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The Affordable Internet of Things

(How to Connect More for Less)

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Convergence of Two

We have all heard that EVERYTHING will be connected some day in the very near future. Arduino has exposed countless numbers to the idea that they can program MCUs to do what they want.

As I like to say getting a new tool opens up design space in your head.

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IoTThere are shields to do just about anything you want and they are great, you stack them up and go to town.

As an example: WiFi shields cost anywhere from $30 to $84.95 from Sparkfun. How are you going to put a bunch of stuff on the IoT at those costs? You aren't, you will have to wait until someone else does in volume to get the price down and hope it does what you want.

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Another Way!

No Maker wants to wait for someone to design the device they want.

Along comes the ESP chips allowing you to use them to get on your local WiFi net for less than $5, what a deal.

People dug a little deeper and found there was of course an MCU controlling the WiFi with extra functionality available.

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Example Sensing Soil MoisturePlug and Play Arduino

Shield ApproachB.O.M

UNO $10

WiFi Shield $40

Sensor $5

Power Supply $5

Total $60

The Cheapest Approach

B.O.M

Benefit: easy to assemble truly plug and play, any vendor can support itDrawback: Cost and size, how many plants are you going to do at $60 a piece.

ESP-01 $4

Sensor $5

Power Supply $5

Total $14

Benefit: Cost and size, assembly required, lower powerDrawback: Assembly required, external programmer

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Soil Sensing (cont.)Crazy Talk – How can assembly required be both a benefit and a drawback?We are Makers right, so why not get your hands dirty, warm up the soldering iron.

Another way to look at it is this, what chances do you have of a little fireworks display if you just take and UNO, a sensor and a shield and plug them together. Conversely, get that soldering iron out and you can make a smoke bomb of your own.

Moral, buy a couple of each component

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NodeMCU

Resources 10 GPIO Serial Port I2C SPI WiFi 1 ADC

No External Programmer Needed

3.3 Volts

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NodeMCU (cont.)

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Arduino in a 3.3 Volt WorldMore and more sensors every day operate

at 3.3 V. The standard Arduino's operate at 5V, granted they supply 3.3 V output to power the sensor but the lines all run at 5V.

Some sensors have I/O that is 5 V tolerant and some don't and on you will have early EOL on some by using 5 V I/O.

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Arduino in a 3.3 Volt World (cont.)

Join the 3.3 V movement don't fight it. Use Arduino Pro Minis running at 3.3 V.

The Pro Mini has all of the functionality of the UNO with the exception that you need an external programmer.

Not only is the Pro-Mini smaller it is cheaper about $3-4 on ebay For battery operated systems like many IoT nodes the Pro Mini is a winner because it runs at 8 MHz, instead of 16 MHz.

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Arduino Pro Mini

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External ProgrammersFor Atmel chips the Cadillac is the

AVRISP MKII, it is fast, hard to kill and works with all the Atmel AVR MCUs. Drawback price ~$30 and it does not supply power.

There are many others my favorite is the FTDI programmer because it can also be used for programming the ESP chips we talked about earlier. Buy one that allows for both 3.3V and 5V operation and buy one from a reputable dealer not ebay.com too many have counterfeit FTDI chips.

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External Programmers (cont.)

Beware of buying FTDI programmers on ebay as there are many, many counterfeit FTDI chips that are of very poor quality. Buy this one from Microcenter in Saint Louis Park as it is a real FTDI chip offers both 5V and 3.3 V with a switch to select for less than $10, a good deal.

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BluetoothThink of your smartphone as a data display, input and data storage device. The Bluetooth Arduino shields are bulky they cost $10 or more and aren't compatible with Pro-mini's which by now everyone is convinced is the only way to Arduino.

Enter the HC-05 Master/Slave Bluetooth available on ebay for about $3.50. Use the HC-05 wherever you would use wires for a serial port.

Buy this one

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Bluetooth (cont.)

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Bluetooth (cont.)

So you have a project with Bluetooth what do you connect with.

Go to the app store of your choice and search “Bluetooth Serial Terminal” or similar and install one.

You can use your Smartphone to great effect as a display and storage unit. Go to http://evothings.com for tools to easily build custom interfaces with your Smartphone.

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RFDuino

A really big finger or a small Arduino?A really small Arduino with low-energy Bluetooth!

Here is the RFDuino in a package ready for prototyping. An external programmer is needed, use your FTDI board (3.3V) not the shield they sell.

rfduino.com

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MORE POWER!!

Maybe you find that you need either more memory or processing power but want to stay in Arduino, what's a Hacker to do?

Teensy3.1 offers a full 32-bit ARM processor running at 72 MHz with all the capabilities available to the ARM world and still use the warm and fuzzy Arduino IDE. A great solution at less than $20

http://pjrc.com/store/teensy31.html

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Teensy 3.1

The Teensy 3.1 is probably the most powerful processor available through the Arduino IDE, at less than $20 it is an amazing deal.

Often people will ask can I process images with Arduino and the answer has always been no, with Teensy 3.1 you can process images.

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PCB Options

After you have breadboarded a design up you may want to make multiple permanent installations of it. You can import your design into Eagle or similar to design your PCB.oshpark.com is a great resource for fabricating PCBs in small runs. Osh Park charges $5 per sq inch for 3 PCBs of you design, great for prototyping or very small runs.

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PCB Options

A next step up for PCBs if you need more than 3 is iteadstudio.com, they offer some great service like 10 copies of a maximum size of 5 cm x 5 cm for $10. Iteadstrudio is cheaper than oshpark but it takes 4 weeks or more versus Osh Parks 10-12 days.

http://imall.iteadstudio.com/open-pcb/pcb-prototyping/im120418001.html?options=cart