Prop projects, tricks, and traps

I was recently caught by a problem with Apple's new iCloud features, which sync a variety of info between your various iOS devices and PCs or Macs. (I don't have a Mac.) One of these reads all of your existing IE bookmarks and syncs them around to your different iCloud devices and PCs.

The problem was created by having another app running on the PC that attempts to do basically the same thing: Windows Live Mesh, from Microsoft, part of the Windows Live apps suite. These apps monitor ...

After finalizing my build and mounting it to a piece of acrylic, I needed to sit down and figure out the cause of some outstanding jumpiness in the display. The basic problem turned out to be a lack of synchronization between the cogs doing the scrolling of the monochrome text bitmap, the generation of the color version, and the final output cog which does PWM calculation for the specified colors and sends the video output to the shift registers. Actually the first two were already synchronized ...

Thanks to Ericball for the idea, but after spending an afternoon learning how the built-in video generator in the Propeller works, I was able to realize a modest improvement in throughput over the old bit-banging algorithm, such that I can now double my PWM resolution to 64 steps and still maintain a framerate just shy of 60fps with 2 LED modules.

The video generator is really just a nice general purpose shift register itself - you give it some data to shift out(formatted as sequences ...

Finally, displaying something!

After all the stuff I described in the last post, we now finally have an array that holds exactly what we want displayed on the LEDs - exactly the right number of pixels for our LED hardware, in exactly the colors we want to display, changing smoothly as we scroll the message, and changing colors smoothly as the fader cog blends between different random output colors. However, remember that the RGB LED matrix is designed in such a way that while you can ...

Since the last article was mostly about the hardware design and my tickled-pinkness over designing and fabricating my first PCBs, it only seems appropriate to follow it up with discussion of how the Propeller's capabilities were used for this project. I pulled some things off here that I can't really imagine being able to do with a single-core microcontroller.

To sum up, the problem statement for this project is: Take a text string, defined either by user input, or built in real time ...