul 15, 2021 16:51
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Shame Boy posted:The main reason I wanted a FLIR though (besides having used it in person and knowing it works) is because it does that visual-light-camera-edge-detection-overlay thing, idk if other cameras can do that but I already know the FLIR can do it and do it real well, so eh. I've always had a bit of a problem with that visual light overlay thing because the parallax offset between the IR camera and the visual light camera works at longer distances but becomes really pronounced when you're trying to look at a PCB up close to see what's hot. The ones I use have an image distance setting that partly corrects for it but still doesn't work 100%. I've also had bad luck with FLIR cameras that have a micro USB port - they just seem to disconnect constantly and at the worst possible time. Still a useful tool to have though.
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Jul 16, 2021 03:42
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Since I am hunting around for them, where is the best place to get 18650 batteries?
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Jul 16, 2021 03:44
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I've seen piles of old drill batteries at junkyards If you're okay with a slightly different cylindrical form factor, you can peel apart a Tesla Do this so they can't get away: 
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Jul 16, 2021 03:46
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The battery pack might even have as many as you're looking for. Make sure to remove the electrical tape and paper clips.
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Jul 16, 2021 03:58
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I mean like an online retailer, guys.
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Jul 16, 2021 04:30
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Sparkfun, surprisingly enough, has em pretty cheap. They're the older ones without the "b" suffix so they have 2600 mAh capacity instead of the nominal 3400. Also just to reiterate, a li-po charging circuit should be fine, but if you decide to take that and wire more than 1 cell in series/parallel, you need to make sure it has balancing features. e. oops, the sparkfun batteries are from a Chinese manufacturer and not like, Samsung, or anything. So the specs won't be as good. If Sparkfun is selling it, I think it should still be reliable. Cory Parsnipson fucked around with this message at 04:35 on Jul 16, 2021 |
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Jul 16, 2021 04:33
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Do The Three Laws apply to Tesla?
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Jul 16, 2021 04:44
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Now you done it Does it prioritise the passenger over a cat running across the road? The passenger over a pedestrian? The passenger over two pedestrians?
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Jul 16, 2021 04:45
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Do they really have human-pullable levers at railway intersections? What about robot-pulled levers?
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Jul 16, 2021 05:02
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Cory Parsnipson posted:Sparkfun, surprisingly enough, has em pretty cheap. They're the older ones without the "b" suffix so they have 2600 mAh capacity instead of the nominal 3400. Thank you. I just need a 4 or so for putting together prototypes and general "did I do this right?" stuff. When I actually do a real-deal project that involves making something that's permanent, I'll get the good Samsung batteries.
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Jul 16, 2021 05:31
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I bought piles of old laptop packs off eBay and shucked 'em so I've been working through that stash, but Orbtronic (https://orbtronic.com) is the best online retailer I know of for batteries. That Sparkfun price ain't bad though
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Jul 16, 2021 05:40
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ante posted:I've seen piles of old drill batteries at junkyards Remember that a good hunter uses every part of the prey
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Jul 16, 2021 05:56
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Forseti posted:I bought piles of old laptop packs off eBay and shucked 'em so I've been working through that stash, but Orbtronic (https://orbtronic.com) is the best online retailer I know of for batteries. That Sparkfun price ain't bad though Ooh that's good stuff. Do you do anything to gauge the condition of batteries you get off ebay? Or just shove them in and toss them at the first sign of puffage/lifecycle failure?
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Jul 16, 2021 05:59
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Just check the voltage. Between 2.8 and 4.2v, and they should be fine Edit: only use banks with like batteries. Don't mix and match
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Jul 16, 2021 06:02
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Cory Parsnipson posted:Ooh that's good stuff. Do you do anything to gauge the condition of batteries you get off ebay? Or just shove them in and toss them at the first sign of puffage/lifecycle failure? It's super tedious, but yeah, you can use a battery charger to discharge and charge them and measure the capacity of each one. It's important to bin the cells to match up like conditioned ones if you're making battery packs. Inspect for damage and don't be afraid to toss them or at least don't use them in another pack. I'm wanting to build an additional battery pack for an eBike but haven't actually gotten around to it yet... I did measure all my cells though and stuck it into a sqlite db. In the end I bought 154 cells and had 10 discarded and a significant portion near end of life, but it was waaaaay cheap per cell vs new, averaged $1.09 per cell.  I'm using an Opus BT C3100 to charge. Not too cheap at $52, but it's worked great for me so far: https://www.amazon.com/gp/product/B01852TBOU You can get a bunch of chargers to make the testing go faster if you're really building some massive packs, but I just did it the tedious way over some days. You'll also want to refurbish with fresh wraps and insulators, another $18 for more than enough to cover the whole pile. https://www.amazon.com/dp/B07H6TF58L https://www.amazon.com/dp/B072LQQMDQ It doesn't look bad when finished!  Before and after, although the afters were from a different cell than this particular one.
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Jul 16, 2021 06:33
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drat, now you've got me chomping at the bit to build a nice portable battery or two for my ham radio park adventures. I only need like 100Wh or so, but having a couple or three units might be great.
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Jul 16, 2021 07:11
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Jonny 290 posted:drat, now you've got me chomping at the bit to build a nice portable battery or two for my ham radio park adventures. I only need like 100Wh or so, but having a couple or three units might be great. Well if you do please post the results.
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Jul 16, 2021 13:14
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Jonny 290 posted:drat, now you've got me chomping at the bit to build a nice portable battery or two for my ham radio park adventures. I only need like 100Wh or so, but having a couple or three units might be great. You should! 100Wh is totally doable. Not sure you can do one for wildly cheaper than buying, but probably a bit cheaper and then you'll have paid for the costs of equipment for future projects. If you assume you'll average 2200mAh/cell (which seems reasonable IIRC, I'll have to check the numbers I got with mine) that's ~13 cells. Most of the packs I took apart were 8 cells, some were 6, and I think some may have had 10. In addition to the above, to make a pack you'll need: Nickel strip to connect the cells: https://www.amazon.com/dp/B08QCL4L2Q Spacers to keep batteries secure and separated: https://www.amazon.com/dp/B07BN7K8CX Maybe some more insulator paper in sheets to throw over big regions. Probably lots of kapton tape to use liberally if you don't have any one hand. You'll need a spot welder to weld the nickel strips onto the cells. I haven't done all my research on these, but probably worth it to pay a little more and get a good one rather than deal with frustration of a marginal one making weak connections
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Jul 16, 2021 14:15
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Marsupial Ape posted:I mean like an online retailer, guys. I was going to post that you can just search for specific known brands on ebay (like Panasonic NCR18650B or Samsung 25R) and get decent results, but then I got to thinking that it's ebay so you really have no guarantee they're genuine or not... I mean I've done it plenty and they seem to be well-constructed and have the full stated capacity but yeah... Anyway sparkfun sounds perfectly reliable, didn't actually know they sold them, neat.
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Jul 16, 2021 15:18
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We're doing some audio stuff at work and one issue we always have to contend with is high-amplitude low-frequency impulses saturating the ADC, which arise from things like physical tapping of the microphone. I don't want to reinvent the wheel here; I feel like this is something that the audio world has surely dealt with. I'm vaguely aware of things like limiting circuits and soft clippers, but looking this stuff up its largely presented in the context of intentional distortion. Any ideas or some keywords here would be most helpful!
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Jul 16, 2021 16:00
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oops, disregard.
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Jul 16, 2021 16:01
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Design in a big label that says "Don't tap the mic"
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Jul 16, 2021 16:26
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Set up snipers to shoot anyone about to tap the mic.
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Jul 16, 2021 16:34
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I'm reading about TOSLINK / S/PDIF since I decided to use the optical connectors for a (not-audio-related) data link in something, and I found this site with these delightful 20+ year old ascii-art schematics: https://www.epanorama.net/documents/audio/spdif.html   I really like the transformer in particular.
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Jul 16, 2021 16:34
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