Tuesday, January 28, 2014

Post 44: New Stuff

I guess my habit is serious. I just got my second Model B, Rev 2 Raspberry Pi (so I can have a "stable" one and one to mess with).

I received the order from www.mpja.com (mentioned in the previous post). Delivery was quick and everything worked (but the default delivery by UPS Ground is pricey -- I switched to U.S. Mail).

I particularly like the tiny PIR detector -- about 1/2" across, $3.95.
Note that the connector pins point straight back. The whole thing will fit inside a 3/4" OD plastic tube. It lacks adjustment pots but works with my existing software.

Now I've ordered this breadboard and connector:
The GPIO pins are labeled. Plus 3.3v, 5v and Ground are already connected to the edge rails. And unlike other such connectors, only one row of pins are covered up. I could wish it was less than $19.95.

Things I'd like to have:
1. A selection of longer Pi camera ribbon cables. The camera works fine but the 15 cm wire is a pain. 
2. A way to get from the solderless (but easily messed up) breadboard to something secure (if not permanent). Soldering a proto-board will be a chore. Maybe there could be a breadboard that works like a zif connector -- flip the lever and the jumper wires are clamped solidly. Eh?

Thursday, January 9, 2014

Interesting Pi-Related Web Retailers

A site with a large variety of interesting stuff, especially sensors -- some that I haven't found anywhere else. These include devices for detecting various kinds of gas leaks. Also seemingly low prices on some items -- e.g.: PIR motion detector for $3.95. They also have a huge variety of power supplies, junction boxes, motors, etc.

As the name suggests, this is a tool for remote medical diagnosis. The site claims that up to 10 biometric sensors can be simultaneously attached. If the patient and doctor both have broadband and webcams then the patient could seemingly have an "office visit" without going to the office. The site claims that the "platform" (their term) is available for order starting 1/7/2014 for 450. Add a well-equipped Pi and the whole remote setup would be under $750. Chickenfeed next to the current market. It also occurs to me that their platform contains all the sensors that one would associate with traditional lie detectors!

. . .

Standard disclaimer: I have no financial interest in either of these outfits and I have no information on their reliability. However, I have ordered a few things from mpja and I will report back if I learn anything interesting.

Wednesday, January 8, 2014

My Pi-Controlled LED Strip Porch Light Project

I bought these online for about $25.
5 meter, 18 watt LED strip and 30 watt 12 volt power supply

I plan to stick the LED strip under the outer edge of the soffit. These things are surprisingly bright. And the length is just right to span my deck, the front door and the steps up on either side. I also ordered (but haven't gotten yet) a new PIR motion detector that is small enough to fit inside a 1" PVC pipe ($1!). I need to recess the PIR to limit its angle of view (otherwise it would be constantly tripped by blowing plants or varmints). The detector will be pointed so it covers someone standing in by the front door. In simplified terms my Pi program will work like this:

Only if it's dark:
  Test the PIR every 3 seconds
  If the PIR has detected motion:
    Turn on the LEDs for at least 30 seconds, continue if there is more motion
There is a handy soffit vent to bring out the PIR sensor and 12v for the LEDs. This vent is only about 12' from my Pi. I plan to run 5 22 gauge wires, 3 for the PIR (5v, ground and 3.3v signal) + 2 12v for the LEDs.

As an over-ride to my program sketched above, I have already programmed a web interface that will turn the lights on/off from my iPhone.