Posts tagged crystal ball lamp
Crystal Ball Lamp, part 3
Nov 20th
—— The Electronics ——
In this post I’ll discuss the design of the electronics part of the Crystal Ball Lamp.
The lamp is controlled by an Arduino Mega microcontroller board. I was originally going to use a less expensive Arduino Pro Mini. It doesn’t provide enough PWM outputs for the nine LED channels I wanted to control, but I could do some multiplexing to get an approximate PWM signal to each of the channels independently; it would complicate the circuitry, but I could endure that if it saved enough money. As I worked through the design, I began to get concerned about the small amount of RAM available on the ATmega328 used by the Pro Mini (2 KB), fearing that this would not be enough to run my lightshow programs for nine channels and be able to run a scaled-down graphical-user-interface through the oLED display (mostly just menus that a user scrolls through). Furthermore, the Pro Mini only has one hardware serial port. I wanted to communicate with two serial devices – the XBee module and the oLED display – so with the Pro Mini one would have to be handled through software, which would use even more RAM and slow down the performance of the whole device. So with all these concerns, I just went ahead and splurged on the Arduino Mega. It had more than enough PWM outputs for my nine channels, more RAM (8 KB), and more than enough hardware serial ports.










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