Friday, September 30, 2011

"Nesting" Illustrated

How It Was:
I wanted to illustrate what I mean by "nesting" the connectors. This is not my preferred method of handling this problem, but if anyone out there has spare 10mm connectors and doesn't want to do any soldering/desoldering, it's a way to make the SparkFun protoshield work with their original ethernet shield. It's not optimal, but it works.


Here's a "tall" view of the the ethernet shield and the protoshield stacked on top of it. (By the way, the ethernet "shield" is the lower blue circuit board and the protoshield is the upper, red circuit board.) I put one pair (one 8 pin and one 6 pin) of connectors on the tails of the protoshield connectors, (It requires two pairs to be complete - I wanted to open only one pack of the parts I received.) You can see that NOW the bottom front edge of the protoboard, right under the two pushbuttons, easily clears the big metal boxed ethernet connector - by almost double the height of the ethernet connector!

You could, if you had to, nest to further heights - the bus speeds are not so fast that doing so would cause problems. Stacking shields like this works, and is a good temporary measure when you're trying to build something and need to get the idea proved out rather than worry about the details. But if you are building something that needs to last, it needs better mechanical and electrical connection - this trick just won't do for the long term. The leads can oxidize, lose spring tension, or "creep" due to heat/cold cycles.

New Arduino-format Solutions

These "shields" and the concept of stacking them are components of the "Arduino" concept.

Here's a comparison photo.

The microcontroller on the left is what I used in school - the big green PC board. The little blue PC board on the right is an Arduino. With some differences, the two microcontrollers essentially do the same stuff. Oh, except you can't program the big on in a high level language with an IDE like the Arduino. It's either machine language or a crude cross-compiler.

It's an "open microcontroller platform" intended for use by people who are not computer engineers by education, but are creative and desire to make things using a microcontroller. (but this doesn't stop computer engineers from using the platform....) There are two halves: hardware and software, to the whole, developed by brilliant professors and engineers. Their web presence is http://www.arduino.cc.

The hardware half consists of the base CPU (Atmel 8-bit 16Mhz processor with 14 digital I/O's and 6 analog I/O's), the basic CPU shield, a USB interface for both programming and power (or an onboard power connector - the system will automatically choose between the two), an FTDI port (if you can't use the USB for some reason or have a target board for the CPU that has no other control and programming I/O), and this PCB shape that has the two 6-pin headers on one side and the two 8-pin headers on the other side. There is an off-center gap between the headers on one side intended to act as a "key" to allow only "Arduino-format" products to be plugged into an Arduino base microprocessor.

The software half is the programming environment and bootloader - all pre-programmed into the processor. You don't have to install it yourself, it comes in the EEPROM of the CPU, making it ready for immediate programming with the host-side companion software for Windows, Linux and Mac. The part that runs on the PC is called the "IDE" - Integrated Development Environment.

It makes for an amazing and complete environment right at power-up. I was able to do in 30 minutes with an Arduino what it took a week or so to do back when I was in college. All I could think when I first used an Arduino was "Why didn't they have stuff like this when I was in school?!?!?" The complete set of hardware and software gives you the ability to DO things quickly, easily and without having to worry about voltage levels or timings of signals on the I/O pins of the shields. It totally frees your mind to embrace and push the creative process.

Options for Arduino/Atmel enthusiasts are changing rapidly for the better. I've previously mentioned the Freetronics protoshield that is shorter and made to clear the ethernet connector's metal "box". This is a simple, well-designed product that will be an improvement for many of you out there who are trying to keep your protoshield projects simple and easy.

Another new product from Freetronics: an ethernet shield with built-in prototyping area AND POE.. Wow, nice. That would have let me do this project with only the Arduino Deumilanove (now the Arduino Uno) and this board.

And another beautiful way to slice it would have been to get the new Freetronics EtherTen and pair that with the protoshield short.

Warning: NEITHER of these options are going to fit in the low-cost plastic enclosure. The ethernet connector is in the "wrong place" for both of these. You would have to stick with the stock Arduino, the stock ethernet shield MAYBE the protoshield short.

DISCLAIMER: I don't know the Freetronics guys, although I understand they are good blokes and know quite a bit about the Arduino and open source hardware.

Parts From Jameco

The parts from Jameco are finally here. Sheesh - when they meant 7-10 days shipping, they were not kidding. Exactly 2 weeks from order placement to having the box on my doorstep.


The materials arrived in perfect condition. They aren't the cheapest source on the 'net for parts, but Jameco does a good job when it comes to filling orders. Every type of component in it's own bag, all in one giant sealed bag. It's painful easy to inventory your order and you can do so without opening the small bags - so you can make sure everything's in order, and if not, easily send it back. Nice!


I immediately unpacked and checked the length of the tails on the new header connectors - 15mm, just as advertised. This weekend I should be able to get time to cut off and unsolder the stock headers. The little wise voice in my head says I should order the "Protoshield Short" from Freetronics as a backup in case I destroy this one trying to get things unsoldered. I think I'll make a first attempt on only one of the pins just to make sure I can do it before I go hacking and slashing, because I know I could simply "nest" a set of spare connectors under the protoshield to clear the ethernet jack, and keep on going. It would look terrible and probably not work worth a damn as a long-term solution, but it would work well enough to continue development.

Monday, September 19, 2011

Energy Monitor Highs and Lows

The current sensor just arrived from ITeadstudio. It is exactly the same 200A model mentioned by Dave

I am all ready to go with final assembly and coding of the prototype, when an old problem I'd forgotten all about reared it's ugly head: the prototype shield sold by SparkFun will not clear the ethernet shield, also sold by SparkFun. Arrrrgggg.

What's complicating this is the fact that I happily soldered-in the header connector components without checking the length of the "tails". Surely every shield they sell will mate to any other shield, right?

Wrong. The tails on the headers for the protoshield are 10mm long. You need 15mm long tails in order for the shield to clear the big RJ45 connector that sticks up high off the board and the 10mm tails won't clear it. But the 15 mm ones will. I have no clue why I didn't get 15mm ones on the protoshield - the fully assembled ethernet shield came with 15mm ones.

So I'm ordering replacement header connectors from Jameco and using solder wick to try to remove the headers I installed without damaging the board. If I can get the old, short ones out and clear the holes, then it'll be simple to install the new ones.

By the way: the Freetronics guys are doing it right. Check out their EtherTen for an Arduino with a built-in POE capable Ethernet interface, and the cool, compatible protoshield-short. Ahhhh. It's good to see an Arduino vendor with enthusiasm and energy to think about their products!

Stay tuned - a few days to get the new headers in and try the desoldering operation. I'll post photos, success.....OR failure!

Thursday, September 1, 2011

Enphase Micro Inverters

Check out this amazing product:

http://enphase.com/products/microinverters/m215/

It enables the build-out and operation of solar panels in the home environment using very simple, easy methods. You can expand from one-to-many panels without even having to buy the same panel, which is a serious problem for those of us who want to bild systems out a panel-at-a-time: many times panel producers will discontinue a product so they can introduce improved products. With the Enphase product, you can add that improved new panel to your solar array without problems.

Now, there are limitations and things to know about this product. So far, I've not been able to identify any way to use the product with batteries to perform a storage function for power outages, off-grid operation or overnight power supply. However, for ease of entry into generating your own home renewable energy, you can't beat the low cost, ease of use and flexibility of these modules.

More on the enphase micro-inverters later....

Did I mention Google Power Meter is dead? I mourn it's passing, but the Enphase folks provide the same kind of service to customers with their MicroInverter products, and the price is extremely reasonable, only a few dollars a year.

The High Holy Energy Conservation Season

In the US, September 1 marks the beginning of the Labor Day Holiday. While this is not a day of reverence as many holidays are, Labor Day marks the "official" end of summer and the beginning of fall. Daytime high temperatures begin to show signs of dropping off from the sweltering heat of the summertime. Nighttime temperatures drop such that people begin sleeping with their windows open and their air conditioning off. Harvesting of crops will begin in many areas, and the time of sunset in many southern locations has dropped by 1 hour at the end of the day (8:30pm local back to 7:30pm local).

In other words Labor Day it's a sign that the US winter heating season will soon be upon us and we must prepare - measure, insulate, conserve and take measures to blunt the energy and cost impact of the impending winter weather. You may want to wait another couple months before installing that temporary plastic wrap on your windows to gain your cold weather insulating layer, but it's definitely time to start measuring, planning, and assembling the components you need for your home energy projects.

Ironically, the months of September through November may be the months of lowest energy usage for many of you in the temperate zones of the US. Your air conditioning stays off, you don't need heat yet, and there's enough daylight that home lighting isn't a factor. This lulls us into a false sense of energy efficiency, and we don't get our conservation projects done until it's bitterly cold outside and we've already gotten that terrible power or gas bill.

Prepare, friends. Prepare now. Start measuring now. If you have been considering buying or making energy measurement equipment, do so now and get it installed as quickly as possible. This time represents a valuable time of "baseline data" you can use as you go into the winter months to determine how well you are doing and what you can do to more effectively save energy and money during the deeply cold months of winter.

New Stuff over at OpenEnergyMonitor

The gents over at OpenEnergyMonitor have taken the power and are making a difference. If you've not checked 'em out in awhile, they've changed their gateway web page to explain all the fantastic, creative technical things they've been up to!

http://openenergymonitor.org/emon/

These guys don't mess around. Check out their goodies!