Saturday, September 25, 2010

Something I'm Proud Of

Engineers are supposed to make things, right? You'll cruise the hobby blogs and read about all these cool projects that light up and/or tweet things - everyone seems to be making something nowadays. I'm not so great in that respect. I really haven't made anything apart from my job. It's a little embarrassing, but I don't really get off my butt unless someone orders me to do something. But then I'm great - I make scripts. PCBs, code, you name it.

Well it turns out that lately I've actually accomplished something - and it all started with a problem. While working on a microcontroller design at work I was readily infuriated by breadboards. You just can't get away from them and you shouldn't try. Everything really out to be breadboarded before it's finalized - otherwise you'll have loads of incorrect PCBs laying around and lots of wasted money. But breadboards are hard to work with: wires pop out, you can't put surface mount components on them, they don't have nice modular connectors and you can't always stick a probe in the holes to see what's going on. So I made something to fix that problem for me.

This little doohicky is a breadboard test point/connector adapter. It has a row of 8 pins that plugs into your breadboard and then connectors for the power bus (there's two different configurations of power busses that i've seen - .1" pitch and .15". It has holes for both). First, it has 8 surface mount LEDs for each of the pins making it very useful for status displays. Second, it has a 2x5 connector that will fit a standard IDC cable plug. I have plans to make an IDC to male pin cable that plugs into it. Third, it has two sets of test points - there are male headers for logic analyzer female plugs to fit onto (along with the obligatory 9th connection - ground) and then there are high profile test points that work great with scope probes. And also for the scope probes there are four high-profile test point ground connections. No more silly jumper wires to the ground bus on the breadboard. All of the test points are isolated from the breadboard by 10K resistors. That way, if you accidentally short two test points together (perhaps one that is connected to ground and another to +5V) you won't break whatever is connected to those pins. If, for instance, you do have the worst case scenario and +5V shorts to ground, you have an equivalent 20K of resistance between them and nothing short circuits - just 2.5mA flows through the connection. Lastly, there is a 1.5A resettable fuse between the breadboard VCC and the VCC on the IDC connector, so if something you accidentally connect the +5V from the IDC connector to ground the fuse will trip and not hurt your power supply on the breadboard.

I plan to sell these at... well, wherever will take them. Sparkfun, Ladyada, etc But not yet. There are several design problems that need to be ironed out. A bit more parts selection, maybe a few more components and this board will be ready to sell. I hope everyone else is as excited as me.


Anyone? Bueller?

Oh well.

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