Hardware

TI makes a large variety of types and packages for the MSP430, from a basic, 14-pin PDIP to a 113-pin BGA Microstar. Selecting the right MCU depends on a number of factors, including the number and types of peripherals and devices that need to be controlled.

For the initial experiments, we'll use the MSP430F2132 and the 20/28 pin target board produced by TI.  These can all be purchased in a single package, and can include the MSP-FET430UIF flash emulation tool for programming the MCU.  This target board works with the x21x1 20-pin TSSOP variations and the x21x2 28-pin TSSOP variations.  The package comes with 2 F2132's, which are the largest of the chips usable in this board.  The x21x2 is useful for basic projects as it includes most of what could be needed, including an analog to digital converter.  Nearly everything done at this site will be doable on nearly any of the MSP430's, however.  Sometimes a small chip (even the new and inexpensive G-series types) will be sufficient, and some of the larger chips (with more pins) may be helpful in future projects.

The F2132 features:

• 16 MHz clock (at full voltage)
• 8 kb flash memory
• 512 b RAM
• 24 General Purpose Input/Outputs
• 10-bit SAR A/D Converter
• Universal Serial Communication Interface (communicates via UART, LIN, IrDA, I²C, or SPI)

The target board is a useful format for testing without needing to create a custom PCB or solder the MCU to anything.  It includes a socket designed to hold the TSSOP package.  Included are header pins (male and female) to attach on either side of the socket as seen in the photo above.  I've chosen to use the female pins, which allows me to connect wires to devices easily.  It also provides some protection from an accidental short from a stray wire bridging two pins that the male pins would not provide.  The general rule of thumb in rockets is that anything that is powered when disconnected (intentionally or accidentally) should be female, and that's the convention used here.

Also on the board is a place to connect a 32.678 kHz crystal for timing.  The MCU has excellent timers internally, so the crystal is not always essential; it's good to have for time critical applications, though.  The kit includes a 12.5 pF surface mount crystal, though one flaw in the board design is that there is no convenient way to ground the crystal case.  One option might be to solder a wire to the case and fit into the via that connects to ground.  The crystal included in my kit actually broke off of its fine leads when I was playing around with figuring out how to attach it, so I have not put a crystal on my target board yet.  Plated through hole form factors may be usable since the mounting place for the crystal on the target board is PTH.  A quick note about the capacitance of crystals--it seems the MSP430, or at least newer versions of it, are able to set the load capacitance internally via software, so other capacitances may be used; I'll use 12.5 pF since that's what came with the kit initially.

In addition to the F2132, some experiments will make use of the MSP430F5438 and the Experimenter Board made by TI.  The F5438 is the chip being used in my research, and so this combination gives me a way to program that particular chip while also providing an environment with lots of external devices and controls to use in experiments, including an LCD, accelerometer, and various interface devices.

Both boards can be powered by the FET or externally.  A future post will look into various options for powering an MSP430 project, and many experiments will simply use a pair of alkaline AA batteries (3.0 V).  Note that two AA's do not provide sufficient voltage for the processor to run at the full 16 MHz.

The equipment described here will not necessarily be appropriate for everyone, but are a convenient and useful place for me to start.  As I stated earlier, the ideas approached here will be useful for other projects using different chips and boards as well.  Next time we'll take a look at the software needed and start loading a simple program onto the chip.