TotalLossBrain posted:The hugest problem in engineering is actually preventing engineers from experting outside their narrow field.  Hi all I am looking to get into a few DIY projects this summer, first and most specifically one regarding a chicken coop I just built https://forums.somethingawful.com/showthread.php?threadid=3468084&pagenumber=202#post504532354 First I need to learn how to set up a Raspberry Pi based sensor setup that also controls a servo or two and maybe another circuit or two as well. I had been thinking of doing something silly like building my own MPPT controller for a solar system for this and going down that rabbit hole, and also just looking into things I'd need to do in general I realize I need to get some more tools and also have some big knowledge gaps regarding materials. Tool-wise I have a decent multimeter and stuff relevant to larger (home power) electronics and just a little experience with that and the Black and Decker electrical code manual for home wiring. Still trying to figure out what I don't even know about yet but have identified a couple things that I could use advice / suggestions on: 1. I have zero soldering apparatus. What is a good set of tools, iron, flux, materials, 'must-have' / 'really nice to have' accessories for soldering small work like this? Huge bonus points if I can order online and ship to me. People mention "get a good soldering iron", I have no way to know what's good and what's crap. I'm not gonna be doing this full time so I don't need the tip top model but wouldn't mind something better than crap. 2. Any guidance on a grab bag of wiring and connectors for this project and willing to buy something more expansive here to use for other things down the line. Online ordering again preferable. One thing I have no knowledge of is how to choose what types and sizes of wires for each application, nor do I know why you'd choose specific types of connectors vs others. Hadn't come across a good intro source for that kind of thing yet.
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May 2, 2020 13:14
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As recommended to me earlier in this thread: Hakko FX-888D Hakko chisel tips MG desoldering braid, if you're doing SMT. Anyone have flux or solder recs? Buy a fan so you don't inhale flux (The smoke); it can cause respiratory problems. A "helping-hands" setup with tweezers is also useful, but I don't have recs. I bought a Dr. Octopus thing on Amazon, and can't recommend it due to how positioning the hands is likely to unscrew them. Tweezers and a magnifying device are also useful if you're doing SMT. It's become evident that it's important to get good tips. Anecdotally, I've noticed a big improvement in wetting, resistance to oxidation, and heat transfer with Hakko tips. (Although the latter could be due to a switch from conical to chisel) There's also a good deal of leaded vs nonleaded solder chat a few pages back. TLDR is leaded solder works better, and you can assess how much lead exposure you're comfortable with. If you go the leaded route, wash your hands thoroughly after each exposure to solder or your products, and make sure you have a separate workspace from your normal activities. Also note that the flux is toxic. Let me know if you have any pi-specific questions; I've been doing a lot of that lately using a CM3, and have been writing the code in a way that abstracts onto other microcontrollers using a HAL. (eg I was able to use the same RTC and code for it on both the Pi and a STM32 board.) Overall, you can treat it like a computer with interfaces, or a microcontroller that has some nice features, like a filesystem, display support, and heap. Dominoes fucked around with this message at 16:29 on May 2, 2020 |
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May 2, 2020 16:13
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Here's another "do you know a thing to do X" request. I like using lots of pin headers on my boards for debugging. Like usually 4-8 dual row headers, totalling 50-100 pins. Usually I use 0.1" pitch so I can easily hook up my 16 channel logic probe. But these headers take up a ton of board space. I'd like to use a smaller pitch header (like 0.05") while still being able to use the logic probe:  One simple idea is to use an adaptor board like this:  But then I'll need to be very careful about height/spacing restrictions on nearby components, including other headers. Not very convenient. Ideally I'd like something flexible, like a cable. Maybe like traditional jumper wires:  But with 0.05" pitch on the female side. I could just stick a short one into each logic channel and use it with a 0.05 header. I can't find such a thing though. In fact, I can't find any jumper wires for 0.05" pitch, period. The closest thing I can find off the shelf are IDC ribbon cable adaptors that come with MCU programmers (like Atmel's JTAG ICE3). But they're highly specialized, and I can't find one available that really fits my needs. Any ideas? ANIME AKBAR fucked around with this message at 18:43 on May 2, 2020 |
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May 2, 2020 18:32
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Hmmm maybe pogo-pin type connectors like this? https://www.tag-connect.com/ You could make something that adapts it to your logic probe cable and then on the PCB side it's pretty much just a footprint.
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May 2, 2020 18:40
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Dominoes posted:As recommended to me earlier in this thread: Thank you! I am not planning to do much if any SMT yet but that may change as I learn more about what might work best for my project. I went through your posts and saw a good bit of the back and forth regarding tips, solder etc. I'll probably take you up on the Pi stuff at some point but right now I am starting from a much further back beginner point and have lots of stuff out there to read and learn before I get to specific questions I think (hope). Thank you.
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May 2, 2020 19:06
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That Works posted:1. I have zero soldering apparatus. What is a good set of tools, iron, flux, materials, 'must-have' / 'really nice to have' accessories for soldering small work like this? Huge bonus points if I can order online and ship to me. People mention "get a good soldering iron", I have no way to know what's good and what's crap. I'm not gonna be doing this full time so I don't need the tip top model but wouldn't mind something better than crap. Seconding the recs you already got for this, but wanted to add: the best way to learn soldering imo is to just get a cheap kit that's vaguely interesting to you and put it together in an afternoon. That way you can mess up on something inexpensive using parts that don't matter rather than your final project, and if you do it right you get to keep a little doodad too. That Works posted:2. Any guidance on a grab bag of wiring and connectors for this project and willing to buy something more expansive here to use for other things down the line. Online ordering again preferable. Ehh grab bags are pretty universally a crap shoot, you can buy assortments and stuff on ebay or amazon but they're generally low quality. One thing not mentioned though is that you'll probably want a breadboard, they're priceless for prototyping. You can get them in packs with a bunch of other random useful stuff, like this: https://www.amazon.com/Makeronics-Tie-Points-Electronics-Potentiometer-Prototyping/dp/B07WL87KHB/ That one comes with a bunch of jumper wires, a breadboard USB power supply, random resistors, LED's, capacitors, and other crap you can fiddle with that's useful to have around. Probably not great for any sort of permanent circuit, but fantastic for just trying ideas out without having to make up a circuit board or solder things together. e: Wait that breadboard power supply isn't USB powered, it's powered by an external 6-9V barrel plug wall wart, sold separately. The USB is just there so you can also connect up your arduino or whatever and power it all from the same thing. Shame Boy fucked around with this message at 21:56 on May 2, 2020 |
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May 2, 2020 21:54
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Just figured out why the Pi doesn't include a RTC... The RTC chip alone is bigger than another part on my board other than the DIMM slot, and the battery takes up 6 times that. Maybe I could put it on the back, although couldn't get that done by the board maker.
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May 2, 2020 22:10
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Dominoes posted:Just figured out why the Pi doesn't include a RTC... The RTC chip alone is bigger than another part on my board other than the DIMM slot, and the battery takes up 6 times that. Maybe I could put it on the back, although couldn't get that done by the board maker. Bigger than the USB slot? I thought there were lots of QFN-16 or whatever RTCs these days
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May 2, 2020 22:19
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TotalLossBrain posted:The hugest problem in engineering is actually preventing engineers from experting outside their narrow field.
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May 2, 2020 22:21
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Dominoes posted:Just figured out why the Pi doesn't include a RTC... The RTC chip alone is bigger than another part on my board other than the DIMM slot, and the battery takes up 6 times that. Maybe I could put it on the back, although couldn't get that done by the board maker. I have an RTC on my current board that's a pretty standard SOIC-8 size, along with a tiny crystal to go with it. What the heck RTC chip are you using? As for the battery, nothing much you can do about that other than maybe just use a connector and wire a battery holder off the board. If it's not going to be powered down for long periods of time you could also just use a big ol' capacitor, should be able to keep it running for ~10 minutes. If this thing is going to be network connected or USB connected or something, you can just set the time using that too and not have to worry about whether or not the RTC loses time.
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May 2, 2020 22:22
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I stand corrected - the USB slot's bigger, as are the 10-pin headers. It's a SOIC-16.
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May 2, 2020 22:22
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Dominoes posted:I stand corrected - the USB slot's bigger, as are the 10-pin headers. What the hell RTC is that, that's enormous 
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May 2, 2020 22:23
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Maybe I could use a smaller one? I just picked the one that's on the breakout boards: DS3231. Arbitrarily picked a popular one, and have the breakout board working. It has a Rust HAL driver, which makes things easy.
Dominoes fucked around with this message at 22:27 on May 2, 2020 |
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May 2, 2020 22:24
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That Works posted:
grab a ts100 and go hog wild, 63/37 is good, Sn100C is lead free, get it flux cored. Eutectic alloys reduce the chance of cold soldering/cracks. For small SMT Pace ADS200 + tweezers can't be beat but it's real expensive. Otherwise use a small tip, some kapton tape. I like amtech flux for that. Make sure you have the area well ventilated and use a mask, the flux fumes are nasty even if you get Halide-free/Zero halide fluxes.
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May 2, 2020 22:25
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Dominoes posted:Maybe I could use a smaller one? I just picked the one that's on the breakout boards: DS3231. Arbitrarily picked a popular one, and have the breakout board working. It has a Rust HAL driver, which makes things easy. Looking at the DS3231's datasheet, the reason why it's so big is because it has an integrated TCXO so you don't need an external crystal. That's... kind of excessive for your project I'd think. It'll be super duper accurate, but also enormous compared to just a small RTC + small crystal  I mean if it works and you can fit it, then there's not really any compelling reason not to use it, it's just, well, big.
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May 2, 2020 22:28
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There's a DS3231M avail in a smaller package, and some other ones that also have a HAL driver (ie woulud be easy to change). Maybe could do that. There's 4 main DS323x family ones that have diff feature sets that I don't think would matter. Even this one has things like a square wave and 32KHz thing which I don't need. (ie when I leave them not connected on the breakout, things still work!) Btw, having existing drivers is no joke of an advantage. I switched ADCs because I couldn't get the SPI one working, but the I2C one had a driver. Dominoes fucked around with this message at 22:35 on May 2, 2020 |
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May 2, 2020 22:30
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You could probably claw back a ton of board space by switching to much smaller headers, right? Like those things are chunguses by modern standards I would think.
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May 2, 2020 22:35
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Good idea. Using the KK 2.54. (Today I learned a new word) I may need need to increase board size anyway. Space isn't a huge issue, but I understand price scales considerably with board size. There are pockets of empty space too, and I think I can get away with putting parts under the Pi. Also, trying to get away with moving to an STM32 or something, but it looks like the GUI and a few other things are holding me to the safety and security of Linux.
Dominoes fucked around with this message at 22:43 on May 2, 2020 |
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May 2, 2020 22:41
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Dominoes posted:Good idea. Using the KK 2.54. (Today I learned a new word) I may need need to increase board size anyway. Space isn't a huge issue, but I understand price scales considerably with board size. There are pockets of empty space too, and I think I can get away with putting parts under the CM3. I wish I had pictures of some relatively recent smallish-run specialty industrial boards from my job to show you. Single-sided boards, boards that were like 150x300mm, the works. Boards designed in the 80s, through-holes everywhere. It all depends on what your market looks like and how sensitive they are to price and how many options they have in general I think.
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May 2, 2020 22:44
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Dominoes posted:Also, trying to get away with moving to an STM32 or something, but it looks like the GUI and a few other things are holding me to the safety and security of Linux. What are the requirements? If you're brave you can try something like Allwinner's f1c200s SoC. I actually just ordered 5 for ~$15 from China to try out myself. It's an old core (ARM v5) but it runs Linux and it has 64MB of RAM included in the SoC. I have the LicheePi Nano board from Seeed based on the f1c100s which is the same thing but with 32MB RAM. It's pretty fun to play with but you are way more on your own than you are with an RPi obviously. Like you'll want to be familiar with building U-Boot the boatloader, the Linux kernel, Buildroot for the system, and comfortable mucking about with device trees. But it's cheap and I'm having fun! Mainline support is pretty decent for the older Allwinner chips even though the company sucks at open source. The community does pretty well though. I guess if your goal is to make something you can sell you'd definitely want to stick to things you can buy from Mouser/DigiKey though. STM32 is fun, as I mentioned a few pages ago NuttX is a pretty nice almost Unix experience. Mainline Linux has support for some of the STM32s via ucLinux but I've never used that and don't know if it's less hassle than just using NuttX. PIC32MZ DA can run Linux but they're probably as expensive as the CM3 is anyway. Not too familiar with NXP's lineup but I'm pretty sure they make a bunch of parts that can run Linux too.
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May 2, 2020 23:03
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The current dependencies that are tied to having a normal computer (ie that can't be run with Rust's `no_std` embedded mode) are: - Gtk. This is the big one. Could possibly replace with lvgl. Would have to make Rust bindings, or get the WIP ones working. - Display drivers. They're probably out there, but will take research and/or tweaks. - HTTP requests / WIFI. I'm suspicious this could be replaced with a wifi-device-specific driver, since internet access and server interaction is common in embedded - [de]serialization from json: Could hand-write this, or try to get the broken `no_std` version working - Some standard library features that use the heap like Vec (Like a Python list), and RC, a smart pointer that allows interior mutability of data structures, like the ones holding config and peripherals. I think these can be fixed by using the STM's allocation model, but haven't tried. -Downloading an updated version of the program from the internet, then using a secondary loader program to choose the newest (working) version. I'm not sure if this would be easy, tough, or impossible. On Linux, it's easy. I think that's it; have tried to make as much as possible embedded compat already. Using generic functions with traits, `no-std` drivers tied to the peripherals, not Pi etc. Nice. Sounds like a stepping stone after getting buildroot working on the Pi vice Raspian. Although ditching Linux entirely is ultimately the goal... I like the idea of not having a bunch of background processes I don't need not running. Currently can't get buildroot to compile, but I suspect it's related to WSL. Dependency hell or something. Dominoes fucked around with this message at 23:44 on May 2, 2020 |
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May 2, 2020 23:33
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Re internet updating. I'm sick of seeing products that have software inconveniences that are never addressed. When rando internet person or goon says "Your UI sucks", or "It acts weird in this edge case", I want to be able to fix it, big or small.
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May 2, 2020 23:55
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Forseti posted:Hmmm maybe pogo-pin type connectors like this? https://www.tag-connect.com/
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May 3, 2020 00:38
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Forseti posted:What are the requirements? If you're brave you can try something like Allwinner's f1c200s SoC. I actually just ordered 5 for ~$15 from China to try out myself. It's an old core (ARM v5) but it runs Linux and it has 64MB of RAM included in the SoC. I have the LicheePi Nano board from Seeed based on the f1c100s which is the same thing but with 32MB RAM. It's pretty fun to play with but you are way more on your own than you are with an RPi obviously. Like you'll want to be familiar with building U-Boot the boatloader, the Linux kernel, Buildroot for the system, and comfortable mucking about with device trees. But it's cheap and I'm having fun! Mainline support is pretty decent for the older Allwinner chips even though the company sucks at open source. The community does pretty well though. I've been going through George Hilliard's Mastering Embedded Linux series to get the LicheePi going from scratch. Seems straightforward so far, but I haven't actually tried booting up yet. ANIME AKBAR posted:Here's another "do you know a thing to do X" request. Put a 40 or several 40-pin FFC headers on there. You'll have to spin an adapter board that breaks out a different FFC connector to 2.54mm headers or whatever you like, but that should only take half an hour
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May 3, 2020 01:08
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Nice, I came across his blog posts and they're really nice. I was already pretty far into it by that point though, my first exposure was the Bittboy PocketGo emulator thingy from China which uses the SoC. Most of the stuff is included in the mainline kernel at this point which is really nice. I had messed around with the NTC CHIP quite a bit at that point so I was already pretty familiar with Allwinner stuff and it's not too different. I plan to copy his circuit to layout a simple PCB when my chips get here though! Embedded Linux is a lot of fun, a great way to get into the guts of Linux in general since the system software is so bare bones. Buildroot is awesome and makes rolling your own system a cinch.
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May 3, 2020 01:40
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What’s a good starter connector standard that has a low barrier to entry, particularly irt tooling, and isn’t the usual 0.1” breadboard-friendly pin/socket header that lives on jumper wires and dev boards everywhere? Or should I just stick with those if I don’t much tooling outlay? Most of the previous ideal-pick recommendations in here i’ve seen in here previously have been extremely slick but they come with a “and a decent crimper is only $160” -type rider that makes it a non-starter for me, the guy who prolly isn’t gonna do this more than a couple times this year Ambrose Burnside fucked around with this message at 02:46 on May 3, 2020 |
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May 3, 2020 02:24
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The real mccoy versions of all of them are expensive AFAIK. I use "DuPont" a lot which is what you're talking about (they're actually called something different that I forget but the knockoffs say DuPont). Also knockoff JST-XH like this: https://www.amazon.com/GeeBat-460pcs-Connector-Housing-Adapter/dp/B01MCZE2HM The knockoff JST-PHR at 2.0mm spacing is nice sometimes as well. The crimper I use is this: https://www.amazon.com/gp/product/B078WNZ9FW it's cheap and does a great job but it's super tedious to do a bunch of connectors, not gonna lie. Edit: fixed 1st link
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May 3, 2020 02:38
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re: soldering iron chat. I bought a Pace ADS200 and it has been probably one of my best purchases to date. I regret nothing about it. It's perfect.
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May 3, 2020 02:49
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they are really nice and the cartridge tips last
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May 3, 2020 02:50
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Sweet, thanks. I already have a bunch of JST-xh connectors i salvaged from some old appliance PCBs i’ve been stripping for parts, was wondering what they were called. On a different note- anybody have a reference/resource irt standards for weatherproofing electronics? i built an esp32-based ultrasonic sump level tracker a while back, for use indoors in a sump that’s usually dry, but it never got used; now i have a friend who wants one to monitor his shallow well and send the readings to a base station in the house nearby, and i’m happy to turn the existing assembly into his expanded idea, but it’s just a pile of exposed circuits shoved in a paperboard “enclosure”. It needs to be waterproofed- part of it would be fastened to the underside of the well cap, which deals with constant moisture and cold temps in winter- and the enclosure will also need sealed gland/s for a cable pass-through, as it’ll need at least a solar panel and antenna outside the well fully exposed to the elements. I know “waterproof junction boxes” are a thing but beyond that I don’t really know anything about how to effectively weatherize sth like this. beyond, like, just potting the whole thing in epoxy or sth.
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May 3, 2020 02:51
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Ambrose Burnside posted:What’s a good starter connector standard that has a low barrier to entry, particularly irt tooling, and isn’t the usual 0.1” breadboard-friendly pin/socket header that lives on jumper wires and dev boards everywhere? Or should I just stick with those if I don’t much tooling outlay? Got the RTC to fit in a place that was just traces, Top left. Put the battery on the back. 
Dominoes fucked around with this message at 03:04 on May 3, 2020 |
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May 3, 2020 02:57
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Well I ordered a TP-Link HS-100 smart plug for $10 after seeing another post about them and that it had an Atheros 9331 and such but it's an updated version now. I can't find anyone who's already done all the work already on this one  . I soldered on some wires and can at least power it up and see serial output but it doesn't drop to a login prompt at the end. I removed the SPI flash and dumped it but it doesn't look like it has the actual OS on it from binwalking it, however the board wouldn't boot without it installed. This is going to be more work than I hoped I think. I guess I'll remove the RF shield next and see what's under there.
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May 3, 2020 05:17
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What's the entropy in the flash? If it's high, it's encrypted, and you'll have a bunch more work on that. Rad project, though. You probably already know about the Sonoff smart plugs that are running ESP8266 microcontrollers that have an open source alternative available
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May 3, 2020 05:33
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Forseti posted:Well I ordered a TP-Link HS-100 smart plug for $10 after seeing another post about them and that it had an Atheros 9331 and such but it's an updated version now. I can't find anyone who's already done all the work already on this one Oh hey I literally took that apart before, you might be thinking of me I was able to get a linux prompt (and via that turn on an installed telnet server) and get the big ol' binary blob off it to analyze. That was like forever ago though so I don't remember much. It definitely looked very different from that one so not sure I could help much anyway.
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May 3, 2020 05:54
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https://dirtypcbs.com/store/cables/about I've never used this service but you can learn about different generic cables on their page, buy them, get a cheap sampler bag, etc
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May 3, 2020 06:23
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Shame Boy posted:Oh hey I literally took that apart before, you might be thinking of me Nah someone linked it in the 3d printer thread they other day and I saw the Atheros and decided to have a look. I found this site though and it looks like the v2 version like this has some weird Qualcom MCU with a Tensilica core and is waaaaay punier than the v1 hardware. I guess that's why it's $10. I found this fccid lookup site which is pretty cool though. https://fccid.io/TE7HS100V2/Internal-Photos/Internal-Photos-3476540 The brain is now a QCA4010 https://www.qualcomm.com/products/qca4010 Not even a transformer now, I guess it's a capacitive dropper or plain old resistive dropper for the digital power supply now. Relay is WRG, never heard of them
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May 3, 2020 14:39
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ante posted:Put a 40 or several 40-pin FFC headers on there. You'll have to spin an adapter board that breaks out a different FFC connector to 2.54mm headers or whatever you like, but that should only take half an hour I generally hate FFC, but you do have a point. Adafruit sells cheap adapter boards too. Main downside is that the cables aren't very flexible, but if I can get the connectors to be along the edge of the board that shouldn't be an issue.
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May 3, 2020 14:47
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thinking of grabbing some copper-clad pcb board but specifically for loving around with manhattan-style + other weird obsolete ways of assembling electronics, to be a fancy lad *dusts off shoulders smugly* i’m into some pretty obscure historical methodologies of circuit fabrication, maybe you’ve never heard of them
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May 3, 2020 19:15
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ANIME AKBAR posted:Any ideas? Go to a 1mm pitch rectangular connector, then build a cable to convert to the male pin you want out of pre-crimped leads?
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May 3, 2020 19:38
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surprised i’ve never run into anything like this yet: flexible plastic sheet-based PCBs. an inkjet printer deposits a catalyst where the traces should go, and then the whole thing goes in a plating bath- copper is deposited only where the catalyst is, so it’s the inverse of most conventional PCB manufacturing approaches. gotta use low-temp solders, but that sounds acceptable in exchange for a fully-flexible pcb made in a way that’s fairly accessible and scales v well down to small production runs
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May 3, 2020 21:35
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