Knitty: little purls of wisdom
Mortaine
Title
beauty shot

Yep, this bag knows everything. It knows your row number, the chart for your stitch pattern, and where you are in that stitch pattern. Unlike the other know-it-alls in your life, it will gladly share information with you by displaying your row number and a chart for the current row of your stitch pattern in lights! (Though of course there are limitations; you can generate a custom chart for the bag, but only for stitch patterns up to 10 stitches wide that use k, p, k2tog, ssk and sk2p).

The bag is part of a growing project category called “computational textiles.” Computational textiles is a scary phrase often applied to projects that are complicated, difficult and fun but don’t do much. Still, I found myself obsessed with the idea of mixing knitting and technology after making an origami crane with light-up eyes at a computational textiles workshop at Indiana University.

This bag is the result of that obsession. The 10 LED lights act as a row counter and a charted pattern. And more important: just about any knitter could pull this off.

Really. Any knitter with a thirst for adventure and a few projects under their belt can do this.

You can make and use this bag if you can:

  • Knit
  • Purl
  • Seam using whipstitch (not even mattress stitch!)
  • Thread a needle without poking yourself (for the sewing, and my weakness)
  • Poke yourself while threading a needle (for the needle felting; in fact, this was my first-ever needle-felting project!)
  • Read knitting charts
  • Sync an iPod or cellphone with your computer

Here’s how it works: a tiny computer chip gets connected to LEDs using metal-coated thread. The computer chip sends signals to the LEDs—all on (knit), all off (purl), flicker (yarnover), etc.—and poof, your knitting pattern lights up. Want to see the next row? No problem! Just press the button and the next row displays.  Need to turn the bag off until tomorrow? No problem! It saves the row you were on, even if you remove the battery. The video below explains just how the bag works. It's very neat.

spacer model: Erin Corber spacer photos: Kalani Craig

SIZE
One

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FINISHED MEASUREMENTS
Width: 9 inches
Height: 7 inches
Gusset depth: 1 inch
Note: Measurements taken after felting.

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MATERIALS
Yarn

Cascade 220 Heathers [100% Peruvian highland wool; 220yd/201m per 100g skein]; 1 skein each color
spacer [MC] #4011 Sparrow
spacer [CC] #9448 Olive

Recommended needle size

[always use a needle size that gives you the gauge listed below -- every knitter's gauge is unique]
spacer 1 set(s) US #10.5/6.5mm straight needles

Notions
spacer Locking stitch markers or safety pins
spacer Row counter (optional)
spacer Yarn needle
spacer #12 or #16 crewel/embroidery needle (or needle that will fit into holes in LilyPad and LEDs)
spacer 1 medium-gauge felting needle
spacer 1 2” thick block of foam (4”H x 4”W x 2”D)
spacer 1 tube puffy fabric paint

Click here to add all of the parts listed below to a cart at sparkfun.com
spacer 1 LilyPad Arduino Pro Kit (DEV-08873 at sparkfun.com; includes a main board, a USB connector, and a AAA battery power supply)
spacer 10 LilyPad Arduino Bright White LEDs (DEV-08735 at sparkfun.com)
spacer 1 LilyPad Arduino Button Board (DEV-08776 at sparkfun.com)
spacer 10 yards conductive thread (DEV-0938)

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GAUGE

spacer10 sts/13 rows = 4" in stockinette stitch, before felting
Note: It is not critical to get exact gauge for this piece. Size can be manipulated during felting process.

PATTERN NOTES
[Knitty's list of standard abbreviations and techniques can be found here.]

sk2p: Sl 1, k2tog, pass slipped st over. 2 sts decreased.

Can't work with wool?
Part of what makes the electronic circuitry stable and keeps short circuits from forming as the fabric moves and twists is the thickness and solidity of felted wool. That said, any fabric that's very tightly knit can form the base for a non-wool version of this bag. Pay careful attention to the idea of how short circuits form and keep in mind that as non-felted knitted fabric shifts, the conductive thread sewn through that fabric shifts too. Puffy paint is less effective in isolating circuits that are sewn in non-felted knitted fabric, unless the fabric is thin (think t-shirts).

A non-wool version of this bag would benefit greatly from experiments with the shape of the bag and, in particular, the placement of the different components. Consider rearranging the placement of the LilyPad, the button and the LEDs in order to minimize the number of times that a positive-circuit line of conductive thread has to cross over a negative-circuit line of conductive thread. Sketching out your own grid on a whiteboard or chalkboard using different colors for positive and negative circuits will help you visualize the circuit first. Then you can use the newly-drawn circuit to re-engineer the shape and size of the bag itself.

Using the bag: Insert a AAA battery into the battery holder to turn on the lights.

The LilyPad saves the last row you were on.

To move forward a row, press the button you sewed onto the bag.

To flash the row number, press the button on the LilyPad itself.
For example, for row 7, the first 7 LEDs will light up for 4 seconds. For Row 14, the first LED will light up for 4 seconds, followed by the first 4 LEDs lighting up for 4 seconds.

Light Key:
Knit: light on
Purl: light off
k2tog: long blink (1 second)
ssk: short blink (0.5 second)
yo: flicker (0.1 second)
sk2p: 2 long blinks, followed by 1 short blink

Sewn electronic circuits at work: The LEDs on this bag light up because they’re sewn using a basic electronic circuit connected to a tiny computer board, which is in turn attached to a battery.

The circuit forms an uninterrupted loop divided into a positive side and a negative side. In sewing terms, that means a piece of metal-covered conductive thread is sewn from one of the pins on the main board to the positive end of an LED (see figure below). A second piece of conductive thread is sewn from the negative end of the LED to the negative-ground pin on the main board. Electrical current flows through the resulting loop, sending power and commands to the LED. A more detailed tutorial on how the LilyPad works is available here.

For the Know-It-All Knitting Bag, each of the 10 LEDs and the row-counter button has its own numbered pin on the main board. When the board is plugged in to its power source, the little computer chip sends a message to each numbered pin in a programmed order to turn that pin’s LED light on and off. Voilà, a knitting chart!

Avoiding short circuits: The LEDs each have their own numbered positive pin, but they all connect to the single negative-ground pin on the board to complete the circuit. If the negative half of one circuit touches the positive half of that circuit, or if the positive side of one circuit touches the positive side of a second circuit, the electric current that flows in a circle will be interrupted by the new contact with part of another circuit. The result: a short circuit.

To keep that from happening, we’ll use a carefully designed set of sewn lines (see circuit pattern in Finishing section), the thickness of felted fabric, and a little puffy paint to help isolate each of the LED circuits. The circuit diagram below provides a guide to the sewn circuits, but it’s important to keep one sewing tip in mind: unless you’re tying off a knot, never insert the needle all the way through the fabric. Instead, insert the needle parallel to the fabric halfway so the thread runs through the fabric, as shown here in this cross-section of felted fabric.

It’s also important to cut your thread and tie it off after finishing a positive circuit rather than sewing down the LED through the positive end and using the same piece of thread to then sew down the negative end of the LED. Using the same thread without cutting it effectively connects the positive and the negative circuits in the bag, and that means (yep, you guessed it) a short circuit.

Directions for whip stitch can be found here.

Making strong, stable electric connections with conductive thread: Conductive thread is fairly thin, so a strong connection to each pin is vital to create a stable circuit. To create a strong connection between the thread and the pin, work the thread around the hole in the pin several times, until it’s impossible to get another strand of conductive thread through the hole in the pin.

Conductive thread also has a tendency to fray. To keep the finished product neat and tidy and prevent any accidental shorts that might result from stray ends, leave a tail at least 0.5 inch long after tying each knot, until you’re instructed to trim excess thread from the knots.

Caring for the electronic circuits in computational textiles
The Arduino LilyPad is washable. That's right, washable. These circuits were designed to be added to clothing, so they can get wet and even be washed. Still, there are a few caveats.

First, conductive thread can rust a little if it's exposed to harsh chemicals or doesn't dry properly. For a felted bag, that means avoiding most normal laundry detergents and aiming for good ventilation during the air-drying process (depending on the humidity, that may mean careful application of a stream of warm air from a hair dryer, avoiding the LilyPad itself, the button, and the LEDs).

Second, and most important, the battery should always be removed before the bag gets wet [or if you get unexpectedly caught in the rain, as soon as possible]. There's little chance that the bag or any part of its circuits will get hot, catch on fire or melt down, but too much current (and the potential for a short circuit if water connects the positive and negative circuits) can actually fry the delicate computer chip that runs the LilyPad.

 

DIRECTIONS
BAG BODY
Using MC, CO 28 sts.

Work 100 rows in stockinette st, placing locking stitch markers or safety pins through first and last sts of rows 46 and 54.

Using CC, work 9 rows in stockinette st.

Using MC, work 9 rows in stockinette st.

BO all sts using two strands of CC held together.

STRAP/GUSSET
Using CC, CO 9 sts.

Work 46 rows in stockinette st.

Work 150 rows in garter st.

Work 46 rows in stockinette st.

Loosely BO all sts.

Stockinette st portions form side gussets of bag; garter st portion forms strap.

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FINISHING
Seaming:
Note: Recommended sewing technique for this bag is whip stitch, worked with right sides together (wrong sides facing out), sewn loosely, working a half-stitch in from edge instead of full stitch in from the edge to keep the seam from getting too bulky. Working seams in this way will allow seams to felt at the same rate as the rest of the bag.

Using MC, sew each end of strap/gusset to side edges of bag body, between markers; take care not to twist strap when sewing second end.
Sew side edges of shorter side of bag body (side without CC stripe) along edges of gussets. Sew side edges of longer side of bag body to remaining edges of gussets, leaving top portion of bag body free to form flap.
Weave in ends.

Felting: Felt bag to given dimensions. Drain and spin to remove excess water. To make blocking form, stuff newspaper into plastic bag and shape to desired measurements. Insert blocking form into felted bag and allow to dry completely.

Needle-felted grid: Needle felting uses a barbed needle to force wool strands to interlock and felt. By pressing the needle repeatedly through a single strand of yarn layered over the fabric of the bag, you can create a grid outline just like the grid lines that divide symbols in a real knitting chart. Try needle felting on a hidden part of the bag (or on a felted swatch) before working the needle felted grid, to get the hang of the technique. Needle must be stabbed into wool components many times before they will be securely joined.
Important tip: Place the block of foam behind the felted fabric before beginning. Don't forget to do this; felting needles are very sharp, and will damage whatever is behind the fabric. You can also accidentally felt the front and back of your bag together if you don't place something inside the bag.

Lay bag flat with bag front facing up, making sure that folds along side edges of bag are along center of each gussets
Using needle-felting tool and a single strand of MC yarn, form needle felted lines on vertical dark stripe formed by gusset along right hand side of bag front. Divide the green that shows on the front into 10 equal vertical sections, as shown in red on the diagram below. Note that grid should only be as wide as front portion of gusset (half of gusset width).

IMPORTANT: Read all Pattern Notes before proceeding!

Sew the positive half of the circuits: Using conductive thread doubled and a #12 or #16 crewel/embroidery needle, use the circuit guide below to sew  positive ends of the LEDs and the single button to the positive numbered pins on the LilyPad.

Solid lines denote backstitch embroidery paths that show on the front of the bag; dotted lines denote running-stitch paths that are on the inside of the bag and don’t show.

Back Stitch:


Running Stitch:


Isolate the positive circuits: Do this all in one sitting. Trim all of the excess conductive thread from the knots. Place a dot of puffy paint over each knot, using the puffy paint to make sure the conductive thread of the knot doesn’t touch any other conductive thread. Then use the puffy paint to paint over the lines of conductive thread on the inside of the bag (the dotted lines in the positive-circuit diagram above). Let dry for at least 8 hours before continuing.

Sew the negative ground for the circuits: Using an extra-long piece of conductive thread doubled and the circuit grid below, sew the negative pin of the LilyPad to the negative end of the LED at the very bottom of the purse.

As you sew up the side of the purse, hook the negative LED ends to this long negative circuit one by one using a hidden running stitch without cutting the conductive thread. Once all of the LED negative grounds are attached to the negative circuit, work across the top of the bag, straight down to the negative-ground pin on the LilyPad and to the negative ground on the button, all with the same strand of conductive thread.

For the sake of clarity, the positive half of the circuit is shown in light blue; the negative ground is shown in bright yellow. Solid lines denote backstitch embroidery paths that show on the front of the bag; dotted lines denote running-stitch paths that are on the inside of the bag and don’t show.

If you see a positive circuit covered with puffy paint, use the puffy paint as insulation to make sure the positive-circuit threads and negative circuit threads don’t touch.

Isolate the negative circuits: Do this all in one sitting. Trim all of the excess conductive thread from the knots. Place a dot of puffy paint over each knot, using the puffy paint to make sure the conductive thread of the knot doesn’t touch any other conductive thread. Then use the puffy paint to paint over the lines of conductive thread on the inside of the bag (the yellow dotted lines in the negative-circuit diagram above). Let dry for at least 8 hours before continuing.

Upload the default leaf-lace LED pattern to the LilyPad: Follow the directions here to download the Arduino software and connect your LilyPad via USB port to your computer.

Then click to download KnowItAllBag.pde and save it on the Desktop of your computer. In the Arduino software, select “Open” from the “File” menu and navigate to your desktop. You should see KnowItAllBag.pde. Select that file and press the “Open” button. Now follow the uploading instructions (steps 2 and 3 here) to upload KnowItAllBag.pde to the LilyPad. Test the pattern!

The default chart included in KnowItAllBag.pde is adapted from Fern Lace in Barbara Walker’s Treasury of Knitting Patterns.

Note: Chart shown is for demonstration purposes only. If you knit an item following this chart, the stitch pattern will offset 1 st to the left in Row/Round 15. To compensate, the end of the 10-st pattern repeat must be moved one stitch to the right, at the end of Row/Round 14.

Sew in the power source: Place the battery holder inside the bag in a location near the LilyPad that will be convenient for you.

Using conductive thread doubled, sew one of the negative grounds of the battery holder to the negative pin or any part of the negative circuit on the inside of the bag. Trim knots and use puffy paint to isolate the negative power source ground. Let dry for at least 8 hours before continuing.

Using conductive thread doubled, sew the positive pin of the battery holder to the positive pin on the LilyPad (between the negative pin and the #5 pin). Trim knots and use puffy paint to isolate the negative power source ground. Let dry for at least 8 hours before continuing.

Generate a custom knitting pattern or row counter:
To generate a program for a custom stitch pattern, pick out a chart pattern that's up to 10 stitches wide and uses k, p, k2tog, ssk, and sk2p. (You could substitute another stitch for one of these stitches as long as you're consistent in your substitution.) For charts of less than 10 sts, the unused LEDs on the left-hand side of the bag will simply remain unlit.

To prepare your chart, type it out using the XRX knitters font abbreviations or the typed abbreviation of the stitch presented in the key above and follow the generator's directions for saving the new .pde file.

To generate a custom row counter, download KnowItAllBag_RowCounter.pde and save it on the Desktop of your computer. In the Arduino software, select “Open” from the “File” menu and navigate to your desktop. You should see KnowItAllBag_RowCounter.pde. Select that file and press the “Open” button. Change the number of rows in your pattern on line 26 of KnowItAllBag_RowCounter.pde.

Now follow the uploading instructions (steps 2 and 3 here) to upload KnowItAllBag_RowCounter.pde to the LilyPad. Test the pattern!

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ABOUT THE DESIGNER

Kalani Craig is a PhD candidate in Medieval History at Indiana University. A native of Portland, Ore., Kalani is devoted to the twin arts of coffee and wine drinking and amuses herself by reading funny bits of medieval Latin out loud. The record of her adventures, knitting and otherwise, is intermittently updated at hapagirl.com.

Inspirational thanks to Kylie A. Peppler from Indiana University’s Learning Sciences program, Leah Buechley from MIT Media Lab’s High-Low Tech Group, and their teams for holding the computational workshop that started this project.

The workshop and LilyPad materials were funded by a grant from the National Science Foundation to Kylie A. Peppler (NSF-0855886).

Particular thanks are due to Joshua Danish and The Best Knitting Group Ever for helping solve several of the engineering and design obstacles that helped make the Know-It-All Knitting Bag a practical possibility for any knitter instead of a specialty toy for a few select geeks.

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