as always, amazing....! whenever you get a chance, can you stub out a landing page for this project? great for getting more people involved!
On Fri, Sep 2, 2011 at 6:52 AM, Werner Almesberger <[email protected]> wrote: > Jon asked me to post a bit more regularly about what I'm doing. > Here's the thing I'm having fun with these days: a USB-controlled > lab switch. > > This is a fairly old idea that I've never fully implemented. The > background is that you often need to switch power, buttons, or > similar when testing a circuit. Sometimes, you need a lot of test > cycles to make a hardware bug come out of hiding. > > These days, I'm lending a hand to the debugging of the Milkymist > One rc3 boards. One of the problems we don't fully understand yet > is an occasional NOR corruption that has been observed on some > boards. One hypothesis is that this is a power management issue, > but we're not quite sure about it yet. This problem doesn't > happen very often, but still often enough that we've noticed it > a few times during testing. > > Now, power-cycling a board hundreds of times and running checks > on it is a grueling task at best. But of course, that's what we > have machines for. Hence the return of the lab switch project. > > There are commercially available USB-controlled relay boards, but > they lack a few features I'd like to have, and finding a nice > case for such boards would be messy at best. Besides, it's more > fun to do your own :-) > > What it will do: its main function is to switch a number of > signals or power lines. The power lines may have a high current. > The current design will be limited to "safe" voltages, but should > ultimately also accommodate mains. > > This picture shows a first mechanical check of the PCB: > http://downloads.qi-hardware.com/people/werner/labsw/tmp/labsw-0-pcb-mech.jpg > > The two big orange things are relays that can switch up to > ~16 A (not sure if the rest of the circuit can handle it, though. > I'm using a number of components I've sourced locally and that I > don't have documentation for.) > > On the left side of the image are four opto-coupler inputs, the > mini-USB connector, and four opto-coupler outputs (good for up to > 200 mA.) There will be a front panel that connects to the relays, > have two more opto-coupled outputs linked to the relays, three > buttons and three LEDs. > > The C8051F320 microcontroller will take commands over USB, but it > can also be given a "script" (a state machine) to execute > locally. This will allow the buttons to perform > application-specific functions. Some examples: > > - press to turn on, press again to turn off (that would be the > default behaviour) > > - turn on for exactly 1 second when button is pressed > > - turn on while button is pressed, then stay off for at least 10 > seconds > > I expect the design to evolve over a few iterations. For example, > the first version won't be safe for mains voltage, I should use > keyed sockets where possible, and I need to substitute parts of > unknown origin with things that are fully characterized and can > be ordered globally. > > The project is in > http://projects.qi-hardware.com/index.php/p/wernermisc/source/tree/master/labsw/ > > What's next: the making of the front panel. Like the PCB, the > front and rear panel will be CNC-milled. I'll (ab)use fped to do > the CAD design. Sneak preview: > > http://downloads.qi-hardware.com/people/werner/labsw/tmp/front.pdf > > From left to right: > > - channel 1/2 off-state relay output > - CH1/2 common > - CH1/2 on-state relay output > - CH1/2 opto-coupler output > - CH1/2 LED > - CH1/2 button > - system status LED, system on/off button > > This project creates a number of prerequisites on our EDA/CAM/etc. > tools and libraries infrastructure: > > - the scripts I've used so far for making PCBs were for 0.8 mm > boards. This 1.6 mm board requires a number of adaptations, > mainly to cae-tools/cameo/templates/mkmk-simple > > - fped needs to learn to output things in a more CAD-ish way. > This is the next thing I'll tackle. I'll make it output simply > in gnuplot format, which is easy to parse and to convert to > other formats. > > - various new components and footprints for the KiCad libraries, > including headers, spacers, and DIP parts. > > - my USB stack for SiLabs C8051F3xx chips will also need merging > into the better structured stack I have for the ATmega U2 > series. The latter is derived from the former, so that shouldn't > get overly nasty. > > I've also noticed that I'm exceeding the capabilities of the data > sheet viewer (dsv), because I now share data sheets with other > projects but don't have a way to reference their BOOKSHELF files. > This will need a bit more thought. > > - Werner > > _______________________________________________ > Qi Hardware Discussion List > Mail to list (members only): [email protected] > Subscribe or Unsubscribe: > http://lists.en.qi-hardware.com/mailman/listinfo/discussion > -- Jon Phillips http://fabricatorz.com/ chat/skype: kidproto | irc: rejon +1.415.830.3884 (global) | +1-510-499-0894 (sf) +86-187-1003-9974 (beijing) _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
