So, I finally got the RFID kit (originally purchased at Maker Faire 2010) working. The original kit came with an RFID tag incompatible with the reader. This is why I hate buying things from MakerShed.
I am interested in experimenting with RFID, because it seems like there are a lot of uses for proximity sensors that can be identified uniquely. Turns out that the style I’m using (Mifare, 13Mhz) also have 1k of onboard EEPROM. I’m not sure how I’ll use that yet, but it seems like a promising feature. There’s some authentication understanding that I need (although I can read and write without authentication, too, to start…), and of course I need a project.
Additionally, I wired up a Hall Effect (magnetic) sensor; it lights an LED when the south pole of a magnet gets close. I’m going to use these on the CNC machine for home switches (and maybe limit switches, too — we’ll see). I have the circuit breadboarded up, I just need to build them now.
I also spent some time getting a solid understanding of “the basics”. Hooking up an LED comes pretty naturally now, but setting up an LED to work when I touch a pushbutton — yes, it’s simple, but it’s an “electronic code fragment” that I don’t really have committed to memory yet. Add to that a circuit to turn on and off an LED using a NPN transistor. As I was going through this, I figured out that the switch and 2 LEDs on the Adafruit Protoshield are not designed to work with each other (you can’t hook the switch directly to the LED; the LED needs to have its exposed pin taken HIGH (like you would from a DigitalWrite() on the Arduino, its intended purpose), and the switch drives its exposed pin LOW (like you would want for a DigitalRead() on the Arduino). One could throw in a transistor as an inverter, but that clouds the basic circuit knowledge that I was trying to gain.
So, I breadboarded up the transistor-LED-button thing from scratch, tried out a few things, couldn’t get it to work, and had to consult an online diagram to get it going. I’m not sure how much I should be experimenting on my own and how much I should be consulting references about this sort of thing. I feel like I should be able to take a datasheet and start hooking up wire to get things working, but I really am quite good at copying online schematics onto a breadboard…
Next, I’d like to play around with some ICs. 555, maybe some of the more famous amp/comparator/inverter, etc. stuff. I do want to figure out transistors, though. What’s up with PNP again?
Anyway, it’s good to be back on the breadboard again. I still need a project.