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Lesson Simple Wearables

    This workshop was first delivered as part of American Express’ CodeGirls programme at Amex Football Stadium, Brighton, December 2014.

    Link to main project page

    Video of Presentation Slides for the workshop.

    simple wearables


    STARTER:

    5min: Play video of wearable tech. http://youtu.be/4qFW4zwXzLs
    5min: Discussion: What does it mean them “wearable technology?”

    TASK 1:

    15min In pairs or small groups: Design a Wearable Tech item for use in the Stadium (now or future technology). This is a sky’s the limit activity. This item could be for players, fans or staff at the stadium.  It could a fun or practical item.

    What does the item do?
    Who is it for?
    Why would they want the item?
    How do they think it might work?

    Students will be expect to design and create their own “light up  integrating a sensor circuit” using the skills acquired during the day. Demo the different kit or similar to show what can be achieve with a little hard work.

    THINK : Get the students to the think about circuits.  How and why do they work.

    Hand out the Kit

    TASK 2: Circuits

    10 mins: Design different layouts  (atleast 3) for the their wearable piece. Starting with where they want the lights, how are they now going to connect them? Do they need to modify their layout to get their design to work? Get them to use dotted lines to represent the stitching, small circle for LED, Large Circle for Gemma and larger rectangle labelled + – for the battery.  If possible bluetack all the design to the wall and get the students to review the design for technical and aesthetics. 

    COMPARE: Get the students to share their designs and work together to make them work.

    NOTE: the + and – cannot cross as this will cause a short and the project wont work

    TASK 3:  Stitching Time

    30mins++ mins: Stitching the lights, board, sensor and power. Using their Circuit designs.
    Allow enough time for the students to correct any mistakes – like crossing wires, + and – touching.  Battery connection not strong enough. And general needle issues!

    TASK 4:  Arduino Programming (optional)

    http://www.artofcs.org/project/light-up-with-gemma/ This part of the workshop / class can be done before starting the simple non-programmable wearable task (from task 2).

    Using pre-soldered and pre programmed Gemma and Neopixels demonstrate the working headdress. Ask the girls to pick 3 colours and fine their RGB values using http://www.colorpicker.com/ or similar tool.  This is one of the simpler colour pickers

    Now modify the code by adding their colours into the loop called void loop

    SHOW N TELL.  10 mins All Students to demo their cool wearables!

    Teacher Help Notes:

    Curriculum Links

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    Delivering the session

    As a lead tutor, your role will be to guide the students through the activities.  This will include proving the students with the technical understanding necessary to complete their project, while prompting and encouraging the development of creative problem-solving and design skills. Encourage the students to questions, reason about, and revise their current understanding (mental model) as well. The process of delivery is just as important as the outcome in this workshop.

    Remember to encourage collaborative learning approach. Those who already know hot to sew can assist peers who may lack sewing skills or experience. Likewise, students with knowledge of electronics can help those who have less familiarity with this area.

    Consider starting each task by connecting back to the previous task or classroom/curriculum links. Recap and use their answers from task 1 as this helps students develop and consolidate their current learning and refocusses the student back on task for the activity.

    Conclude the workshop by asking the students to take turns presenting their work to on another.  Prepare the students for this as they may initially be embarrassed but by the end of the day be more willing to participate. Encourage the students to share thought behind the aesthetics behind the design of their project, on top of an explanation of how their circuit functions. This is a good time them to share any difficulties that they encountered and managed to overcome.

    Glossary:

    Microcontroller: A small computer on a single integrated circuit contains a processing core (CPU), memory and programmable input/output peripherals, in this workshop’s case it is the Adafruit Gemma. micro controller are used in automatically controlled products and devices such as remote controls, appliances, power tools, medical devices and toys.  The very first single chip microprocessor was realised in 1971.

    LED: There are different types of LEDS, the ones soldered to the Gemma are smart because they have a chip in them that communicates with the main controller (Gemma).  we are using simple LEDs to stitch the mini wearable. LEDS in general – Surface mount devices (SMD) are more common than ever thanks to miniaturisation. LEDs inside disk drives, modems, and small personal electronic devices are more often SMD devices these days. Most of the size of a 5mm or 3mm indicator LED is the epoxy package–the actual LED junction is quite small. With SMD LEDs, you don’t get much extra packaging, just the glowing bits. Without the epoxy package focusing the beam, they tend to have wide viewing angles, and are often used with light pipe in a device.

    SMD LEDs are available in four sizes, which are designated 1206, 0805, 0603 and 0402 . 0402 is the smallest, with overall package size of 1.0 mm x 0.5 mm x 0.45 mm (L x W x H). Then 0603 at 1.6 mm x 0.8 mm x 0.6 mm. 0805 are slightly larger, at 2.0 mm x 1.25 mm x 0.8 mm. 1206 are the big brothers of the family, at 3.2mm x 1.5 mm x 1.1 mm.

    Resistors: Why do you need a resistor with an LED? The short answer: to limit the current in the LED to a safe value. As we are only using a few LEDs we can safely complete the project without a resistor.

    The long answer: LEDs are semiconductors, diodes in particular. The current flowing in an LED is an exponential function of voltage across the LED. The important part about that for you is that a small change in voltage can produce a huge change in current. That is the most important concept of this article. Resistors aren’t like that. The current and voltage in a resistor are linearly related. That means that a change in voltage will produce a proportional change in current. Current versus voltage is a straight line for a resistor, but not at all for an LED.

    Because of this, you can’t say that LEDs have “resistance.” Resistance is defined as the constant ratio of voltage to current in a resistive circuit element. Even worse, there’s no real way to know exactly the relationship between current and voltage for any given LED across all possible voltages other than direct measurement. The exact relationship varies among different colours, different sizes, and even different batches from the same manufacturer.

    When you buy an LED, it should come with a rating that looks like this: 3.3V @ 20 mA typical. That gives you one point along the operating curve. Usually that’s a safe operating point. You may get a maximum rating in addition. It may be in the form of either a voltage or current. For example, a lot of people report buying “5V blue LEDs.” These are really not rated to operate continuously at 5V in most cases.