The folks at Seeed Studio were kind enough to send me a Grove Beginner Kit for Arduino for review. That’s a mouthful of a name for a compact little kit!

The Grove Beginner Kit for Arduino (henceforth “the Kit”, because ain’t nobody got time to type that out more than a few times in a single article) is about 8.5 x 5 x 1 inches. Closed, you could fit two of them on a piece of 8.5x11 paper with a little room leftover.

The folks at Seeed Studio have just released the Grove Beginner Kit for Arduino, and they asked if I would be willing to take a look at it in exchange for a free kit. At first glance it reminds me of the Radio Shack (remember when they were cool?) electronics kit I had when I was a kid – but somewhat more advanced. I’m excited to take a closer look, but given shipping these days means it’s probably a month away at least.

We’re all looking for ways to keep ourselves occupied these days, and for me that means leaping at the chance to turn a small problem into a slightly ridiculous electronics project. For reasons that I won’t go into here I wanted to generate an alert when a certain WiFi BSSID becomes visible. A simple solution to this problem would have been a few lines of shell script to send me an email…but this article isn’t about simple solutions!

I have a Raspberry Pi running RetroPie hooked up to a television. It’s powered from a USB port on the TV, which is convenient, but it means that whenever we shut off the TV we’re pulling the plug on the Pi. While there haven’t been any problems so far, this is a classic recipe for filesystem problems or data loss at some point. I started looking into UPS options to alleviate this issue. I wanted something with the following features:

I’ve set up my Raspberry Pi to communicate with my Arduino via I2C. The Raspberry Pi is a 3.3v device and the Arduino is a 5v device. While in general this means that you need to use a level converter when connecting the two devices, you don’t need to use a level converter when connecting the Arduino to the Raspberry Pi via I2C.

The design of the I2C bus is such that the only device driving a voltage on the bus is the master (in this case, the Raspberry Pi), via pull-up resistors. So when “idle”, the bus is pulled to 3.3v volts by the Pi, which is perfectly safe for the Arduino (and compatible with it’s 5v signaling). To transmit data on the bus, a device brings the bus low by connecting it to ground. In other words, slave devices never drive the bus high. This means that the Raspberry Pi will never see a 5v signal from the Arduino…unless, of course, you make a mistake and accidentally digitalWrite a HIGH value on one of the Arduino’s I2C pins. So don’t do that.

I’ve recently started playing with an Arduino kit I purchased a year ago (and only just now got around to unboxing). I purchased the kit from SparkFun, and it includes a motley collection of resistors, LEDs, a motor, a servo, and more.

I was fiddling around with this exercise, which uses the SoftwareServo library to control a servo. Using this library, you just pass it an angle and the library takes care of everything else, e.g. to rotate to 90 degrees you would do this: