Tuesday, July 9, 2013

Miniature MSP430 Programming Connector

The MSP430 is perfect for low-power and super miniature projects. Not only are smaller circuit boards cheaper to make, but they are desirable in many applications; such as in wireless sensor nodes, wearable electronics, and others. Standard 0.1" headers are simply too big for very small boards. To reduce the size requirement for the programming header, I have started using 0.05" headers. With this post, I would like to share how I use smaller headers to easily make my projects smaller and more cost efficient.

Due to how cheap the MSP430 LaunchPad is, it is often the best way to program your custom MSP430 boards. One of my earlier posts details how I use the LaunchPad to easily program custom boards using a 6 pin 0.1" header. It is important to me that I include both the UART RXD and TXD pins in the programming header for debugging purposes.

The simple schematic is shown above. Using a 3x2 pin 0.05" header on the target board, I created a "converter" board which connects to the LaunchPad using a 6 pin 0.1" header. Additionally, if I want to reduce the footprint further, I can use only a single 3x1 pin 0.05" header, ignoring the VCC, RXD, and TXD pins (as long as the target device is self powered).

The circuit board is shown above. It is very simple, yet very effective. The overall footprint of the programming header has been reduced significantly. Some possible improvements include the addition of a switch to allow you to choose if the device will be powered by the programmer or not, a protection diode for VCC, and a reset push button for those devices which are too small to have one. If you use the Eagle file provided below to make your own, please keep the URL to my blogs on the silkscreen.


For almost no cost at all, you now have a miniature MSP430 programming header that you can use on all of your future projects. This concludes my small but useful post.

Sunday, February 17, 2013

One Step Closer to the Iron Man Lab!

Ever since I saw Iron Man I have dreamed of having Tony Stark's personal lab. A newly discovered project via hackaday brings us one step closer!

hackeda.com allows you to generate an Eagle CAD schematic from basic circuit building blocks. While this interface is in its early stages and there is a lot of room for growth, I believe that this project can grow into an amazing tool that we can't live without.

I really hope we all get behind HackEDA, I really would like to see it prosper. Imagine a day where you can spend your time being creative, rather than painstakingly creating schematics for your ideas. One thing I would like to see from HackEDA however, is an open source computer application for the whole concept. While this might create some fragmentation (which many open source projects struggle with), I believe that this project could benefit from massive and rapid development.

Please keep an eye on HackEDA, I believe it is the future of circuit design.

Easy Peasy

Despite the fact that many newer parts are only available as surface mount components, it has never been easier to get a professionally looking electronics project completed. Eagle CAD is a free tool for designing very high quality circuit boards. Additionally, Eagle CAD has a multitude of libraries which can be imported and used in your project.

What about creating the actual circuit board? The days are gone where you have to fight with a blank circuit board, iron on traces, and a mini-drill press to get a low-cost circuit board. There are many places where you can order cheap custom circuit boards that are very high quality! Way nicer than anything the average person could make on their own.

OSH Park allows you to directly submit your Eagle CAD circuit layout and view a rendering of it online to ensure everything looks ok. Between 2-3 weeks later you have three copies of your circuit board for $5 per square inch. Another option for larger boards is Seedstudio's Fusion PCB Service.

Great, now we have a beautiful circuit board that we have no idea how to solder. Although devices can be very hard if impossible to solder, soldering surface mount devices has never been easier. The the coming months I will be writing blog posts on my newest setup at Hardware Breakout, finishing up my posts on a homemade toaster oven reflow oven in addition to posting instructions on how to build a cheap (<$150) PCB stencil laser cutter.

A quick peak at my small laser cutter.
It takes me no time at all to solder the smallest components with perfect accuracy  With the process streamlined so much, I can focus on building cooler and more complex projects. Stay tuned for these new posts!

Some Additional Library Tricks

For those of you who don't know, TI and other manufacturers such as Analog Devices have been using a new tool which brings CAD footprints of their parts to almost any CAD software. While companies like TI provide an Eagle Cad library for many of their parts, there always parts which are not included.

Let's run through the process quickly.

  1. Go to your part (for example, the PCM2706, a USB audio DAC from TI), hopefully there is a CAD/CAE Symbol section.
  2. On the side, TI provides a link for the Ultra Librarian software. Install this program, this is where the magic happens.
  3. Once installed, download the bxl file for the actual part and open it in Ultra Librarian.
  4. The GUI is fairly straight forward. It provides a quick view of the part and allows you to check off which CAD tools you use (e.g. Eagle CAD)
  5. If you selected Eagle CAD, Ultra Librarian outputs a script for adding the part to an Eagle Library.
  6. Open up your desired library in Eagle, run the script. There you go! The part has been added to your library.
While this process does not create the prettiest schematic symbols, it does work very well. I have used this for many chips and am very impressed that the manufactures finally are supporting a wide variety of tools via this program.

The Stark Lab

I imagine a day where the following steps are all that is needed to get a great piece of hardware made.

  1. "Computer, I want a circuit board that has a powerful MSP430 on it that is powered by two AAA batteries and includes a gyroscope, a 3-axis accelerometer, a micro-SD card, and a Bluetooth Low Energy radio.
  2. A few seconds later, my computer submits a perfect design to OSH Part without me having to double check it while it orders all the parts I need directly from Mouser or Digikey.
  3. Three weeks later my board arrives and I have all the parts ready and loaded into a homemade pick and place.
  4. All I have to do is hit go, and the laser cutter starts creating the stencil needed for the board
  5. Some kind of robotic arm/conveyor belt then applies the stencil and solder paste to the board and then deposits the it in the pick and place machine.
  6. Once all the parts are populated, the board automatically gets placed in my toaster oven reflow oven. A few minutes later, with about 5 minutes of my time all-in, I have a completed circuit board which I can now use in a new project.
While this may seem far off, it really is not as far off as you would think. I predict that in a few years, it will be possible to have a system like this for less than $500 all in. Not bad when you consider how much professional equipment which can do the same thing (albeit in mass) costs.

I personally do not believe that this will reduce the need for circuit knowledge and make us stupid. I believe that this will allow us to be more creative. There will always be a need for the low level skills, but there is no reason to spend all of your time on the low level stuff!