And that’s a wrap. Well, almost. I need to bump up the amplification on the headlights and decal the model, but other than that, it is finished! The entire point of the exercise was a proof of concept on an accurate modern emergency vehicle lightbar, and boy oh boy did I learn a lot along the way. I’ll list those things after the video.
As the prototype of what is sure to be many incarnations to come, I dub this ’07 Ford Shelby GT500 my ‘Demonstrator‘! Please ignore the 8xAA battery pack on the side. Normally, this car can be powered by a 9V that fits nicely into the engine compartment, but I was plumb out of 9V batteries. Yes, there’s some in the house smoke detectors, but Murphey’s Laws have taught me a thing or two, so I left those 9Vs where they were 🙂 Anyways, using a 8xAA power supply tested the circuitry against a 12V source, so it’s all good! Enjoy:
Demonstrator: 1:24 Model Whelen Liberty Police Lightbar from claymore1977 on Vimeo.
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.
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.
In between orders of Texas Instruments Launchpads evaluation boards from Mouser or Newark, don’t forget that TI has a free sample program that can get you a couple free MSP430 chips of varying models. Combine the raw chips with the ability to power and run MSP430’s off the red Launchpad board, and you can have quite the small army of animation and automation circtuis deployed on your layout in no time and very low cost!
Just please remember to keep TI interested in manufacturing the MSP430 processors by actually buying a few now and then. I think that if the hobby of model railroading can provide a significant enough demand for the MSP430 line of microprocessors, then we could help keep the prices low and increase the online support for the Launchpad based chips. Currently, there far more resources for the Arduino. Some of which can be ported to the Launchpad, some cannot.