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#210 – Risky Components and Hardware Innovation – Slipshod Shack Shutdown

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SurfaceMount

Thanks to Eric Horst for the pictures of the resistors.

Comments

  1. Chris and Dave started talking about grid level storage. I grew up near Grand Coulee Dam (http://en.wikipedia.org/wiki/Grand_Coulee_Dam), which is my ideal of a great powerplant ecosystem. First, its a huge hydro plant (6.8GW). Second, it provides irrigation to an otherwise parched eastern Washington. And third, it pumps water up the hill at night, then reverses the flow during peak use.

    To Dave’s point on efficiency loss, but the river doesn’t care. It just keeps rolling along. I heard a concept in Cleveland, to pump water between the great lakes as storage, but the source of power to run the pumps drew on coal fire plants. That was nuts.

  3. Dave, The Simulator for the tablet is called EveryCircuit and it has been an incredible learning tool for me. The free version is fantastic and the paid gives you a larger prototyping area (maybe enables more options too, not certain).

    It’s pretty handy and very easy to use.

  4. What? Did Chris mention an OSHPark-like service in Europe? Who can tell me more???

    • I second that! Currently looking at pcbshopper.com for a 5cm x 5cm 2 layer board and I’m getting $14.90 (incl. shipping to Europe) for 10pcs. > 30 days shipping time 🙁

      • I must be missing something. $15 for 10 boards this size would constitute a huge discount at OSH Park.

        • It’s cheaper, but very much slower (if shipped from europe). And also cheaper in import handling fees. (Here in Denmark, I have to pay about €20’s fee on top of the import tax and VAT on orders more than €11).

  5. As the software guy, please, please, please come up with schematic standards.

    Some of the things that piss me off are the disconnected component method with the processor over there, uart over there, connected by white space and net lists. Sure it’s correct, but I can’t find the stuff connected to the SPI bus if they are spread across 5 sheets and stuffed into random corners. Just run that wire that extra centimetre, please, they’re almost free today.

    No block diagram. Processor broken into two or more parts. Arrrrg, please, the things are meant to be read by two people, me and the board layout package, and Altium doesn’t give a flying handshake, so draw it for ME! (or worse yet, you in a couple of years when YOU have to debug the stupid thing, you’ll thank yourself)

    BTW, yes, the best “coders” use coding standards. Indian Hill and MISRA are popular (MISRA especially in embedded systems). MISRA was used as a basis at the JPL and the Joint Strike Fighter project, and has been adopted by medical, nuclear, and other high reliability industries, as well as the original automotive industry.

    In many companies you MUST follow the style guidelines for one good reason; if you check in code that has one character changed, the fix is easily checked (you do code reviews, don’t you?). If you routinely reformat the code to comply with “Bob’s personal leet style with 5 spaces instead of tabs and modified Whitesmiths indenting”, the fix is lost amongst the useless clutter and everybody else on the project will poison your Dr. Pepper.

    There are lots of style guides out there, put your ego on hold and pick one (and if you use gotos, sleep with one eye open, the maintenance people know where you live).

    • Written like someone who has dealt with both bad code and bad schematics….well said!

      I definitely agree with the part about “coming back to the project” after many months/years. I have often looked at something I did a few years back and cursed former me. But more often I’ve looked at others’ schematics for support and felt the pain there.

      • I think the resistance of EEs and CSs to use best practices comes down to ego or the dreaded “I’ve always done it this way”. I don’t think anyone benefits from someone who has shut down learning.

        I find it refreshing to hear, on podcasts like yours and the Embedded podcast, that some people feel like frauds because they can’t get stuff working as quickly as they should. I feel that way too, and look for ways to progress my abilities, like finding a good style guide, code reviews, using RTOSs and version control systems, and not using PICs and global variables. This way I can spend less time debugging stupid mistakes.

        This has a lot to do with what the Embedded podcast called “Being a grownup engineer”.

  6. Coding standards are also a big thing in open source projects. Most open source code bases of any appreciable size have style guides or coding standards (though generally not as stringent as MISRA or JSF).

    I think the reason why they’re so big in SW (and not so big in HW) comes down to use case. A coding standard is incredibly valuable when there are a lot of individuals all contributing to one project. The coding standard ensures that the entire codebase is readable to everyone involved, that changes are easily reviewed and verified, etc.

    Hardware schematics, in general, involve fewer simultaneous contributors. Yes, it’s a bit of pain if you inherit a schematic that was designed in a style completely contrary to your own. But contrast that to the idea of trying to make simultaneous edits to a schematic with a coworker who uses a contrary style, and you will get a sense of why it’s so much more important to SW people!

  8. The notes above say:

    “One example given was board share programs like OSHpark (we had @Laen on show 149) There is also a new Aussie version called breadboardkiller. ”

    I think there’s a composition or parsing error here. The Aussie company has no board sharing program as far as I can tell from their web site. I hope I’m confused or otherwise wrong. Not that I think the OSH Park board sharing program is a great resource as it currently exists. There is no communication mechanism for problems and infinite motivation for “shipping the *untested* prototype”. But I know Laen means well and want him to succeed. OSH Park is a fantastic prototype PCB vendor!

  10. I don’t know of a complete standard specific to board level schematics but there are a few things I’ve worked with which go in that direction. IEEE-315-1975, which is incorporated into ASME Y14.44-2008, covers schematic symbols, abbreviations, and reference designators for schematics. It also includes a very complicated but useful way of naming things hierarchically when creating large assemblies of subassemblies of components. MIL-STD-100 and MIL-STD-863 also have some useful bits on the contents of engineering drawings in general and schematics specifically.

  11. BTW , They still use MFD in India . All the local retailers selling spare parts still only know MFD here
    apart from those who know what it is .