I’m working on building a digital vehicle compass, using the Honeywell HMC5883L three-axis magnetometer as a sensor. Answering the question “Which compass direction am I facing?” from the raw sensor output data is somewhat more complicated that you might expect. This is especially true when using a microcontroller like the ATTiny85 with extremely limited memory. Read on for a discussion of the problems involved and my solutions.
Month: February 2014
I2C with ATTiny85 on Adafruit Trinket
The Trinket microcontroller from Adafruit Industries is a tiny and inexpensive (US$8 for a single unit) way to control your electronics projects. One of the coolest things about it is that you can do I²C (and communicate to lots of inexpensive sensors and displays using only two pins) and still have plenty of room left over for your code in the ~5.5KB of flash on board.
Read on to see an example of how to do I²C communication on the Trinket (or anything with an Atmel ATTiny85) while shaving every possible byte. Also included: driving the Adafruit Mini 8×8 LED Matrix with I2C Backpack.
BeagleBone Black PRU: Hello World
This article presents what is meant to be the simplest possible example of using the PRU (programmable realtime unit) on the BeagleBone Black single-board computer. The example program has no inputs and no outputs; it does nothing other than delay for a fixed duration then exit. Read on after the jump…