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MAKE Newsletter

October 8, 2010

Welcome to the Make It Last Build Series Newsletter!

We're so glad to have you on board for the Make It Last build series! And we're thrilled that Microchip and Energizer are sponsoring this contest.

The goal of this build series is to take a more in-depth look at projects that involve microcontrollers, and to understand how to design circuits that work with low power -- to better understand that relationship between microcontroller and power. During the course of this series, over the next few months, we will be doing three builds. For the first challenge, your build must be powered by a battery, and be capable of sensing and recording something in the environment (i.e. a "data logger"). The example project will be a simple data logging circuit that stays in one place, however it is designed to be flexible -- if you think it might make more sense for it to be able to move around, or alert a user if it notices that something drastic has happened (the freezer is on fire?), then that would be awesome -- the sky's the limit!

These newsletters will provide weekly updates about the contest, including each step of the build, explanations about each of the pieces that make up a microcontroller system, and provide inspiration and guidance to help you put your project together. The official contest rules and regulations can be found on the contest landing page , which also houses the official sign-up form and links to everything about the contest. We'd love to hear from you, so don't hesitate to contact Matt or Gareth with any questions or concerns you might have about the builds. We've also set up a forum topic specifically for this contest, so be sure to stop by and introduce yourself!

As a reminder, this contest is open to anyone who wants to learn about microcontrollers. Whether you're a seasoned programmer who wants to learn a bit more about hardware, or a beginner just starting to get your feet wet, don't be shy! We're looking forward to seeing how much we can all learn in the coming months.

Cheers,
Matt and Gareth

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First Build: The Data Logger

 data_logger.jpg

The first project that we're going to undertake is a simple data logger. This is a battery-powered device that can periodically sample the temperature and record it for later analysis. It's basically like a thermometer combined with a recording device -- you could track the temperature of your home, refrigerator, personal volcano, or anything else over a long period of time, using a single pair of batteries. To save battery power, the device will spend most of its time in a reduced-power 'sleep' mode, only waking itself up every so often to measure a temperature probe before going back to sleep. Using this strategy, the device should be able to gather data for months on a single set of AA batteries.

We'll cover how to wire up the board, program the chip, and test the project in the coming weeks. If you're planning to build along, now's a great time to look through the parts list and order any of the parts that you need! It's also a good time to start thinking about what you would measure, and how you could react to this data. Is there something else (light, noise level, wind) that it should be recording as well? Should this be just a measurement tool, or should it try to react to its surroundings? I'm starting to think of designing a mechanical flower that opens in the sunlight or a robot pet that curls up when it gets too cold inside. What would you make?

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Gathering the Parts

Here's a list of the parts that we will be using for this first build. There are a reasonable number of components, however you might already have many of them on hand. The value of the resistor and capacitors have some wiggle room, so if you have something close it might work as well.

Tools:

  • PIC programmer, for programming the processor (we'll be using the PICkit 3, $44)
  • 3.3V FTDI cable (for sending data to the computer)
  • Digital multimeter that can measure current

Parts list:

  • Microcontroller: Microhip18LF25K22 (Digikey PIC18LF25K22-I/SP-ND, $3.14)
  • Temperature sensor: Microchip MCP9700A (Digikey MCP9700A-E/TO-ND, $.34)
  • External EEPROM memory (for storage): Microchip 24AA1025 (Digikey 24AA1025-I/P-ND, $4.32)
  • Solderlesss breadboard (Digikey 438-1045-ND, $8.73)
  • 2xAA battery holder (Digikey #SBH-321AS-ND,$0.89)
  • 10x3mm red LED (Digikey 754-1218-ND, $0.10)
  • 1uF capacitor (Digikey #P5174-ND, $.20)
  • 100k resistor (Digikey #CF18JT100KCT-ND, $0.09)
  • .1" male headers (Digikey #A26509-40-ND, $1.60)
  • Breadboard jumper wires (Made from solid core 22AWG wire, the more colors the better)
  • 2 AA batteries

Optional (for making a permanent version):

  • Soldering iron
  • Solder
  • Breadboard

 

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Microchip Discount Code

Want to pick up a PIC programmer or development kit? As part of the contest, Microchip is offering a 20% discount on the following development tools:

PICkit3
PICkit3 Debug Express
ICD3 In-Circuit Debugger
XLP 16-bit Development Board
F1 Evaluation Platform
F1 Evaluation Kit

If you've been thinking about getting started with PIC programming, this could be a great opportunity to get a good deal on a programmer. To request a discount code, send an email to makeitlast@makezine.com.

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