Author Archives: explodinglemur

Inexpensive logic analyzer

Cypress has a little USB-interface micro called the EZ-USB that can stream the state of its GPIO pins to a host computer.  This chip was used by Saleae in their original Logic product, making for a simple, inexpensive logic analyzer.

Now, it turns out, there are cheap dev boards for this chip all over eBay (in the sub-$8 range) that can be loaded with some open source firmware from the Sigrok project to turn them into a similar logic analyzer.  Unfortunately, the EZ-USB chip is a 3.3V part, and has no protection on its GPIOs.  Fortunately, there are plenty of 5V tolerant non-inverting buffers out there, such as the 74LCX245 I picked.  Add some 100-ohm current-limiting resistors, and you’ve got pretty much what you need.  So, I designed a board and submitted it to OSHPark.  Parts-wise, it’s pretty easy…two 2×10 female headers (soldered facing downward, it made the layout easier), a right-angle 1×9 male header for the probes, 8x 100ohm 0805 resistors (easy hand soldering), and a 20SOIC 74LCX245.

Can’t wait for the boards to get here so I can try it out!

Shed construction continues, slowly

Haven’t made any updates in a while, but the shed is still being worked on.  We got the roof built and sheathed, put tar paper up on the roof and walls, installed the window, and have installed wall sheathing on two walls.  There are some rain storms coming through this week, and this weekend is full of other things, so hopefully we’ll finish the walls and door the following weekend.  After that, shingles and paint, then we can start storing things!

(Sorry, no pictures this time around)

Walled in

This weekend, my dad came down and we framed out the walls of the shed.  It went surprisingly quickly, actually, despite a small snag…the 2x4s that I thought were a full 8′ long were actually 92.25″ long, cut for wall stud members (to make for an 8′ interior wall when top and bottom plates and drywall for the ceiling are taken into account).  I had planned to cut the wall studs down to make for about a 7.5′ high wall, so that wasn’t too much of a problem, but we did need 8′ lumber for top and bottom wall plates.  My dad ran off and picked up enough 8′ lumber, while I started preparing measurements.  We decided to just leave the 92.25″ studs at that length to save time, and after triple-checking measurements, cutting the framing members for the door and window, and judicious application of the pneumatic nail gun, we had four walls raised.  Even putting just a few hours here and there into it, this sort of project does not take very long…I can’t imagine spending several thousand dollars on a prefabricated shed at this point, especially since the ones I’ve seen don’t seem to be of particularly good build quality.  We’ve spent an order of magnitude less, will have a nice very sturdy shed, with a real weatherproof door and window.  I’m looking forward to the next build day!

Pictures follow…

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Shed foundation

With the help of my dad, the concrete piers for the shed were placed and leveled, and the floor frame was laid on the piers and nailed to the straps.  The plywood floor is shown sitting on top, but has not yet been attached, as I bought the wrong kind of caulk.  I’ll hit up the hardware store and get the plywood glued and nailed down, then I’ll start on the wall framing.

Pictures follow…

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The shed has begun!

We finally started work on the shed today!  Cut all the floor framing parts to the right length and started nailing them together.  My nailing technique needs work, I’m not used to hammering sideways, and my wrist got thrashed pretty quickly.  Will have to finish nailing tomorrow, or at the end of the week as rain is forecast for Tuesday and Wednesday.

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Construction plan summary

Lately I’ve been thinking about how little I use my (hideously expensive) gym membership, and how nice it would be to have some gym equipment at home to use while watching TV or when I’ve got a half hour or so of downtime.  I rarely hit the gym after work as I usually want to get home and get some dinner, and once I’m home it feels like a big outing to get all my stuff together and head out to the gym.  Having an elliptical trainer or stationary bike and some weights at home would be much more convenient.  Unfortunately, there’s no room for such gear in our not-that-big house (3 bedrooms, my wife and I occupy one bedroom as a bedroom, one as an office, and we have a roommate that has the third).  So…

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