Texas Instruments MSP430 LaunchPad.

To that end, I did two things. First, I bought ten MSP430 LaunchPads. These things are really inexpensive, so they make great stocking-stuffers. If you don’t know what the MSP430 is already (really, we talk about it constantly, where have you been), it’s a 16-bit microcontroller with really low-power consumption needs. They run on 1.8 to 3.6v power supplies at up to 16MHz, making them quite a powerful little beast for only $4.30, which includes the chip programmer. If you were to buy the chips alone, they cost about $0.50 each, with a few different serial communication protocols built in, and requiring only a small selection of external parts (2 resistors and 2 caps if you want to do it right, 1 resistor if you’re living dangerously, and face it, at $0.50, you can afford to live dangerously). It’s something of a long-term project plan of mine to buy 100 of these and try to build a small, physical neural network computer.

A lot of people have shied away from the MSP430 because the Code Composer Studio software–based on the professional-grade Eclipse development environment–is very difficult to use in comparison to the Processing-based software typically used to program Arduinos. But luckily, someone has taken the Arduino cue and created Energia, a Processing-based editor for use with TI’s LaunchPad line of MCUs! If you’re experienced with Arduino, using Energia is a snap, and if you’re not experienced at all, it’s really not that big of a learning curve.

I prefer to call it Serious Putty

Second, I bought supplies to make “magnetic Silly Putty”. About a week ago, I saw this Instructable about kneading some Iron-Oxide powder into a little Silly Putty and jumped on Amazon right away to get a 6-pack of Silly Putty eggs and a 5 lbs bag of black Iron-Oxide pigment. Honstely, 5-lbs is way too much, but there are plenty of other things you can do with it, like make ferrofluids or your own paint, so it’s handy to have around. You will need a fairly strong neodymium magnet, but again, these things are fun enough to have around anyway, so have at it!

Making the putty is really easy. I pooled all 6 eggs of putty together in a non-stick pan. On very low heat, I warmed up the putty until it was just too hot to handle with my bare hands. If it starts to become the consistency of chewing gum and sticks to the pan, don’t worry, it will unstick when it cools down. Don’t heat it further than that though, it will start to smoke and burn. Wearing rubber gloves to give me just enough insulation from the heat and to keep my hands from getting stained black, it’s just a matter of working a large, heaping tablespoon-full of the black powder into the putty. You will need to work the putty like taffy, stretching it and folding it to blend the powder evenly into it. Once the powder is sufficiently kneaded in to the putty, it will not stain anything, so keep testing it on the back of your rubber glove to see if it leaves any marks. I then cut the putty into 6 equal chunks and shoved them back in their eggs. It took 10 minutes total. I thought about taking some photos of the process to show it off, but really, it could not be simpler.

I’m hoping these gifts will be completely unexpected and will inspire people to try something they never would have considered on their own. The MSP430s are just a really easy, cheap, fun way to get into programming, and the magnetic Silly Putty is a great example of something you can’t buy as a product that is also extremely easy to make.

Tuesday – DIY Music Night

Wednesday – Open House

Thursday – Game Night Featuring Tetris Arm Wrestling Tournament

Friday – PTW Gala demonstration (offsite)

Events at Hive76 Monday through Thursday start at 7pm and 

ARE OPEN TO THE PUBLIC.

Friday Gala Ticketing information available here.

Back-lit view of paper and foil micro-controller board

After visiting The Hacktory’s “Soft Circuit” event, PJ and I were inspired to take a stab at making some micro-controller circuits using alternative, “high/low tech” approaches.  PJ made an MCU circuit using conductive paint (has potential, but needs some tweaks).  I opted to try a circuit board using metal leaf.  That happened to work on the first shot — although careful scrutiny of the picture on the left suggests there was some luck involved (there are holes in the circuit that come dangerously close to wrecking it).

Looks good from this angle and all the connections check -- you'd never guess it was hanging by a thread ...

I had considered using scored foil as a way to make free-hand, one-off circuit boards for quite some time — but until recently, I never had the mix of free time and raw nerve to actually try it.  It turns out that my reservations were probably well-founded, but it also happens that the technique is workable, and the results are actually aesthetically interesting.

We decided to make the board in a hexagonal shape (Hive76 — hexagon — get it?). First, we prepped circuit board material by spraying adhesive on card-stock and then sticking the faux gold-leaf on the prepared surface (this sounds simple, but the foil is maddening stuff, so the process involved profanity and a certain amount of despair).  Then we cut the foiled card-stock into hexagons. After that, we cut out a rectangle where the IC was going to go, so that there were no conductive paths under the chip.  Once the board was roughly prepped, we made a “squashed bug” of the IC , splayed its pins out, and soldered it to the gilded surface.  Using the gaps between the pins as a guide for an exacto knife, we cut free-hand traces that routed the pins of the chip to large zones on the edge of the hexagon (I was a little surprised that the cuts were free of bridges). Finally, we soldered a capacitor between the MCU’s Vcc and ground and soldered a 47k resistor between Vcc and the MCU’s reset line.  At that point, we had a working circuit that was in-system programmable — at least in theory.

Unfortunately, I had no idea how we might program the MCU or hook it up to external circuitry without damaging the fragile structure.  PJ came up with the idea that made it all workable … magnets.  All really good magic is done with magnets.  The idea here was to place the paper computer on a steel surface, which allowed us to stick magnets wherever we wanted to make a connection.  With steel under the circuit, the down-force of the magnets gave us firm-but-gentle electrical contact with the delicate foil. Once the magnets were in place, we only needed to touch alligator clips to them — since the clips were steel, they stuck happily. With the clips secured to selected points on the MCU, we were free to connect the opposite ends of the clips to the various external items needed for the circuit.  Note the ingenious use of paper-clips.  PJ again — see a pattern here?

Our first connection was power (two magnet connections, one for +3.6 volts, the other for ground).  Then we hooked up the Spy-bi-wire programming interface (two wires, two more magnets).  After that, we wrote the obligatory “blink LED” program and loaded it into the paper computer.  Naturally, we wanted to see the results — two more connections for the LED terminals and — Voila!  Here’s the movie …

Although motor control is potentially a vast and complex topic, with highly specialized branches, the basics are fairly easy to learn — and they’ll take you pretty far.   So … we’ll be prepared to present the following items:

• DC motors
• H-bridge circuits — these let puny microcontrollers run fairly powerful motors
• Stepper motors — just a little more complex to program than DC motors and they use H-bridge circuits too
• Quadrature Encoders — these are a  simple and accurate way to read the position of something

We’ll also try to discuss some organizational items — like the logistics of future workshops and the use of the MMMM GitHub, so that we can build up assets collectively, share them with the world and manage changes and contributions in a free-and-easy-but-organized way.

If you are coming , please bring:

• Yourself — If you’re a newb, welcome — If you’re an MCU Yoda, then attend you must and wisdom to newbs impart
• Some ideas
• A laptop if you have one
• You may want to install VMWare Player or VMWare Fusion before you arrive
• An MCU development kit if you have one or …
• Some money if you don’t.  We’ll have some development kits that you can buy.  Plan on at least $10 for the kits and some parts that you can use for small learning projects.
• A bread-board if you want to build some live circuits to keep.  We’ll have breadboards to loan, but if you want to take one home, it has to be one that arrived with you.

That’s about it — see you all Monday.  To whet your appetite, there is some prototype code below for reading a quadrature encoded position detector (not really elegant enough for a final effort, but it’s a start).  We’ll have you writing stuff like this in no-time.

This code is part of an effort to turn salvaged InkJet printers into motion controllers.  Most of these positioners let you position an InkJet head to within 1/600 inch — they’re fast, accurate, compact, surprisingly strong … and dirt-cheap.

#include  <msp430x20x2.h>

#define LED0 BIT0
#define LED1 BIT6
#define PHASE1 BIT1
#define PHASE2 BIT2
#define PHASE_MASK 6
#define PHASE_SHIFT 1

int state;     // used to hold current state of encoder bits (00, 01, 10 or 11) 
int lastState; // used to hold previous state of encoder bits (00, 01, 10 or 11) 
int pos;  // used to count steps. A 1/150" encoder (the most common kind) yields 600 steps per inck. 

// -- prototype of common bit of code used to compute the present state value 
void updateState(void);

int main(void)
{
	WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer 
	// --- set up some initial values 	
        pos = 0;
	P1DIR &= ~(PHASE1 + PHASE2); // Set P1.1 and P1.2 as inputs 	
        P1DIR |= (LED0 + LED1); // Set P1.0 and P1.6 to outputs. These are the LEDs on a LaunchPad. 

	// --- get initial conditions so that the first interrupt 	
 // has the right "edge" values and so that position calculations are based on feasible transitions 	
        updateState();
	lastState = state;

	P1IFG &= ~(PHASE1 | PHASE2); // clear interrupt flags for P1.1 and P1.2 	
        P1IE |= (PHASE1 | PHASE2); // P1.1 and P1.2 interrupt enabled 
	__enable_interrupt(); // enable all interrupts 	
 for(;;)
	{ /* just loop forever and let the interrupts do all the work */ }
}

// updateState() calculates updates for the edge detectors used in the interrupts 
// and also updates the "lastState" variable 
void updateState(void){
	state = P1IN & PHASE_MASK;

	if (state & PHASE1)
		P1IES |= PHASE1; // PHASE1 high, then interrupt on falling edge 	
        else
		P1IES &= ~PHASE1; // PHASE1 low, then interrupt on rising edge 
	if (state & PHASE2)
		P1IES |= PHASE2; // PHASE2 high, then interrupt on falling edge 	
        else
		P1IES &= ~PHASE2; // PHASE2 low, then interrupt on rising edge 

	// ---"right-justify" state so that it is in the range 0..3	
       state =  (state >> PHASE_SHIFT);
}

// Port 1 interrupt service routine #pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
    updateState();

    // --- test for all clockwise incremental cases      
 // if we stepped clockwise, then increment the position     
    if ( (lastState == 0 & state == 2)
       ||(lastState == 2 & state == 3)
       ||(lastState == 3 & state == 1)
       ||(lastState == 1 & state == 0)){
         pos++;
    }
    // --- If we didn't move clockwise, then we must have moved counter-clockwise     
 // so decrement the position     
    else{
        pos--;
    }

    // --- record last state     
    lastState = state;

    // --- update LEDs just to help debug     
    // use "state" as intermediate variable so that we can see the output value in the debugger easily     
    // This is just so that we can see the encoder signal. No functional purpose.     
    state = state + ((state << 5) & 0x40);
    P1OUT = state;

    // --- clear the interrupt flags     
    P1IFG &= ~(PHASE1 | PHASE2); // clear interrupt flags for P1.1 and P1.2  
}

We whipped up a Wiring-ish wrapper for the MSP430 a while back in order to simplify the task of porting Arduino libraries for use with MSP430 microcontrollers.  It turns out, we weren’t the only ones that thought of it.  PJ spotted a post on Hack A Day where someone unveiled something remarkably similar, and that post resulted in at least two other folks besides us posting their similar ideas — so there are at least four of these wrapper libraries out there.

Naturally, we’d like to think that ours is the best of the bunch, and the best named too — TIWrap.  Seriously, though, we seem to be genuinely different in that that we have bundled in actual libraries ported from Arduino, such as the HD44780 and MAX7221 libraries.  There are some piezo buzzer libraries and we expect to add some Charlieplexing utilities soon.  You can get a copy of TiWrap here.

The demo above is a “Fancy Flashlight” concept proposed by Matt Torbin.   It’s just one MSP430, two LEDs, a button and a bit of code which you can find in the TiWrap examples.

And in case the title left you puzzled …