Category Archives: Arduino

RFID Door Opener, Part 1

Inspired by the numerous door openers out there, I decided I’d give it a shot (ok, really, I was just looking for something to do with my spiffy Parallax RFID reader). At first I was hoping I could use the RFID tag that opens the entrances to my apartment building; however, those turned out to [...]

USB Power Shield v2.0

The new USB Power Shield boards (rev. 2.0) have just arrived from BatchPCB! As always, they were quick, great quality, and they even sent me a few extra! Awesome service. Version 2.0 has some major revisions since v1.0, including: Smaller Size – cost is determined by size, so I brought it down to the bare [...]

Sketching with the USB Power Shield

So you have a USB Power Shield (or anything that uses a latching relay). How do you control it in an Arduino Sketch? Normal relays are pretty simple – supply voltage/current to the coil and it generates a magnetic field, which pushes the switch to the ON position. You only need one pin to run [...]

Success! USB Power Shield v1.0

A special envelope arrived yesterday from BatchPCB – the envelope containing the prototype board for the USB Power Shield v1.0. Or should I say prototype boards – they were kind enough to produce two, even though I only ordered one. Consider me a happy customer, especially because the boards work. That’s right, the very first [...]

First USB Power Shield Prototype on the Way!

After toying with the relays and Arduino I found that the diodes weren’t necessary – especially since the relay is latching, and current will be flowing both ways, so putting a diode in each direction would just create a short. As such, I made some modifications to the board and put it into Gerber files [...]

Now with 100% more relays!

The arduino USB Power Shield has moved over to a relay design, to eliminate the voltage drop the transistors would have caused. Ports has dropped to two because a) no one needs to control four 5V devices, and b) the relays are latching and need two pins each. The board isn’t done – I’ve ordered [...]

USB Power Shield

I really wanted there to be a complete solution for the Woot-Off lights project that could be almost plug and play for the end user, so today I drew up a schematic and a board for a USB Power Shield for the Arduino. It pops onto the Arduino like any other shield, and by controlling [...]

Woot-Off Lights – in Python

The Woot-Off Lights project continues to slowly progress. Over the weekend we moved over to Python for the coding, since that’s the language Alex is most familiar with right now (especially in networking). Serial control of the lights in Python took longer than expected – we could have saved over an hour of troubleshooting had [...]

Driving Speakers with Arduino

In my quest to try out everything the Arduino can possibly do, I decided to hook up a buzzer and try messing around with generating some tones. Since my little 8ohm buzzer seemed to have gone missing, I substituted one of Sparkfun’s audio jack breakout boards and a cheap pair of earbuds I had lying [...]

Woot-Off Lights Schematic and Hardware

Here’s some details about the hardware setup for the woot-off lights. It’s exactly as I described in the first post – this just includes the schematic and goes a little more in depth. Let’s take it from left to right. USB input to the Arduino to send serial data. The current from the USB port [...]