Okay ladies and gents, here’s a Chasing Light project using a single Shift Register (74HC595) and a TI Launchpad. (I’m currently following a line of research using the Shift Registers, but there is an easier way to do this with just a Launchpad alone.) It can be easily adapted for many uses. Examples include, but not limited to:
- Theatre Signs
- Airport Landing Strip
- Eat At Dave’s Signs
This particular Launchpad project uses an external device called a Shift Register. Simply put, it’s a device that remembers the 1 or 0 you just put into. If you put another 1 or 0 into it, it shifts all the existing saved 1’s and 0’s over one slot and adds your newest value in. It can hold 8 values, hence the term 8-bits.
Here’s what it looks like when its all put together on a breadboard:
Chasing Lights v1.0 from claymore1977 on Vimeo.
As I have been working with the TI Launchpad and MSP430G2 series of microcontrollers, I have been slowly creating a set of macros and functions that make programming the Launchpad easier. The header file for this is available here, but I wanted to create a simple example of how and why it’s useful.
Drawing upon the example by TI about using a 74HC595 ShiftRegister, we see that in order to have the LEDs perform this pingpong effect:
Bit Shift Register on TI Launchpad from claymore1977 on Vimeo.
So it turns out there is a GG1 on display at the Harrisburg, PA Amtrak station. It is rather fortunate that I use this same station for going to and from work.
The GG1 is an odd looking loco, but something about it speaks ‘power’ to me. I am not sure that I would ever have one running around my layout, but there is something about railroad history that has me captivated. My current focus of research is the Southern Pacific, specifically the Arizona parts of the line. Even though the GG1 was really only over here on east coast lines, it is still awesome. Further, I get to see it daily!
The PRR GG1 was a class of electric locomotives built for the Pennsylvania Railroad for use in the northeastern United States. 139 GG1s were constructed by General Electric and the Pennsylvania’s Altoona Works from 1934 to 1943.
Entering service on the Pennsylvania in 1935, the GG1 also operated on successor railroads Penn Central, Conrail and Amtrak. The last GG1 was retired by New Jersey Transit in 1983; most were scrapped, but several are in museums in the US.
The lightbar project work continues! All the proper ohm value SMD resistors *finally* arrived in the mail, and a few short evening work sessions later, the resistors are in place, dud LED light modules replaced and leads carefully soldered in… we have an operational Lightbar!
Now, the front 3 Red and 3 Blue are electrically different than the rear 3 Red and 3 Blue, so add in the working center takedown and 2 alley lights, there are 15 independent LED modules on this bar. However, the software that was on the MSP430 I hooked them up to only was written for the front 3 Red and 3 Blue only, so the bar is not flashing at its full potential…. yet!
Here’s a short video that’s a bit out of focus. I didn’t catch the focus issue when I uploaded it because it was well past midnight 🙂 Once I update the software I’ll film a higher quality version.
1:24 Model Whelen Liberty Police Lightbar from claymore1977 on Vimeo.
Work on the 1:24 Whelen Liberty Lightbar continues. My order of 0805 SMD resistors I ordered from Garrett Electronics Corporation via Amazon.com arrived in the mail yesterday, so I was able to mount them onto the lightbar. Goodness me those things are small! I’ve got to find some better techniques at soldering if I want to ever tackle a project using 0603 LEDs/resistors….
My apologies for the dark pictures, but I haven’t figured out a good lighting solution yet and the iPhone camera really works best with a lot of light.
Here is a shot of them mounted on the underside of the light bar. The lightbar itself is only 50mm wide, 10mm deep and 4mm tall. Talk about a pain to solder in place!