Quite appropriately, the first board that I exposed with my UV exposure box was a timer to control the exposure. The heart of the timer is a Picaxe 08M2 microcontroller. The timer has also an inexpensive 16×2 characters LCD display (based on a HD44780 controller protocol) and a rotary encoder to set the time. The rotary includes a push button that starts and stops the timer and the exposure. An I2C I/O expander chip PCF8574 interfaces the PICAXE to the display module to save i/o pins on the microcontroller. This way even a small 8-pin microcontroller can be used. Continue reading
I’ll post a software mini project for a change. My wife asked me the other day if I would know where she could download a count down timer application. She is a teacher, teaching first grade this year, and she needed a visual timekeeper for activities in her class. The idea was to display the timer on their fancy interactive whiteboard while the kids were working on something. This immediately sounded like a project to me.
To cut things short, here are the links to the web pages. Continue reading