Dropping a quick note here to show everyone that 1) I’m still alive and 2) What I’ve been messing with.
As seen in the picture, I’ve ordered some cheap 20 pin TSSOP/SOIC breakout boards and a few of the TSSOP-20 versions of the MSP430G2553. The boards measure 19mm by 27mm and I got them off ebay (Search for 20pin TSSOP Breakout). Big thing is to pay attention to the pin spacing. The MSP430G2 TSSOP pin spacing is 0.65mm, and that appears to be pretty common
Now, 19mm by 27mm is small enough to fit into a matchbox car (Hint towards a project I’m working on) and they can be filed down another 2-3mm in each direction. Since the SOIC footprint on the reverse side is a few mm wider than TSSOP, that’s pretty much as small as this breakout can get. A custom PCB or different breakout that only has the TSSOP mounting on it could be, theoretically, much smaller.
Anyways, while I’m still messing around with various on-board componentry, popping the chip out of the Launchpad redboard and using the board’s Vcc, GND, Test and Reset pins as the programmer for this TSSOP endeavor works like a champ. I encourage you to try it out. I was floored at how easy soldering TSSOP components was!! Flux the pad and the chip, gently clamp the chip in place, get a *small* dab of solder on your iron and swipe it across one row of pins. Repeat for other side, done.
Up next with TSSOP
I am very encouraged by this project as I believe I will be able to deploy MSP430G2 based projects into scales as small as HO, possibly even N. Next up for me is a custom PCB and power supply for these smaller form factor projects. I’m really having a blast with these projects!
I’ve been slowly chipping away at yet another additional side project. What’s that make, 18? 19? This one should have been prioritized higher, but I just never got around to it. Anyways, the whole aim of the LP4MRR community as envisioned by Terry Terrance was to put inexpensive, relatively easy to use, feature full electronics options into the hands of the average model railroader. Unfortunately, spread of the awesomeness that is the Launchpad has been somewhat slow due to the high learning curve of everything it takes to program and use a Launchpad.
A few months back, I asked myself the very dangerous question of: “So, what if….” More specifically, I asked, “So, what if I could find a way to get an average Joe Model Railroader the ability to upload a precompiled ‘sketch’ of code onto a Launchpad without Joe ever needing to use Code Composer Studio?”
There is so much left to experiment with concerning the Launchpads connectivity with JMRI that it’s mind boggling. One thing that has captivated quite a few of my brain cells recently is the notion of Virtual IO points.
The basic concept of IO points is relatively straightforward. A pin on the Launchpad is a single IO point. It’s either Input or Output. But the Launchpad is so much more powerful than just a bit setter or a bit reader! When thinking about such a waste of ‘power’ using the Launchpad as a 12 pin CMRI node, it hit me like a ton of bricks:
In my continuing research into CMRI Emulation on an MSP430G2553 chip, I recently tackled a few new challenges. Firstly, I wanted to expand the IO of the MSP430 via shift registers and control those pins from JMRI. Secondly, I wanted to address the issue of smoothly render a 16KHz PWM signal while simultaneously performing other tasks. To date, I have had success with PWM only when the MSP430 is performing just the PWM calcs and no other tasks. Previous attempts at using algorithm based PWM have resulted in jittery flashing on the LED being controlled by PWM while there are other items being processed by the MSP430.
The most recent sets of experiments have been a major success. Short video:
CMRI + 16KHz PWM Proof of Concept from claymore1977 on Vimeo.