RAREblog

Over the weekend I spent some time on the LCD text display using the LiquidCrystalFast library. There's still work to do, but the core hardware is working. When I've finished the hardware and software I'll post the details but first I thought I'd document the mistakes I made and the processes I followed to troubleshoot the project and get it back on the rails. My normal workflow for a new hardware design takes things in small steps, with lots of testing as I go. I start with a rough design, which may be on paper or in my head, and then I breadboard and test. Once the breadboarded version is working I transfer the design to stripboard or to one of Adafruit's wonderful PermaProto boards , and test again. If appropriate, I then design a board and send the files off to a PCB fab shop to make the first PCB version, which may need further testing and revision. My First Mistake This time I took a short cut. I've built a dozen or so Arduino clones on stripboa...

One project I'm hoping to complete in the next day or so is an I2C-based Text LCD for use with the Raspberry Pi. Why bother? After all, the Pi has an HDMI output, and it's easy to connect the Pi via Ethernet or wireless. The problem is that there are situations where you really need a stand-alone display. Stand-alone Pi Projects If you're building a battery-powered  stand alone project you may need an output mechanism that's a bit more informative that a few flashing LEDs,  your power budget may not run to WiFi, and you may want to use what you're making in an environment where a network-based solution is not practical. Another application: running a physical computing course It may be hard to connect to the Pi because you don't know its IP address. Earlier this year I helped to run a couple of workshops covering physical computing on the Pi. Practical considerations meant that we couldn't use monitors for each Pi, and we had to connect to the lo...

A few days ago I started exploring the teensy 3.0 . I'm keen to see if we should consider using the teensy for C3Pi , so I want to get more familiar with the teensy hardware and the development environment. When you install teensy's extensions to the Arduino IDE you are given a chance to install a number of additional libraries that have been tested on the teensy family. One of them - LiquidCrystalFast - caught my eye and I decided to explore it in more detail. The LiquidCrystalFast library LiquidCrystalFast is yet another library for driving text LCDs based on the ubiquitous Hitachi HD44780. I love these displays, and so do many hobbyists; a old post about an  Arduino DVM with LCD display  is one of the most visited pages on this blog. The standard Arduino LiquidCrystal library works pretty well, but suffers from two minor issues. The first is that it doesn't work as it should for 4-row 16-column displays. (It's fine for 2 row displays and for the 4-row 20...