A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
MIDI Laser Show
Scott Coppersmith presents laser show controller based on dsPIC
This well-designed project features a dsPIC30F2010-based controller for a two-axis laser show. The controller receives input as MIDI data. It controls X and Y beam deflection mirrors attached to open loop scanning galvanometers.
Author says: "I came upon two of these galvanometers at a ham radio swap meet several years ago. One is made by General Scanning, and the other by MFE Instruments. They are both open-loop dual-coil devices. MFE was a subsidiary of StockerYale Inc, and discontinued their galvanometer products in 2006. Information on General Scanning products can be found at: https://www.gs-scanners.com/ These “galvos” are rather large and slow by today’s standards. They will only operate to a maximum frequency of about 100 Hz, and they draw a few hundred mA at maximum deflection angles. This means I can’t draw spectacular megapixel equivalent images, but I can make an attempt at some serious Lissajous figures with the correct input waveforms. I’ve powered them from small computer amplified speaker systems in the past with PC generated waveforms without too much trouble, but small 8-bit micros never seemed to have enough processing power or speed to get the job done. PWM square waves don’t make very good galvo drive waveforms. The dsPIC30F series, however, is fast enough to both decode the required MIDI instructions and output the waveform data via the SPI bus to a MCP4822 DAC."