New Devices!

If you haven't already seen from some of the other websites in the LaunchPad community, TI is gearing up to release more MSP430 devices that are compatible with the LaunchPad.  Some of these will be 20-pin chips, and will make use of the entire board.  You can see details of the new devices on TI's website.

In regards to the new devices, some will include more of the MSP430 peripherals, most notably a hardware UART for serial communication.  The UART uses the same two pins that TI chose to use on the LaunchPad for the timer-based UART used in the demo program that comes with the G2231 chip.  Unfortunately, it swaps the transmit and receive functions on these pins.  TI is working on potentially re-designing the LaunchPad, and has asked for the community's views on how to approach this issue.  If you haven't already, go to the post on the E2E Community site, review the proposals they've given, and vote for the solution you think is best!

Tutorial 12: Making Comparisons

As we've seen, microcontrollers have great usefulness in digital electronics. In the real world, and for scientific applications, however, digital is not always adequate. In this tutorial, we begin working with analog signals using a 1 bit analog to digital converter: the comparator.

Some MSP430 devices have a built-in comparator (called the Comparator_A+ module in the technical documentation, I'll refer to it as CA+ here), including the MSP430G2211 that comes with the LaunchPad kit. (See TI's website for other LaunchPad-compatible devices that include the CA+ module.) Up to this point, all of the tutorials could be used on both the G2211 and the G2231 chips in the LaunchPad kit by changing the #include header appropriately. For this tutorial, you will need to use the G2211.

Overview of the Comparator_A+ Module

Simplified diagram of the Comparator_A+ module.  Taken from the book
MSP430 Microcontroller Basics; I highly recommend getting a copy of this book!

The CA+ module is very flexible, allowing multiple GIO pins to be connected to its inputs and including a variety of useful internal voltage references. As you may recall, a comparator has two inputs, called inverting and non-inverting (often labeled V+ and V- respectively). The V+ input can be connected to three different pins for external signals, or any of three different internal reference signals. The V- input can be connected to seven different pins (two overlap with the V+ inputs) and any of the internal references. CA+ has an output that can be read in software, trigger the CA+ interrupt, and trigger a timer interrupt. All of these options give the CA+ module its flexibility and usefulness to us in developing instrumentation.

Take a look at the datasheet for the G2211, and find the page that shows the pinout diagram for the chip. The pins that can be connected to the CA+ inputs are labeled as CAx. Note that CA0-2 can be connected to V+, while CA1-7 can be connected to V-. Note also that in addition to providing the CA7 input, P1.7 can be configured to provide the output value CAOUT externally.

Configuring the Comparator_A+ module

The CA+ module has three different registers for its configuration: CACTL1, CACTL2, and CAPD. These registers are described on pages 19-10 to 19-13 of the x2xx Family Guide. We'll look at the basic pieces here.

CACTL1

• The CAREFx and CARSEL bits (4-5 and 6) control the internal references for the comparator. Bits 4 and 5 select the reference value, while bit 6 selects which input is connected to the reference. There are three references provided in the module. Two of them are a fractional value of the voltage powering the MSP430: 1/2 Vcc and 1/4 Vcc. If you are powered from the USB (3.6 V), these references are 1.8 V and 0.9 V respectively. (These are accurate to about 1%.) A third reference is provided by the forward voltage of a transistor. This voltage is typically 0.55 V, but is less accurate and susceptible to temperature changes.
• The CAIFG, CAIE, and CAIES bits (0-2) control the interrupt for the comparator. Bit 0 is the interrupt flag, which clears automatically when the interrupt is serviced. Bit 1 turns on the interrupt, and bit 2 selects whether an interrupt is triggered on a rising edge (low to high transition) or a falling edge (high to low transition).
• The CAON bit (3) turns the comparator on when set, and off when cleared.
• The CAEX bit (7) is used to exchange the two inputs; ie. the pins/references connected to V+ and V- are swapped. (In addition, the output is inverted to compensate for the change.) This ability is useful in examining values close together, but for basic functionality is not necessary.

CACTL2

• The P2CAx bits (2-6) are used to select the pins connected to the comparator inputs. V+ is selected with P2CA0 and P2CA4. V- is selected with P2CA1-P2CA3. The x2xx Family Guide provides a table on page 19-12 that explains which bit configuration selects the various pins.
• The CAF bit (1) puts the output through an RC filter to smooth out any rapid oscillations that might occur if the comparator inputs are very close together. It's not always necessary, but is a good idea to enable if you're using slowly-varying signals.
• The CAOUT bit (0) is the output value only; you cannot write to this bit, but reading it will give you the current value of the comparator output.
• The CASHORT bit (7) shorts the two comparator inputs together. While this might sound like an odd thing to do, it is useful under certain circumstances. Basic use of CA+ will not use this function.

CAPD

• The CAPD register is analogous to the Port registers; each bit corresponds to the input pins CA0-CA7. The purpose of this register is to disconnect the digital circuitry for the GIO ports from the pins that are being used with analog signals. If an analog signal close to the transition voltage for the digital circuit is applied to the pin, the digital portion could oscillate between high and low fairly rapidly. This effect can cause degradation of the circuitry in the chip, and so it's best to disconnect it completely when analog signals are used. In fact, when a pin is connected to the comparator, it is automatically disconnected. The purpose of this register is to manually control the disconnect. Sometimes you may want to use the comparator on multiple signals; only one pin can be connected to the comparator at a time, but you can switch the input connection in the software. While the CAPD method of disconnecting the digital circuit is redundant when only one pin is used, enabling the CAPD bit for a pin connected to an analog signal prevents it from being reconnected to the digital circuit when the software causes the comparator to switch input pins.

Programming Example

To demonstrate the CA+ module, look at a basic comparison program in bcompG221.c. The idea in this program is to measure an analog voltage, and flash an LED if the voltage is above a particular reference, in this case 1/2 Vcc (1.8 V when running off the USB power). To do this, the program uses the Timer_A module to flash the LED, while the Comparator_A+ uses an interrupt to turn the flashing on and off.

The portion of the code that configures the CA+ module is as follows:

CACTL1 = CAREF1 + CARSEL + CAIE; // 0.5 Vcc ref on - pin, enable
                                 // interrupts on rising edge.

CACTL2 = P2CA4 + CAF;      // Input CA1 on + pin, filter output.

CAPD = AIN1; // disable digital I/O on P1.1 (technically

// this step is redundant)

The values used here can be found in the header file for the G2211. Setting CAREF1 alone selects 1/2 Vcc as the reference voltage and setting CARSEL connects the reference to the V- input. Setting P2CA4 alone selects CA1 (same pin as P1.1 for the G2211) as the V+ input. AIN1 was defined to be BIT1, so we permanently disable the digital circuit on P1.1 for this program. This step wasn't essential, since we don't change the inputs on the comparator in this program.

After all the peripherals are configured, the comparator is turned on with CACTL1 |= CAON (the |= operator is used to prevent changing any of the other configurations we put in at first) and the chip enters LPM0.

TimerA periodically triggers an interrupt and toggles the P1.0 output with the value stored in flash. When CAOUT is 0, flash is 0 and so the LED never turns on. When CAOUT is 1, however, flash is set to LED1 (defined to be BIT0) and the LED toggles on and off.

Now let's look at the Interrupt Service Routine for CA+:

#pragma vector = COMPARATORA_VECTOR

__interrupt void COMPA_ISR(void) {

if ((CACTL2 & CAOUT)==0x01) {

CACTL1 |= CAIES;    // value high, so watch for

                    // falling edge

flash = LED1;       // let LED flash

}

else {

CACTL1 &= ~CAIES;   // value low, so watch for

                    // rising edge

flash = 0;          // turn LED off

P1OUT = 0;

}

} // COMPA_ISR

None of the examples that TI provides on their website demonstrate how to use the Comparator_A+ interrupt. To find the proper syntax, I located the vector name in the msp430g221.h header file. (Remember, the vector name must be what the compiler expects (in this case, COMPARATORA_VECTOR). The header file is the safest place to locate the proper name.) The interrupt routine name, of course, can be named anything. Something descriptive is always helpful, though. For this program, I chose COMPA_ISR(). The service routine first examines the value of CAOUT. If it is 1, then the voltage on V+ is higher than the reference on V-. The next interrupt should be when the value drops below the reference again, so it sets the edge select to a falling edge. It then sets flash to a non-zero value so the LED will blink. If CAOUT is 0, then V+ is lower than the reference. The edge select is set to a rising edge, flash is set to zero so the LED won't blink, and the P1OUT is cleared to ensure the LED is off.

To test the program, you can connect a potentiometer (anything above 1 kΩ should work) between Vcc and ground, and connect the wiper to the P1.1 pin on the LaunchPad. Adjust the potentiometer to see the LED start blinking (indicating the voltage on the pin is above 1.8 V) and back again to see it turn off (indicating the voltage is below 1.8 V). If you don't have a potentiometer, you can try two resistors of different values. Connect one resistor between Vcc and P1.1, and the other between P1.1 and ground. If the smaller resistor is between Vcc and P1.1, the voltage should be more than 1/2 Vcc, and the LED blinks. If the larger is in that place, the voltage is less than 1/2 Vcc, and the LED turns off.  (Caution: If you use two resistors to try this, be wary of removing the resistors while the LaunchPad is powered.  You might not do any damage, but it's safer to power off a circuit before pulling pieces out.)

Reader Exercise: Change the program so that the LED doesn't blink, but is set on/off constantly for high/low values of CAOUT. Then use TimerA to periodically change the reference voltage between 1/2 Vcc and 1/4 Vcc. When comparing to 1/2 Vcc, it should turn the red LED on P1.0 on if the analog signal is above the reference. When comparing to 1/4 Vcc, it should turn the green LED on P1.6 on if the signal is above the reference. Turning the knob on the potentiometer, you should see the green LED light when the signal is above 1/4 Vcc, then the red LED light when above 1/2 Vcc.

New Tutorials Coming Soon

I just wanted to put a quick post up letting people know that more tutorials are on their way.  I've been in Norway for the past long while doing my research for my Ph.D.  We launched our sounding rocket today, and I will be coming home in a few days.  At that point, I can get my hands on some hardware to do the tutorial I've been anxiously planning.  Should be a lot of fun; hope you're looking forward to it!

This post written from Longyearbyen, Svalbard; 78 degrees, 13 minutes North latitude!

Design Note: Op-Amps

This quick note is less for design in an MSP430 circuit, but a quick tutorial on Op-Amps that will help those less familiar with electronic components to understand the next tutorial.

The Operational Amplifier, or Op-Amp is an extremely useful piece of hardware. (Some MSP430 devices come with Op-Amp peripherals built in!) The name reflects two very important functions of the device; it can be used to effect the equivalent of a mathematical operation to one or more electrical signals, or it can be used to amplify a signal.

While the details of how an op-amp works physically are a little complicated, visualizing what happens from a practical viewpoint is not so difficult. There are two inputs, labeled V+ and V- in the above schematic. The + and - labels next to the V+ and V- pins help you remember which pin is which. While both are inputs, they don't necessarily behave the same way, which gives the op-amp some of its flexibility. There is one output (Vout). Vs+ and Vs- are the positive and negative sides of a power supply. (Note that Vs- does not necessarily have to be a negative value--some circuit designs use ground on this pin.)

When you analyze an op-amp design, the simplest way to view the chip is to recognize that the output will be an amplification of the potential difference between the V+ and V- pins. Usually the gain on an op-amp is very high (1-10s of thousands) and so a very small difference can be enough to drive the output all the way up to Vs+ (if V+ > V-) or down to Vs- (if V+ < V-). (This is the behavior of what's called a differential amplifier.)

Since the gain is so high, we can use the op-amp in this configuration to compare two voltages. If voltage 1 on V+ is greater than voltage 2 on V-, we get a high output from the op-amp. If we have the reverse situation, we get a low output from the op-amp. In reality, general purpose op-amps are not the best choices to make this comparison, so a special chip called a comparator was designed to do this job. We'll examine it more closely in the coming tutorial.

The true power of the op-amp comes in the ability to tie the output to one of the inputs, providing a feedback that drives the output one direction or another. With feedback in place, the output will change until one of three conditions is reached: the output has increased to Vs+ and cannot increase further, the output has decreased to Vs- and cannot decrease further, or the output has found a state where the two inputs are the same potential. Whenever feedback is used, the output will drive up or down seeking to make the potential difference on the inputs zero.

Op-amps are a very important component for electronic designs. If you're not familiar with them, I'd highly recommend doing some reading to understand them better. (See for example the page on Wikipedia.) My purpose in this note was to mention the comparison operation so that readers have at least been introduced to the comparator before I write up the next tutorial.

This post was prepared while in Andenes, Norway.

Design Note: Power

A number of comments in the community lately have suggested a note on powering the MSP430 outside of the launchpad would be helpful; to that end I'm writing up this design note to help explain the options and requirements for powering the MSP device.

Chip Configuration

The MSP430 has two pins for power that correspond to the high and low states for the digital logic: Vcc and Vss respectively. For the MSP430, Vss is typically ground and Vcc is usually in the 1.5-3.6 V range, depending on the application. (On the value line devices, these are labeled as DVCC and DVSS, with the D referring to the digital circuitry. Some devices also have a separate AVCC and AVSS for analog signals and peripherals. On these devices, you can tie the A and D supply pins to each other, but the ability to use separate supplies is there.)

Regardless of your chosen power source, there is one thing that must absolutely be done in all designs. Every MSP430 device has a RST/NMI pin. This pin allows you to reset the chip externally by grounding that pin. (The non-maskable interrupt feature is something we'll look at in a more advanced tutorial sometime in the future; for now, only the default operation of the pin is considered.) The LaunchPad is designed with a button that does just that.

In the button tutorial that for a button to behave as an input, the pin needs a definite default state (either grounded for active-high buttons or Vcc for active-low buttons). In order for a chip to be powered, the RST pin must be tied to Vcc. Note that a direct wire is not a safe method of doing this; if a reset is triggered and the pin is grounded, it would short out your power supply. A pull-up resistor is required, and a careful look at the LaunchPad schematic (it's on page 15) shows that TI uses a 47 kΩ resistor, and that seems a reasonable choice for the typical supply voltages one would use for any MSP430 design.

Note in the schematic one other aspect: on the Vcc pin, there are two capacitors. One of these is a 0.1 μF capacitor (100 nF if you're unfamiliar with SI prefixes) and the other a 10 μF capacitor. These capacitors are used to filter the power input, by which we mean keep any fluctuations in the power supply from affecting the value of Vcc. You will see below that many suggested designs for regulated power supplies use a 10 μF capacitor or similar on their output, and you may be able to get away with not using another on the MSP430 if you use one of these power sources. (You might have also noticed a small 1 nF capacitor connecting RST to ground. While not absolutely necessary, if you find your design has sporadic resets that you can't explain, add this capacitor. A TI support technician tells me that for SBW programming to work properly, it should be a capacitor of about 1 nF in size.)

Unlike the larger filtering capacitor, the 0.1 μF should always be included unless you have good reason not to. Digital circuits, especially when run at higher frequencies, can be susceptible to noise from pins switching between high and low. This capacitor is used specifically to filter out that noise, and works best if it can be physically located close to the Vcc pin on the MSP430. If you plan on making your own board designs rather than relying solely on the LaunchPad, get a number of this size of capacitor, as it will be used a lot!

Power Options

There are a huge number of possibilities for powering your circuit: solar panels, large super-capacitors, even various fruits will supply enough electrical power to run your MSP430 designs! For most hobbiest work, however, there are three major places from which to draw power: batteries (consumer type, like you'd buy at the grocery store), the wall AC, and the USB port of a computer.

Batteries are sometimes the easiest choice, but there are some caveats to consider. For the most part, a typical battery holder with a couple of wires can be connected to Vcc and Vss. On the LaunchPad, there are pins for this purpose; soldering female header pins to the wires or using jumpers make battery use simple. Before just connecting up, however, remember that the MSP430 can't handle voltages higher than about 4 V. A 9V battery might sound like a good idea, but alone is not safe to use on the microcontroller.

Good combinations of batteries: 1 or 2 alkaline AAA, AA, C, or D cells would give 1.5 V or 3 V, both good supply voltage values. If you switch to a rechargeable battery, double check the type. Many rechargeable cells are nominally 1.2 V rather than 1.5 V. If you use the 1.2 V cell types, you can use up to three of these in series (a total of 3.6 V) without trouble. Coin cell batteries also work well if you have a holder for them. In general, batteries need no other external parts, though it may be a good idea to have both filtering capacitors on the MSP430 in this case.

If you use a higher voltage battery or battery combination, or if you want to use the USB power (5 V), you will need to step down the voltage to an acceptable level. While there are a number of ways to do this, perhaps the simplest and most effective is to use a voltage regulator. (The LaunchPad is powered from USB; the portion of the board dedicated to the SBW programmer includes a voltage regulator to drop the USB line voltage to 3.6 V.) These components are cheap, robust, and work very well when used properly. Some can even handle such a wide range of inputs that you could connect most any common power source to it and have the output you need. If you've never used a voltage regulator before, read up about it and learn how to use them. An excellent tutorial can be found at SparkFun, and is a good place to start. For my designs, I like to use Linear Technologies regulators, such as the LT1763. (Note that the suggested design on the LT1763 page includes a 10 μF capacitor on its output.) This particular regulator is only available in surface mount packages, but Linear makes a number of other varieties that are comparable in through-hole packages (as an example, the LT1965). There are plenty of options out there that fall into the voltage ranges useful for the MSP430.

If you want to use a wall outlet, you will also need a transformer with a rectifier. Plenty of stores carry such power supplies in a variety of voltages. Anything in the 1.5-3.6 V range will work directly, but I've found most wall-wart supplies are 5 V or higher, and will require a regulator to operate the MSP430.

There are many, many more ways to power your circuit, but these will give you a few reliable sources to start from. Remember to tie the RST pin to Vcc with a resistor, add a 0.1 μF capacitor near the Vcc pin, and keep your voltage within the usable range for the MSP430. Don't forget to connect ground (or the negative side of the battery as the case may be) to the Vss pin, and have fun exploring your power options!

Tutorial 11-b: Using the Auxiliary Clock

If you did the exercise at the end of the last tutorial, you probably noticed that the program stopped working if you tried using any of the LPMs other than LPM0 or LPM1.  The reason for this has to do with the clock that is chosen to power the timer.  So let's take a careful look at just what's happening in the limboG2211.c program.

First of all, we set the DCO to the calibrated 1 MHz frequency.  Pretty straight-forward here; the MSP430 MCLK timing the CPU will operate at very close to 1 MHz.  What isn't as obvious is that the sub-main clock (SMCLK) is also driven by the DCO, and so also operates at 1 MHz.

The timer is then configured to run with the SMCLK divided by 8, or at 125 kHz.  The timer counts to TACCR0 and then triggers an interrupt, wherein the current through the speaker (or current to the LEDs if you changed it to that mode) is switched.  The frequency of the switching drives the speaker to create a particular tone.

In between switches, the MSP430 enters LPM0.  We can see what happens to the chip when entering this mode by looking again at the diagram and table on page 2-15 of the x2xx Family Guide: the CPUOFF bit in the Status Register is set to 1.  The CPU turns off, as does MCLK, leaving SMCLK and ACLK running.  If we run LPM1, then the CPUOFF bit is set as in LPM0, and in addition SCG0 is set to 1.  We can see that this mode has the added benefit of turning off the DCO if the SMCLK is not being used.  In our case, we're using SMCLK to drive Timer A, so the DCO is not turned off for LPM1.  Essentially, for this program, there is no difference between LPMs 0 and 1.

If we move to LPM2, however, we set CPUOFF and SCG1, which has a much different effect: in addition to the CPU and MCLK, SMCLK is disabled, allowing the DCO to also be disabled.  In our program, then, when we enter LPM2 we turn off the clock driving Timer A; Timer A never reaches TACCR0, and an interrupt is never triggered to cause the MSP430 to exit the LPM.  In LPM2, however, ACLK is allowed to continue running.  If we drive Timer A with ACLK, then, we could use deeper modes and consume less power overall!  Less power means more battery life and more efficient use of the resources in the MSP430 design.

ACLK is typically driven at low frequencies (comparatively), and so draws less power than does DCO, further improving our goal of reducing power consumption.  By default, it is set to use a 32,768 Hz quartz crystal.  Your LaunchPad kit came with a crystal that you can solder onto the board to use here.  Alternatively, you can configure the LFXT1 clock source to run from an internal oscillator, similar to the DCO, that operates at a very low frequency (typically 12 kHz).  This oscillator is referred to simply as the VLO.

Configuring LFXT1 and ACLK
If you're planning to use the crystal oscillator on LFXT1, there's likely little that needs to be done.  The crystal that comes with the LaunchPad needs 12.5 pF capacitors for stability, and you might notice the SMD solder pads near the crystal location for capacitors.  You can use discrete capacitors if you like, but the MSP430 is also configured with a few capacitances internally, and 12.5 pF is one of the choices.  Using the crystal is a simple matter of soldering it onto the board and configuring the BCS+ module correctly.  There are a lot of switches and controls involved here, so we'll save crystal control for a later tutorial, and assume for now that we're going to use the VLO to source the Auxiliary Clock.

Section 5.3 in the x2xx Family Guide (starting on page 5-13) holds the necessary information for configuring the BCS+ module.  The registers we need for now are BCSCTL1 and BCSCTL3.  In terms of setting up the VLO, we need the XTS bit in BCSCTL1 (bit 6) and the LFXT1Sx bits in BCSCTL3 (bits 5 and 4).  The XTS bit sets the LFXT1 clock source to low or high frequency.  Many MSP430s in the x2xx family let you use a high frequency crystal for this source; the value line devices, however, only support low frequency (ie. 32,768 Hz) crystals.  When this bit is cleared to 0 we have configured the chip for low frequency ranges.  Some devices, including the value line chips that come with the LaunchPad, allow us to use the VLO.  This mode is selected by setting the LFXT1Sx bits to 0b10, as described on page 5-16.  To do this in C, we again make use of a header file definition:

BCSCTL3 |= LFXT1S1;  // sets LFXT1Sx to 0b10, VLO mode

We don't need to explicitly change the XTS bit, as it defaults to the low frequency setting.  This line is sufficient for setting up the VLO.

With LFXT1 now oscillating at 12 kHz, ACLK can be used for the peripherals.  You may recall from Tutorial 08-a that ACLK only sources from LFXT1, using either a crystal or the VLO.  We can, however, alter the frequency for ACLK by dividing the VLO by 2, 4, or 8.  This is done in BCSCTL1 with the DIVAx bits (5 and 4) with the configurations given on page 5-14.  For our purposes, we'll set ACLK to run at about 3 kHz by dividing the VLO by 4.  We do this with the following code:

BCSCTL1 |= DIVA_2;  // ACLK divide by 4

Keep in mind that you can also divide the clock in the peripheral itself, or further divide inside the peripheral.  For example, we can run Timer A at 750 Hz by dividing by an additional factor of 4:

TACTL = TASSEL_1 + ID_2 + MC_1 + TACLR;  // use ACLK, div 4, up mode, clear

To summarize, we can modify the limboG2211.c code to use the following:

BCSCTL1 = CALBC1_1MHZ; // Running at 1 MHz
DCOCTL = CALDCO_1MHZ;
BCSCTL3 |= LFXT1S1;     // VLO mode


TACCR0 = 14;  // With the Timer using ACLK (12 kHz), this
  // value gives a frequency of 12000/(TACCR0+1) Hz.
  // For TACCR0 = 14, that's 800 Hz.

TACCTL0 = CCIE;         // Enable interrupts for CCR0.
TACTL = TASSEL_1 + MC_1 + TACLR;  // ACLK, up mode, clear timer.

_BIS_SR(LPM3_bits + GIE);  // Enter LPM3 and enable interrupts

This code sets ACLK to run from the VLO (at ~12 kHz) and then uses Timer A to switch the speaker at ~800 Hz.  Most importantly, since we are now sourcing the timer which causes interrupts from ACLK, we can use LPM2 and 3 in our program.  Note that LPM4 would turn off the ACLK; using LPM4 is only feasible if we have some external interrupt source, such as watching for a signal on one of the GIO pins.

We'll return to looking at the low power modes soon; the first real scientific project we'll do will analyze and compare the power consumption of a simple MSP430 design using the various LPM settings.  To do this, however, we're going to need to measure an analog signal and record data.  The next tutorial will start us in this direction by looking at analog to digital conversion.

Reader Exercise:  Suppose your LaunchPad has the crystal soldered onto it, and is being used in a project that does not use ACLK at all.  The crystal will continue to oscillate, and use power (albeit a very small amount) that is not contributing to the overall design.  Note that none of the standard LPMs disable ACLK and the crystal oscillator except LPM4.  Write up the needed line(s) of code that would create a new LPM that keeps MCLK, SMCLK, and the DCO running, but disables ACLK and the crystal oscillator.

Yes, the blog is officially back!

Thanks, everyone, for your patience.  My research has been moving quite a bit lately and occupied the majority of my time.  Fortunately the 16 hour work-days are over, and I have some spare time and motivation to play with the LaunchPad some more.  I've posted the first part of a multi-part tutorial on Low Power Modes (by popular demand!) and have a bunch of great ideas coming up.  We'll be working toward being able to make your own LaunchPad circuit board (minus the SBW programmer, of course) and communicating with a computer among many other fun things.  Send me a note if you have any particular topics you're aching to learn about.  We'll keep on with LPMs and start ADC soon as I wait for the boards I've designed to arrive.  Watch for some design notes and other posts to come soon!