Devboards final destination:  drawer or circuit? - Page 1
Forum section: electronics / general

author: RoGeorge
author_rank: Super Contributor
timestamp: August 22, 2023, 05:44:05 am
content: I suspect most of the devboards/modules will end up unused.Would like to hear or see how you make an use of them.Do yours end mostly in a project, or in drawer?

author: hans
author_rank: Super Contributor
timestamp: August 22, 2023, 07:49:20 am
content: Drawer.They are my go-to boards when I want to run some code on a particular chip or peripheral. I like them to be free of old luggage so I can get to work asap.This is for me worth their cost, and even though they end up unused, they have been used effectively IMO.If I proceed to use a project for longer, I will order parts and design a PCB for them. Many cheap PCB mfgrs out there, .. only costs a few hours and 10s of $ to get a more integrated design working, which can be more easily tugged away in an enclosure or use the right peripherals I want to use. Most cheap devboards like Nucleo or Arduino are so minimalist that they don't feature anything at all, and I don't like stacking daughter boards onto devboards with pinheaders or extending with jumper wires because it becomes a clumsy or bulky mess. The only way I can see that work, is to mount everything on some sheet or panel so its physically more solid.. but I don't have time to make that nor space to store it.Of course for an experiment its fine, but it needs to be torn down before stored away.

author: DiTBho
author_rank: Super Contributor
timestamp: August 22, 2023, 10:48:20 am
content: ... twenty five years ago, I had to prepare an analog circuit to make a kind of "kitchen oven" as school project, a closed loop device you would probably make with an MPU and a thermocouple (1..300 C) combined with a dedicated chip that does all the sampling and filtering work and presents the data as a digital stream, but I had to use analog parts, so I made a classic operating circuit, with transducer followed by filter integrator, followed by a PID stage with the classic Gloop along the branchwith feedback and forward block, that also able to quickly reacts to maintain the temperature at the front of the door opening.And that was fine as both fully working and fully covered by the theorical lessons.Then I wanted to convert the continuous equations written according to the Laplace transform (therefore according to the classic second order differential equations that describe how a body heats up and cools down, all then followed by classic PID equations, with the integrative part at saturation), into discrete equations written according to the Z transform, which are *THE* form you have to use with MPUs and DSPs.We are talking about the late 90s, in those days there was no Arduino, there were no cheap evaluation boards, everything cost in the order of ~1000 euros, too much for a student's budget! and CAD was also something I couldn't afford!EagleCAD wasn't available at the time, and even if it was, I didn't have any internet connection to download it.The only option was OrCAD for DOS, which ran on crappy computers in the school laboratory (386 with a shitty video card), and it was not possible to install it on the home PC (a 486 with a second hand ET4000 graphics card) because it needed a hw key.So, ... I had two options: either let it go, I had already got a good mark with the analog circuit that I had delivered, or ... try to create an MPU-eval-board in the laboratory but using the free hours in the afternoon.looking at the timetables, I discovered that the laboratory was practically always in the afternoons, and there were no teachers in on { Tuesday, Thursday, Friday }.Boooom, free laboratory for +2+2+2=6 hours/week!!! and that's why I decomposed the project into sub-modules! with an approach that today is very reminiscent of the various "breakboard modules" that can be bought on AdaFruit.A module for the LCD, a module for the ADC, a module for the DAC, ... in my case a module for the CPU, one for the RAM, one for the ROM, one for the serial, one for the motherboard into which to plug all the modules.There were no cheap "PCB services", and I was only able to make 1-side PCB, a nighware when you have 8Mhz clock and 8bit data/16bit address (64Kbyte addressable) parallel bus as rooting is very complex without vias and you cannot place the proper "ground" and "Vcc" planes; anyway, making small PCB in modern "breakout" way was a successful solution as this way if a PCB was defected or bugged, or had bugs, I could only redo that and not all a BIG PCB over again!Since I didn't have the faintest idea of how to implement such a digital system from the know/how on a circuit made entirely with op amps (I was reading the intel 8031 evb guides, cloning their schematics), nor of how the Z transform works, nor of what repercussions it has on the hw and on the sw, in my case ... the total lack of an FPU, and the possibility ' calculation only at 24bit fixed-point through software support, I was also evaluating whether or not to add an external FPU... always as a floating-point "module".In the end I just reduced the constraints to much more relaxed response times, and sampled the S-transform through a two-sided transform, so I implemented everything with fixed-point.I don't know how, but it worked! but I wasn't rewarded with some praise, on the contrary when they discovered that I was using the laboratory in the afternoon without any authorization, they gave me a punishment. I still remember fivty five minutes in the school principal office and her long scolding -"if you had hurt yourself, since you were alone in the laboratory, with drill presses and PCB cutters, as well as an acid tank to produce PCBs, you would have gotten me in serious trouble!" - mainly she said.Very severe woman, not very understanding, worse than a schoolmarm!* * *Since then I've always bought ready-made development boards, or hacked existing stuff, and I've never built anything from scratch to test particular algorithms or features of chip samples.But one thing is certain: if I start working with a development board as a hobby, I never leave it unused for more than six months. So I choose well what to work on.

author: nctnico
author_rank: Super Contributor
timestamp: August 22, 2023, 11:33:53 am
content: Quote from: RoGeorge on August 22, 2023, 05:44:05 amI do the most evil thing conceivable with devboards: I put them in my excess electronics donation box which I then 'sell' to another electronics enthousiast to add to his/her hoard. It is as evil as giving heroin to an addictI just can't get myself to bring good parts to the recycling station.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 22, 2023, 01:22:08 pm
content: I would say that's a cruel thing for you to do, if it weren't for something even more cruel happening all around: the EE waste bins in any shop, required by law to properly dispose electronic waste.Only from the last week, at the corner grocery store:- a wireless mouse thrown away between empty batteries, had nRF24LE1 (SoC 2.4GHz transceiver w 8051 MCU core), couldn't resist reprogramming that, cobbled a FT232R programmer for it to foul around with its optical sensor.- couple of days later, spotted an intriguingly shaped thing (https://duckduckgo.com/?q=jawbone+up&iax=images&ia=images), took it for investigations. Turned out it's a Bluetooth LE accelerometer bracelet from a now defunct company, Jawbone. It's one of those rare BTLE devices were the encryption key is exchange OOB (Out Of Band, as in not through radio, here one has to plug the bracelet into a mobile's phone audio jack, with a certain proprietary App running, an App with a now discontinued cloud service). It's all sealed in rubber and, while there are a few online teardown videos (including one by DaveEEVblog #412 - Jawbone UP Pedometer Teardown), hacking that will be quite challenging without destroying the thing.It's very tempting to make a Bluetooth sniffer and try to hack that bracelet. Only for the thrill of it, don't need a BT bracelet (i.e. have a boughteZ430-Chronos wristwatch/devboard from TIwith many more sensor, yet never wear it). I like reverse engineering things, even if most of the hacking attempts are unsuccessful. The process is always an interesting deep dive into whatever wabbit hole.- yesterday, seen a nice white box of just the right size as an enclosure for my RPi:https://duckduckgo.com/?q=serioux+SRX-WR150WH&iax=images&ia=images,turned out to be a small router, but looking inside discovered the same CPU as on this Olimex boardhttps://www.olimex.com/Products/OLinuXino/RT5350F/RT5350F-OLinuXino/resources/RTF5350F-OLinuXino-UM.pdf, so yet another devboard.This free-devboards situation is getting out of hands quick!

author: DiTBho
author_rank: Super Contributor
timestamp: August 22, 2023, 04:11:38 pm
content: Quote from: RoGeorge on August 22, 2023, 01:22:08 pmthe difference between "devboard" and "repurposedboard"devboardsare made for the explicit purpose of being friendly with IO, fully documented, flexible and expandible, covered by examples; pro-devboards also come with a built-in-debugger/loader/monitor, and, in my case, with headers for ICE and LA. In the past it was *THE* difference, and we paid a lot(1) for these features, expecially in avionics. These days, there are cheap MPUs and DSPs around, and their evbboard offer a part of the features I listed but they are very cheap.a "repurposed board" is... something that was designed for one purpose and is modified to do other things. So it's undocumented, you have to reverse engineer it to document it, it's not covered by any development software, unless it's running u-boot or similar (able to load a file from the serial, or from the network), it's not flexible, it doesn't offer LA headers, and it usually doesn't even offer an ICE header. Usually there isn't even a serial port. If you're really lucky, you can find hidden pads to solder a jtag or SWD connector and TX and RX signals to a TTL TO RS232 adapter to have a console.they are not synonymous at all(1) e.g. my PPC7410SEQ, 5000 USD from Newark without ICE and LA.

author: AndyC_772
author_rank: Super Contributor
timestamp: August 22, 2023, 04:28:01 pm
content: I have a pile of the wretched things, STM32 mostly. I often pick up a Nucleo board so I can start software development while I'm waiting for new hardware to be prototyped, but as soon as the hardware arrives, I can move straight over to using that, and the ST dev board becomes instantly obsolete.No doubt they'll fester in a cupboard until the day I retire, then they'll get scrapped in the great clear-out when I reclaim my lab.

author: globoy
author_rank: Frequent Contributor
timestamp: August 22, 2023, 04:36:47 pm
content: Last year I did the evil thing nctnico does. I purged myself of a lot of stuff for cheap in lots on ebay. But I still have a lot of electronics left over so I started a personal project I call "Use It Up" where I make useful gadgets for myself and others with the caveat that at least 95% of the components have to be from my existing stock, even if it means making sub-optimal design trade-offs. There is no way this is efficient use of my time but it's a mental challenge and supports my desire to be somewhat responsible so it amuses me. I'm also a little motivated because I know that when I die most of this stuff will be going straight to the dumpster.So far I've built a DC-DC UPS for my home's networking system (modem, router, switch, wifi APs), a big USB battery around a Maxim dev board and some little test gear widgets. In progress is a little Galaga console for a kid.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 22, 2023, 05:06:47 pm
content: Quote from: globoy on August 22, 2023, 04:36:47 pmThat's the spirit, I like the idea!

author: Infraviolet
author_rank: Super Contributor
timestamp: August 22, 2023, 08:01:52 pm
content: The trouble is there seems no way to use up certain types of part without buying a whole load of extra parts, all of which will come in minimum quantity largr than the number you'll need for working within a circuit design alongside the part you are trying to use up.