Category Archives: Electronics

Don’t Be Afraid of Surface Mount Components!

While taking stock of the components I had on hand last weekend I found a small box of sample components that I had ordered from Maxim a while back; Two each of several components: DS2717 RTC, DS2438 Smart Battery Monitor,  DS2762 Hi-precision Li+ Battery Monitor with Alerts, and an DS2408 8-channel addressable switch.  These parts all have a couple things in common – first, they are all 1-Wire devices, but more to the point they are all surface mount components.  The 2717 is a TSOC-6, the 2438 is a SOIC-8, the 2762 is a TSSOP-16, and the 2408 is a SOIC-16.  And they are *tiny*.  Seriously.  My renewed interest in electronics and the Arduino spurred me on to research whether hand soldering was even possible with these parts, and I was pleased to discover that not only is it possible, it’s really quite easy as long as you use decent tools and follow a few simple guidelines.

Continue reading Don’t Be Afraid of Surface Mount Components!

Hacking Eaton HomeHeartbeat Part 4: Why Bother?

It’s been asked. Why bother? Seriously? HomeHeartbeat was hot sh*t back in 2005, but isn’t it showing it’s age now?

All valid questions. Consider this, however – let’s say, for the sake of argument, that you were just now getting into home automation. You really like the idea of building up a dataset of what’s happening in your house – how often doors are left open, lights are left on, etc. You want to make sure that lights are never left on in unoccupied rooms; you have a feeling that this happens a lot, but you really don’t have any proof. Say you want to know just how hot your attic gets in the summer, and whether or not that is a contributing factor to why the upstairs of your house feels like a bloody toaster in August. Continue reading Hacking Eaton HomeHeartbeat Part 4: Why Bother?

Book Review: Getting Started with the Internet of Things

I rarely write up book reviews except in extreme cases.  I admit that I am a harsh critic; rarely do I find a book worthy of praise, and when I do my reviews tend towards being large volumes in and of themselves.  This is a good thing – writing a book is a massive undertaking and I have a great amount of respect for anyone who undertakes the task.  Which is why I find it so frustrating when I find a book that is just plain bad.  I just can’t understand why someone would put themselves through the tedium and all of the work involved with writing and publishing a mediocre (or worse) book.

I really, really wanted to like this book.  It’s been talked up for months now, and while I don’t usually fall for hype, I admit to having high expectations for [amazon_link id=”1449393578″ target=”_blank” container=”” container_class=”” ]Getting Started with the Internet of Things[/amazon_link] from the folks at Make:Projects.

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Robust 1-Wire Support for Arduino via EDS HA7S


I have purchased several devices from Embedded Data Systems (EDS) over the last few years.  Their HA7Net Ethernet 1-Wire Host Adapter makes integrating 1-Wire devices utterly painless; it is a solidly constructed, well-engineered piece of hardware.  It is also very well supported by the OWFS project.  EDS is a pleasure to work with, their staff is knowledgeable, pleasant, and responsive.

I’ve got several remote areas that I would like to monitor using 1-Wire devices, and I’d like to use some of the more obscure 1-Wire devices which I’ve purchased over the years as well.  This seemed like an excellent use case for the [amazon_link id=”B004G4XVKC” target=”_blank” container=”” container_class=”” ]Arduino Fio[/amazon_link]: low power consumption, built in LIPO support, and [amazon_link id=”B004G4ZHK4″ target=”_blank” container=”” container_class=”” ]XBee[/amazon_link] support to boot.

A bit of googling turned up several examples for simple 1-Wire interfacing using the DS18B20, but very little in the way of other devices.  I would like to use some of the 1-Wire hardware that I have accumulated in this project – a dual channel counter, LCD board, and 8-channel relay board from HobbyBoards as well as various temperature and humidity sensors from iButtonLink.  Several of the pages I found referenced Peter Anderson’s 1-Wire interface adapter, which is a nice little design but does not support chaining devices and is limited to only seven 1-Wire devices.  There are a couple of other nice libraries available with more extensive device support as well, but I haven’t yet had time to dig into them.

Because I would like to support a larger number of devices on my 1-Wire bus, I don’t think direct control via Arduino is the correct approach; 1-Wire can be notoriously finicky when it comes to timing, and I just don’t want to invest that kind of time into testing and debugging.  Dallas Semi has created some very nice driver chips which would fit the bill nicely.  The DS2482S i2C to 1-Wire bridge and the DS2480B serial to 1-Wire bridge are both quite inexpensive and would be fairly straightforward to integrate with the Arduino; The only real drawback to these is the tiny SOIC-8 package and subsequent soldering difficulties. [edit: SOIC soldering really isn’t that difficult, as I recently discovered.  Read more here.]

While downloading a new firmware release for my EDS HA7Net I stumbled across the HA7S TTL 1-Wire Host Adapter SIP; it occurred to me that this is an absolutely perfect fit for my needs.  TTL level serial I/O, simple ASCII interface, extremely low power requirements, and very reasonably priced ($17 USD).  I’ve got two on order now, will blog more once I’ve received the devices and have had a chance to play with them.