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Great Maker Session

On Friday, I sent a note to the Maker mailing list inviting people to an unboxing of the stuff I ordered for my balanced aquarium project. Everything has come in, except the CO2 sensors, which should arrive in a week or two. I promised to bring the box, unopened, so people could participate in the joy and mystery of opening the box.

Earlier in the day, interspersed with my other tasks, I finished unboxing the rest of the Galileo development boards I received from Intel. I tested them and updated their firmware, so they'd be ready to go.

I got out an LCD shield from DF Robot first. It looked lovely and snapped seamlessly into place. But when I connected the power, it didn't seem to work. I checked the connections and it powered up for a minute and then was down again. I found if it wasn't connected quite solidly it seemed to work, but as soon as I pressed down on it, it stopped. Then I realized what it must be: the shielding around the ethernet jack causes solder points on the bottom of the shield to short out. After a bit of experimentation, I cut out a bit of plastic tape and covered the top of the ethernet jack. Then I could connect it solidly and it worked flawlessly. Well, it powered up, anyway.

When I copied the test script in from the DF Robot wiki, it didn't work. Nothing seemed to happen. So I googled a bit and discovered this post which describes how to replace the Liquid Crystal library with an updated version. After initially putting it in the wrong place, I fired it up and, Success! I was able to diplay messages on the LCD.

Next, I got out one of the pH probes and connected it to the risers on the LCD Shield -- how wonderfully convenient! You can just plug it in! I grabbed the test code for the pH probe and munged it into the LCD display code, so it would show its output on the LCD. Nothing: a pH of 0. I had remembered seeing something about the LCD shield using analog pin 0, so I had switched to a different sensor pin but then realized that I was just counting wrong. I moved the plug and, Success! I was getting pH readings! And that's where I how far I got before it was 5pm and time to open a beer, sit back, and talk about other things.

I was initially skeptical that the data were good, because the pH meter was proposing a reading of 3.83 for its buffer solution. A bit of reading, however, suggests that the reference buffer for storage is supposed to be pH 4.01. That sounds like we're in the right ballpark anyway. So far I'm very pleased with everything from DF Robot: quick service, good prices, and good documentation.