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Green Electronics


Casey Business Awards

We already let you know that we are finalists in 2 of the 9 categories for the City Of Casey inaugural Casey Business Awards in our post about being Casey Business Awards Finalists.The Casey Business Awards categories we are finalists in are: 

  • Manufacturer Of The Year
  • Business and Professional Services

The news has been picked up by one of our local Newspapers, The Journal, who ran the following article about us and the other finalists.  It is good to see so many strong contenders and our economy certainly needs strong businesses to continue to give both the employment and prosperity we have come to enjoy.  

The Journal - Successful Endeavours

The Journal - Successful Endeavours

 

Our congratulations go out to the other finalists and we will find out who the winners are on Friday 27th August at the Casey Business Awards gala dinner. 

It is good to see the Electronics Design, Embedded Software Development and Low Cost Electronics Manufacture featuring so strongly in the local Australian economy.  We especially note that Australian Solar Manufacturing is also a finalist in the Manufacturer of the Year category and we wish Jain and Janice Lal all the best with their nomination. 

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile. This post is Copyright  Successful Endeavours Pty Ltd.  

Electronics Design for Green Manufacture

This is not as straight forward a topic as it might at first seem to be.  And this is because there isn’t yet a unified agreement on exactly what Green Manufacture means.  And like most Design Issues, you cannot do Electronics Design without clear requirements.  So what are the requirements?

Here are some Green Manufacture requirements or targets:

  • reduce product Power Consumption
  • reduce manufacturing Power Consumption
  • add Renewable Energy options to the product
  • add Renewable Energy options to the manufacture process
  • reduce pollution or waste in the manufacture process
  • reduce energy involved in upstream or downstream processes
  • reduce pollution or waste in the upstream or downstream processes
  • increase product life
  • increase product utility
  • increase manufacturing plant utilisation

I guess you can see the dilemma.  It can be hard to know which target to aim for.  Am I doing the Electronics Design with the product, process, life cycle or ecosystem issues as the primary concern?  And how do I balance these concerns?

Here is one excellent article that also discusses this topic Green Supply Line.

Electronics Design can be Green

One major thing we can do is reduce the product Power Consumption.  We are coming out of a phase where a mains plug pack power supply was considered an ideal way to avoid compliance costs when designing new products.  This has led to a proliferation of low efficiency always on powered devices.  A recent look under my desk reveals the problem we have as Product Developers where every device I use is either USB Powered or mains plug pack powered.

So a first step is to review this whole approach to supplying power to devices.  We have made steady gains in the area of Power Consumption reduction for the devices themselves.  Now it is time to do a similar thing on the Power Supply side.

Energy Harvesting

This is a new area that hasn’t yet reached mainstream development.  The idea is that you can utilise the ambient environment to get power for free.  Or at least you aren’t directly requiring extra Power Generation.  Hence the name, Energy Harvesting.

How you do it and the Electronics Design and Electronics Technology required to make it work are still being defined but there has been some interesting new progress.  Some key players are:

Linear Technology – new Energy Harvesting Integrated Circuit

Enocean – are front runners in bringing Self Powered Wireless devices to the market

What is Energy Harvesting?

This is where we use Electronics Design and Electronics Devices to generate power from the Ambient Environment.  The result is a product that doesn’t need to be plugged in and recharges itself automatically. Some of the Energy Sources that are used are:

  • Light
  • Thermal differentials
  • Vibration
  • Chemistry
  • Pressure differentials
  • Air Flow

One example of a product that does this is the Enocean Light Switch where you can just put it where you want it.  And if you change your mind, just move it. Now wiring required.

Right now the technology is still more expensive and so take up is slow.  But as it develops and the price comes down that will change.

We are in for some interesting times.

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years. For more information go to his LinkedIn profile. This post is Copyright  Successful Endeavours Pty Ltd.

Electronics Design To Save Energy

We have looked at how Low Power Electronics is a green strategy because it reduces the amount of power that has to be generated.  And then we looked at a range of options for Reducing Electronics Power Consumption.

Now we are into specifics.  The last post looked at Sleep Modes For Microcontrollers and how extending the Sleep Period and reducing the Sleep Current could dramatically Reduce Electronics Power Consumption.

Saving Electronics Power When Awake

The next logical step is to ensure that Power Consumption when awake is also reduced as much as possible.  This can be a little tricky to get right as it can sometimes eliminate all the benefits you built up with you sleep strategy.  The reasons for this are:

  • you can use Analogue Electronics to reduce software power requirements but it has to be turned off during Sleep Mode
  • if you do turn the power off to Analogue Electronics then there is a Settling Time after it is powered up
  • using Smart Electronics Chips can increase overall Quiescent Current
  • unless the Startup Time and Shutdown Time are quick, these can dominate the Power Consumption

Now there are some Software Architecture issues that affect these, especially the last one, but we will look at that in another post.  For the last part of this post we will address the Electronics Design issues that have been raised here.

Electronics Design – To Save Power

Electronics Design can address these Power Consumption issues.  Here is an example of a Power Consumption curve where an RC Time Constant must be taken into account to minimise average Power Consumption.

RC Time Constant affect Power Consumption

RC Time Constant affect Power Consumption

Here is a list of general strategies to select from to reduce Power Consumption:

  • using the lowest feasible Clock Rate so Clocked Devices use less power
  • using shorter Settling Times particularly by controlling RC Time Constants
  • select semiconductors for lowest overall Quiescent Current taking awake and sleep operation into account
  • ensure streamlined Startup and Shutdown operation

The overall Quiescent Current issues often gives the most difficulty.  This can be addressed through Design Simulation either by SPICE, Software Modelling or a spreadsheet.  For simpler systems the spreadsheet is often the easiest solution to implement.  For very Software Intensive Systems the Software Modelling approach is the most reliable method.  This will allow you to construct scenarios and be able to predict the Power Consumption implications for each of them.

For our Electronics Design and System Test methodology we often create a full system Software Model and so it is easy to use this same Software Model to accumulate the power consumption as it runs.  This can also be automated and so simulate months of operation very quickly.

Next we will look at the role of Embedded Software in ensuring Power Consumption remains as low as possible.

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile. This post is Copyright © Successful Endeavours Pty Ltd.

How Does Sleep Save Energy?

For this post, we will look specifically at Embedded Software techniques to save power and energy.  This is a well known Power Saving Strategy which doesn’t always get the recognition it deserves.  It is also something you have to design into the Power Management Plan from the beggining.

For this example, we will use the MSP430 from TI which has some of the best Power Saving and Power Consumption figures in the industry.  We have used them to create devices that run from a pair of AAA batteries for 2 years and which have time based control algorithms so that they can’tbe used in a purely event driven mode.  Here is how it works:

Low Power Sleep Mode

Low Power Sleep Mode

This shows the power consumption versus time.  In Low Power Sleep Mode the consumption is close to zero.  Almost no power consumed.  Then depending on what is happening it wakes up to varying degrees.

Get the best Electronic Sleep

So this is how you take advantage of this:

  • make the time between wake ups as long as possible
  • make the time awake as short as possible
  • only turn on the peripherals needs for a particular wake period

Now if you system only has to wake once every minute then you can get low power operation from a lot of different processors.  If it wakes many times a second then you need a processor that gives you lots of ways to reduce power during wake, reduce the time awake, and increase the interval between wakes.

MSP430 Sleep

So back to the MSP430. It has Power Conservation features that allow it to do all three better than most.  Here is the list:

  • Digitally Controlled Oscillator DCO allows it to wake and run quickly
  • Can run a Timer from a 32KHz crystal making interval timing very low power
  • Can use the DCO to set the run speed and so shorten the wake time
  • Lot’s of Power Down Modes so you can always find one that suits your application
  • Peripherals can be Shut Down when not in use
  • Can run down to 1.8V – more on that later but it can also help here

Low Power System Architecture

To take advantage of all this, you have to develop the System Architecture so that  takes advantage of this.  An example from a very long life application we did runs like this:

  • 32Hz Oscillator runs a timer that generates a 1 second wake
  • User input keys set up to wake on change of state from high to low
  • Use DCO at 1MHz to quickly wake, execute & sleep again
  • Use State Machines to allow modules to execute predictably with eratic timing
  • Have early exit tests to prevent unnecessary Code Execution

The result is an application that runs a process with User Interaction, LED Indicators, and a 2 week cycle where the average Power Consumption is 20uA at 2.7V or 54uW.  Of this, less than half is the processor executing the software and the single biggest energy use is the intermittently flashed LED Indicators.

To learn more, check out this more comprehensive article on “Low power MCU selection criteria and sleep mode implementation” from embedded.com which provides more examples.

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile. This post is Copyright © Successful Endeavours Pty Ltd.