Home > Tech geeks > A-Team moment…

A-Team moment…

As George Peppard used to say, “I love it when a plan comes together”. For those of you that are too young to remember B.A. Barracas (played by Mr. T), Face, and the rest of the crew – Talk to the hand. You probably don’t know who McGuyver was either, other than the butt of some cynical jokes.

Tonight I assembled the project box for the grant circuit. While it didn’t turn out exactly as I envisioned it (because project boxes that are 8″x2″x2″ are not readily available), it did turn out pretty good… and I can always replace it down the line, if need be. The power LED is mounted on top, and the serial download connector (the standard 3.5mm stereo jack) as well as the RJ11 jack for a 4-conductor phone cord are mounted on the sides. At some point I’ll drill another hole for the LM34 temperature sensor, which will measure temperatures in the stainless T at the grant exit, but for now I have the sensor tied to ground via a jumper.

I did wire up a quick rig to allow me to connect to power the circuit and make program updates – you can see the battery pack in the pictures above. The wires basically deliver a 5V and ground connections on pins 2 and 5, leaving pins 3 and 4 (the serial out to the main skid circuit) unconnected. Since the serial signal is on the middle twisted pair, this ensures that the grant only really works if a 4-conductor phone plug is used between the control box and the grant. The battery rig will only be necessary if I update the grant PICAXE program using the 3.5mm plug.

The program and output are pretty simple. It transmits the output string of “<G>” followed by 4 bytes – the first being the float switch states, bytes 2 and 3 are the temperature sensor reading, and byte 4 is a calculated checksum to ensure the data packet is properly received.

With this under my belt, I just need to get cracking on the circuit for the skid control box. Its probably 80% designed and a good portion of the cabling and wiring is already done – its simply a matter of settling on the trace design, etching it, drilling it, and soldering things up.

If I were a stogie man, it might be a good night to light one. Since I’m not, I’ll have to let good ol’ George’s ghost enjoy one for me.

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Categories: Tech geeks
  1. August 27, 2008 at 1:21 pm

    Nice stickers 😀

  2. brewznet
    August 28, 2008 at 12:13 am

    Heh. Yeah, those rock. I’ve got another set, although the next time I order from SparkFun I’ll probably have to get more.

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