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Cal Poly Pomona SPICE Physical Computing Discovery Collection Intro
Director: Barry Lehrman, Associate Professor of Landscape Architecture243
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Version: Summer 2021
blehrman@cpp.edu
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INTRODUCTION
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Physical computing connects the digital realm to the physical world, where people and phenomena directly interface with poetic to pragmatic algorithms.
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CPP’s SPICE (Special Projects for Improving the Classroom Environment) program is funding a ‘Tech Lending’ library for courses to utilize pursuing Project Based Learning assignments, such as prototyping Internet-of-Thing devices, machine vision/AI, environmental monitoring, interactive art installations, cosplay props and wearables, robots and more.
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This unprecedented collection features 60 Physical Computing Discovery Kits, each with a Micro-Controller (MCU) development board or Single Board Computer (SBC) accompanied by essential components, basic sensors, actuators, and tools required to learn the basics. These kits are augmented by a variety of components and a curated selection of 360+ analog and digital sensors, motors, servos, LEDs, displays, and networking and signal processing boards for students to try.
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Students can access items in the collection via Course Reserve (loan period of one week to one month). Items not reserved for specific courses have a loan period of one to two weeks.
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Instructors can reserve the 'Instructor's Kit' that contains a resupply of components for the Discovery Kits, additional components, connectors, tools and test instruments to assist students in their courses. The Instructor's Kit has a loan period of one week to one month (depending on demand).
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Please use proper ESD (static) safety precautions when handling static sensitive items (they are identified with warning stickers) - grounding straps and stations are available in the Instructor's Kit. Before handling any components, please ground yourself. Components and boards are packaged in ESD protective boxes and bags, please keep these in good shape.
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Documentation and Support
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Links to documentation and tutorials for the collection are provided on the other tabs in this file. Most of the boards and components in the collection are widely utilized across the maker community, so there are plenty of options for assistance. Products from Sparkfun and Adafruit were selected as much for their awesomeness as for the excellent support provided by those companies. For additional assistance, search the vendor's support forum and the internet, if you can't find the answer, then ask the instructor. Librarians, Maker Studio staff, and I&IT do not provide 'tech support' for items in the collection.
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SAFETY AND DANGER
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Playing with electronics can be risky. Students are required to review the following risk assessment items before proceeding to prototype their Physical Computing project. Failure to utilize proper safety equipment and to follow safety proceedures may have academic penalties or result in temporary to permanent lose of acccess to the Physical Computing Collection.
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See:
https://www.cpp.edu/~engineering/ECE/labs-2018/safety.shtml
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Description/TaskSafety Risks/Health HazardsPreventative StepsNotesATI - Accessible Technology
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Powering CircuitsElectric Shocks: from high voltage or high currents may cause minor to severe injuries, including burns, seizures, nerve damage, and potentially even death! Do not attempt to work with voltages over 24 volts, or high currents above a few amps without proper instruction, tools, and other safety precautions. Use extreme caution when connecting your circuits to 'mains' AC voltage (120v). Some of the power supplies may have exposed wires/terminals - DO NOT TOUCH WHEN PLUGGED IN!

ALWAYS unplug the power supply and/or batteries from a circuit before working on it. Single board computers have specific circuit shutdown procedures that must be followed to avoid damage (see the catalog entry or data sheet/tutorials).

Large capacitors (>1000uF) can provide a significant shock even at low voltage. Before handling, make sure they are safely discharged by shorting the leads with a high value resistor (1m Ohm) for several seconds (using insulated pliers/tweezers) - or borrow the capacitor discharge tool from your instructor or the Maker Studio. 		Make a capacitor discharge tool, such as: https://www.ifixit.com/Guide/Constructing+a+Capacitor+Discharge+Tool/2177
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Short Circuits: will damage circuit boards/components, and even start a fire. If the voltage/amperage is high enough, the short can create an arc/explosion. High heat can cause burns or damage property. Keep exposed wires/leads on the circuit board away from conductors, don't use metal tools to work on powered circuit. Inspect all wires/connectors and components for damage before powering up the circuit.

Use the correct sized power supply for the circuit and the correct motor driver/controller.

Install circuit protection components like resettable fuses (PPTC), thermistors, varistors, and TVS diodes to prevent over-current/over-voltage from damaging/overheating the circuit.
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Reverse polarity: connecting the power supply/battery backwards can damage or destroy the circuit board/components.Double check the correct connection orientation. Use polarized connectors to avoid reversed current, or include reverse polarity protection (such as a power diode).

Electrolytic Capacitors will be destroyed from reverse polarity current - make sure to identify the cathode and anode (typically marked with a negative sign and or the longer lead [VERIFY]) and confirm the circuit's polarity while assembling.

LEDs will only work when their polarity matches the circuit - if they don't illuminate, check that the polarity of their leads (there is often a flat side next to the Cathode [VERIFY]
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Over Voltage: too much voltage (even a fraction of a volt too much) can damage delicate components (such as LEDs and integrated circuits).Review the power requirements and logic level outputs for each component when developing your project.

All components and circuit boards available in through CPP Physical Computing Collection have the voltage requirements on the packaging and in the catalog entry. Some devices may utilize a higher voltage for power than the logic level they output or accept as inputs, so please make sure to verify the correct operating voltages before connecting all devices/components.

Always use a power supply with the correct voltage, or use a voltage regulator to ensure the circuit gets the correct Vcc voltage. Voltage regulators must be matched to the output current and voltage, as they can only safely dissapate specific wattage.

Use a logic level shifter to connect 3v3 to 5v logic level devices and vice versa.
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Over Current: too much amps or millamps will damage components, could cause a fire, or hurt you.LEDs are particulary sensitive to too much current, which is why they are usually paired with a resistor next to a LED in your circuit (220 Ohm for 3.3v and 560 Ohm for 5v circuits).

Heat generated by resistors, transistors, and other components from high current can be significant, please use heat sinks when appropriate to avoid burns or damage to the componts.
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Static ElectricityStatic will damage circuits, components, and sensors. Minimal personal risks as the current is very low, except you may be responsible for replacing damaged components and you may loose significant time trouble shooting/diagnosing faults caused by electro-static discharge (ESD).

Sensitive components are identified in the catalog, have ESD warning stickers on the packaging, and are stored in special ESD dissapative packaging. 		Wear a ESD grounding strap that is properly grounded before handling circuit boards and components. Alternatively, ground yourself by touching your computer's chassis (if plugged in) or a metal structure that is connected to the earth.

Avoid shuffling your feet while walking, or rubbing your arms/legs together.

Store ESD sensitive components in the provided packaging/bags. Insert the of IC's leads or the boards headers into the dissapative foam provided in the Discovery Kits or packaging. Please do not damage the packaging or allow it to get wet.

In the Maker Studio, there are electronic work area with a ESD protection including, grounded floor mat, desk cover, and grounding point for ESD wrist straps.

Use ESD preventative tools when handling sensitive components - ESD tweezers are provided in the Discovery Kits and additional ESD tools/protective devices can be check out from the Maker Studio or borrowed from your instructor.
Typical Voltages Required to Damage Electronic Devices:

* MOSFET 100 to 200 volts
* JFET 140 to 10,000 volts
* CMOS 250 to 2,000 volts
* Schottky diodes, TTL 300 to 2,500 volts
* Bi-polar transistors 380 to 10,000 volts
* SCR 680 to 1000 volts

Typical Electrostatic Voltages Generated by a Variety of Activities:

* Walking across untreated vinyl floor, 250 to 12,000 volts
* Moving a common plastic bag at a work bench, 1,200 to 20,000 volts
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 Prototyping CircuitsSharp Wires and edges on metal enclosures can cause cuts/scrapes/puncture wounds.Handle with care and use eye protection! Many parts of a circuit board and components can be sharp, not just wires, but the edges too. Deburr edges/file to remove sharp edges. Trim stubs of wire flush with solder.
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Trimming/cutting wires can cause flying shards to travel 10+ feet in random directions at high speed!!! Risks are eye injury, cuts/scrapes, or inhalation/injestion.Wear safety goggles!!!!! Keep your mouth closed.

When trimming wires, make sure the stub ends are pointing away from you (down is best!) and not towards anybody else.
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Pliers/Cutters/Crimpers can cause pinch injuries.Keep fingers away from pinch points.
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Cutters/Knives/Probes/Scissors can cause minor to severe cuts.Keep your fingers away from blades/sharp edges!!! Never place your fingers in front of the blade when cutting, always keep them to the side or behind the direction of the cut. Use a streight edge.

Replace the blade guard/cover when not using the tool. Store/carry sharp tools with the blade away from you.
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Lead/Cadmium/Arsenic/Mercury/Heavy metals: will cause nerve damage, neurological imparement (lower your intellegence and reduce your ability to regulate emotions/impulses), cause other severe health problems such as cancer or gastro-intestinal issues, and possible birth defects.Many components contain toxic heavy metals (such as CdS photoresistors). Choose components/boards that are RoHS (Restriction of Hazardous Substances - see below) complient - while these may seem to cost more, they will be higher quality and safer than the cheapest alternative.

DO NOT PURCHASE mercury tilt-switches (included in some cheap sensor kits) or thermometers - these will break and then you have a toxic spill.

Make sure to dispose of components properly - they are e-waste!!! Check with your instructor or maker studio staff.
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Lasers can cause temporary to permanent eye damage or blindness, burns, or potentially start fires!

It is illagal to shine lasers at air crafts or drivers.		Never point lasers at your or anybody elses face - they can cause eye injury (though the laser diodes in the kit are very low power and emit a frequency of light that has minimal risk to human eyes).
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LEDs can be very bright and cause temporary visual imparement (dazzle). Blue frequency light from LEDs/screens can disrupt your circadian rhythms and disturb your sleep.Do not look directly at LEDs at full brightness from close up. If you need to inspect a pixel, use very low power (10 to 20% PWM cycle).

Avoid working with blue LEDs late at night.
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Motors/Servos/Actuators can move at very high speeds or with sufficient force to cause injury from contact with moving parts (friction burns, cuts, or entanglement).

Motors and motor controller circuits can get hot enough to cause burns or start fires when malfunctioning/improper circuit design.

Motors/Solinoids/Electromagnets can pull so much current at startup that they can destroy an undersized power supply, heat up undersized wires, or damage other components in the circuit.

Mechanical failures/vibration can propel sharp peices at high speeds across the room.		Keep your fingers and HAIR away from moving parts to avoid injuries from pinching/friction burns/entanglement. Use guards/cases to enclose moving parts.

Wear eye protection when working with high speed mechanisms, to avoid injury from failure.

Review the data sheets to identify the power requirements for the device and double check that you properly connect the power and controlling circuits to the motor.

Isolate the microcontrollers/SBC/sensors from the high voltage required by the actuators with a dedicated low-voltage circuit with decoupling capacitors, and/or opto-isolators, and fly-back diodes.
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High Volume sound can cause temporary deafness, or permanent hearing loss.Sounds emmitted by piezo buzzers, speakers, earbuds/headphones, or ultrasonic transducers can be loud enough to disturb others or cause hearing loss. Make sure to turn the volume down all the way before connecting power to an audio device or before unpluggimg any headphones/microphones (better yet is to shut off the circuit).
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SolderingItems in the Physical Computing Discovery are plug-n-play and do not require any soldering before use (this was done by the project's student assistants/PI). But you may purchase components that require soldering to assemble.
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Hot Soldering Irons and Solder will cause 2nd or 3rd degree burns/severe eye injury!Situational awareness is critical when soldering or when working nearby.

Avoid touching the (hot) tip of the iron, only hold the insulated handle, properly stow the iron in the holder when not in use. Hair must be pulled back/secured to avoid contact with iron.

Don't wear loose clothes. Wear closed toed shoes to avoid burns from dripping solder.
Use soldering stand (don't lay hot iron on the table)
Use high temperature resistant soldering mat to protect work surface.
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Fumes from Soldering Flux and Solvents are toxic. Avoid breathing them!

They cause throat/lung irritation, nerve damage, intoxication, and eye irritation. 		Review MSDS for safe handing of soldering chemicals and use proper safety equipment: eye protection, fume extractor, gloves, et cetera.

Solder and use the cleaning solvents only in spaces with good ventilation!!!!
Use the fume extractor to pull the fumes away from your face - the closer the work-piece is to the extractor, the lower your exposure to the fumes. Keep your face away from the fumes - use a magnifying glass/loope to clearly see the work are.

Fumes may be adsorbed into your clothes (and hair), so use a lab coat/smock to leave the fumes at work and to avoid exposing others to third-hand fumes.
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Lead: supposedly there are minimal health risks from the lead in solder (either while soldering or from handling circuit boards assembled with it). But this is an easily avoidable risk - ALL Physical Computing Discovery Library items that needed final assembly were fabricated using lead-free solder. Most of the circuit boards/components are ROHS certified as lead-free (but not all) - check the data sheet to confirm.Cheap/old components are often fabricated using leaded solder as it is 'easier' to work with.

Do not eat while soldering - period. Even lead-free solder isn't intended for injestion, so do not eat while soldering. (Okay to sip a beverage as long as you don't touch the straw/lips of the container)

Do not eat while handling components/circuit boards that are known (or suspected) to use leaded solder. Wash hands immediately after handling items. Do not stick wires/components in your mouth (duh!!!!) or chew on the insulation.
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RoHS bans the use of lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB), polybrominated diphenyl ethers (PBDE), and four different phthalates (DEHP, BBP, BBP, DIBP).
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Restriction of Hazardous Substances (RoHS)RoHS bans the use of lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB), polybrominated diphenyl ethers (PBDE), and four different phthalates (DEHP, BBP, BBP, DIBP).
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The ROHS status for components in the Discovery Kits is listed in Column K of the /Discovery Kit Component Tab
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