September 03, 2014

Soldering and testing

First up is the NeoPixel strip. AdaFruit suggest a 1000uF capacitor across the power lines, and a 300-500 ohm resistor for the data line.

The solder pads for the NeoPixel strip are pretty small. I ended up soldering the capacitor to the strip, and then soldering the red and black wires to the capacitor leads. I soldered a 470 ohm resistor to the data pad, and then soldered the orange wire to the resistor. In the photos the resistor is covered by heat shrink. The different colours of hookup wire came in handy!

Red to +5V, black to GND, and orange to digital 6. I uploaded the test code for NeoPixels, and plugged in a battery. Wow pretty colours!

Now for the temperature sensor. The Texas Instruments LM60 reports a voltage proportional to the temperature. The temperature in degrees Celsius is the output voltage minus 0.424V divided by 0.00625. It is not hugely accurate, but it does the job.

In the photos you can see hookup wire soldered to the leads of the LM60. Red to V+, black to GND, and yellow to Vout (which goes to analog pin 0 on the Arduino).

I wrote a simple program using the above formula that displays the current temperature to the serial console. It says 17 degrees in here. My thermometer thinks about 16, so for +/- 2 degrees, that's OK by my books.

Next comes the light sensor testing. I hooked this up yesterday before I had pretty coloured wire, so now of course I have to refer back to the data sheet every time I connect it.

It connects to +5V and analog pin 1 on the Arduino. There is a 100k resistor between analog pin 1 and GND.

It's a bit dim in this room, but it is light enough to see. Even so, the values I am seeing from my test program are a bit low. On the Arduino, analog pins report a value between 0 and 1023. For the light sensor 0 means really dark, and 1023 means bright light. I'm seeing values of about 10. It does get higher if I face it towards the light, but it's still a bit low for my liking. Oh well I guess I'll have to work with that.

1 comment:

Eb said...

Lyn said that a build log is like a visual arts project diary.