Successful Endeavours - Electronics Designs That Work!

Global Warming

Battery Technology

Batteries have come a long way. There are still a lot of things we can do with existing technologies and this was covered in Making Batteries Better.

Lithium Ion Battery

The leading Rechargeable Battery Technology at present is the Lithium Ion Battery because of the high energy density and reduced weight compared to Lead Acid Battery technology. But there is a problem with them wanting to explode so a lot of care is required in both making and using the Lithium Ion Batteries. And there are different types suited to different applications including non-rechargeable Primary Cell application.

Sodium Ion Battery

An emerging Battery Technology is the Sodium Ion battery. And it has a number of advantages.

Sodium Ion Battery Pack

Sodium Ion Battery Pack

The advantages it brings to the table are:

  • not a rare material like Lithium
  • much more stable
  • can be charged faster
  • can deliver higher discharge currents
  • are able to supply the same voltage range (around 3.6V)
  • will be cheaper to make, and use, and recycle

The idea has been around since the 1970s but took a back seat to Lithium Ion Battery technology. Now Sodium Ion Battery technology it is coming to the fore and key researchers in Australia are helping to make that happen. The diagram below shows how it works. Click on the diagram for a full sized view.

Sodium Ion Battery Chemistry

This schematic illustrates the functioning of sodium-ion batteries. The high cost and scarcity of lithium are driving research to develop alternatives to lithium-ion batteries, especially to meet future needs in energy storage. One potential alternative is sodium-ion batteries. (Purdue University image/Vilas Pol)

Some further reading for those interested:

Better and more affordable batteries will be one aspect of adding storage to the Electrical Grid and make renewables more viable for base load demand satisfaction.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In AustraliaRay Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2018 Successful Endeavours Pty Ltd.

Electrical Power Distribution

Electricity is essential to the modern world. It is the power source behind the vast majority of modern appliances. And for large quantities of it, we are currently mostly burning things to produce heat to run generators to create AC power to transformers to high voltage power lines to more transformers, low voltage power lines and eventually, homes, businesses and facilities.

AC power distribution has become the dominant way power is distributed because it was easier and more reliable to make big transformers than do DC/DC power conversion. And to reduce heat losses in wires higher voltages at lower currents is a good strategy. This is Electrical Engineering 101 material.

Today however, this has changed. DC/DC power conversion is now routinely used at high voltages and is more efficient than a transformer. So that saves some of the burning which helps reduce carbon emissions and can help with a range of concerns from climate change to pollution.

A good example of this is Basslink which passes power from Tasmania to Victoria at 400kVDC. While there is some criticism that it doesn’t deliver the originally planned 630MW (only goes to 500MW) it is still a good example of this type of technology.

Reducing Losses

There are other options for reducing losses and Power Factor Correction is one of the primary ones. This process add leading power factor capacitive reactance to the distribution grid by putting capacitors in to correct for lagging current due to lagging power factor inductive reactance from the dominant loads in the system such as motors etc. A good example of products that manage this are the ABB CQ900 and CQ930 smart power controllers. Both Australian design and made products. These are networked and Smart Grid enabled.

ABB CQ900R Smart Controller

ABB CQ900R Smart Controller

The other strategy is reduces losses at the loads. So LED lighting, building management systems, better insulation and better business models that make it worth the while of the asset developers to consider the long term energy footprint of running the asset. This is covered very will in Natural Capitalism.

Natural Capitalism

Natural Capitalism

Improving Distribution

In Electricity Grid 2.0 and Global Power Grid we explored what a world electricity grid could look like if we started again now. And High Voltage Direct Current plays a key role as do renewables and storage. However, if it really is a world grid then the sun will always be shining somewhere and when it is winter here is is summer elsewhere so a lot of the issues with variability can be averaged out.


Improving Load Management

Companies like Rectifier Technologies Pacific design and make higher efficiency power supplies for backup power, uninterruptible power supplies and data centers. This is an important way to reduce power losses. It also won them some iAwards.

Rectifier Technologies Pacific

Rectifier Technologies Pacific


Another approach is to micromanage the AC power itself and this is being done by companies like 3DFS that are putting microsecond level load demand management into data centers. They call is Software Defined Electricity. and it works by cleaning up the fluctuating demand distortion of the AC sine wave our Power Distribution Network is meant to be delivering.

3DFS Cleaning Up AC Power

3DFS Cleaning Up AC Power

They have some very advanced ideas on how to go about this and already have products in the market. You can get a good understanding of their overall strategy from the video below.

An even more interesting idea is that of making devices smarter so they work with the grid to manage their own demand so the total process is more efficient overall.

And finally, Low Power Electronics devices can reduce the amount of power needed to achieve a function. Some of the technologies we are working with now allow up to reduce power consumption by 3 orders of magnitude.

So there are lots of ways we can do it better and if we work together and use all the tools available to us then it is likely we will succeed at achieving that. The place to start is knowing it is possible.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In AustraliaRay Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2018 Successful Endeavours Pty Ltd.

Electric Vehicles

This is a post I started 6 years ago and decided not to publish. Since then things have changed a lot so here goes.

The History of Electric Vehicles

The Electric Vehicle has been around for a long time. The new push to Electric Vehicles is mostly being pushed by the belief that they will reduce carbon emissions. This really depends on where the power comes from, how efficient the motors are and how well the batteries work. Most studies prior to 2011 have shown that unless a substantial amount of the power comes from renewable energy then it is likely the Electric Vehicle will generate more pollution than a petrol vehicle.

Electric Vehicles began a long time before the petrol vehicle was the norm and even way before Vanguard made the first mass produced Electric Vehicle in the 1970s.

Vanguard-Sebring Electric Vehicle

Vanguard-Sebring Electric Vehicle


Although details vary, 1828 is generally regarded as the date of the First Electric Vehicle and Anyos Jedlik put together a small scale model decades before the modern combusion engine cycle was invented. And the challenge was the same then as it is now, the battery. The History of Electric Vehicles is also the History of the Battery.

Jedlik Electric Car

Jedlik Electric Car

So what happened to the Electric Vehicle?  The challenge today is still the same, the Battery. We really need a better solution. Which is where my original post stopped.

Guess what? It seems to have happened.

Tesla et al

So enter Elon Musk and Tesla Motors. His purpose is to take petrol off the road so they have done some pretty innovative things including opening up their patent database so anyone can use their technology with their permission.



And of course Nissan, Toyota, Honda and many others are putting Electric Vehicles front a center in their product lines now.

With improvements in energy density storage and reducing costs for high capacity batteries we are approaching a time when Battery Electric Vehicles are the better choice for the environment, even when charged with electricity derived from fossil fuels. Studies show that there are more Emissions from the manufacture of a Electric Vehicle, but this is made up for in 1 year of operating emissions improvements and over the course of the Electric Vehicle’s life, Global Warming Emissions are halved. This assumes a 50mpg (US based study) petrol vehicle is used for the comparison. This equates to 21.3Kpl or 4.7L/100Km so this is as realistic comparison with a high efficiency petrol or diesel vehicle.

What a big different 6 years makes.

Hydrogen Fuel Cell Cars

So how are Hydrogen Fuel Cell based cars progressing? Calculations are that it will be roughly 3 times less efficient that a Battery Electric Vehicle. And extracting the H2 also requires energy. So H2 is an energy storage source. It is hard to store and manage and so the infrastructure costs are also high. So it is hard to do. The plus is that you don’t consume any fossil fuels in the process if you use some of the new solar based extraction mechanisms so although there are big drawbacks, there are also big benefits. The following video covers the territory well including some commentary from Elon Musk toward the end.

Let’s look at another perspective which is more optimistic.

So the infrastructure just isn’t there. So it looks like Battery Electric Vehicles are still the way to go. But the advantages are big enough that the debate will continue. And it is interesting that we have multiple fuel types in use simultaneously including Petrol (gasoline), Diesel, LPG, Alcohol, Battery Electric, Hydrogen, Biodiesel, compressed air, coal, wood and others.

The big advantages for Hydrogen are:

  • longer operating range than battery alone but not as much as petrol/diesel/LPG
  • no harmful emissions when running, the same as Battery Electric Vehicles and a big improvement over petrol/diesel/LPG

Time will tell. I should put a diary entry into my calendar for 6 years time and do another comparison.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In AustraliaRay Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2017 Successful Endeavours Pty Ltd.

LED Street Lighting

With concern for rising global emissions and the majority of the worlds power still generated by burning fuels of one kind of another, the replacement of older street lighting technologies with higher efficiency and longer life LED Street Lighting would appear to make sense. And on the up side, everyone agrees that the longer life of the LEDs compared to other lighting technologies is a huge plus.

However, it turns out to be not as simple as that. In LED Streetlights Are Giving Neighbourhoods the Blues the author, Jeff Hecht, points out a few other issues to consider. The picture below graphically demonstrates one of them.

Modern Street Lighting - Aerial View

Modern Street Lighting – Aerial View

Colour Temperature, or how warm or cold a light appears to our eyes, has a significant impact on how we perceive the lights. Above we see very white looking LED lighting alongside more traditional High Pressure Sodium lamps. The much bluer LED Street Lights cause several serious issues including:

  • actually reducing our ability to see clearly at night
  • disturbing noctural creatures more (eg. hatching turtles)
  • affecting sleep patterns
  • affecting biorythms
  • decreasing our ability to see stars at night

So the energy savings are real, but the environmental side affects are too.

Managing Colour Temperature

Unfortunately LEDs are not as easy to control for Colour Temperature. Unlike an incandescent light, they emit a very narrow band of wavelengths of light. And most White LEDs emit blue and use a phosphor to down convert some of the Blue to Yellow so they look whiter rather than Bluer. The earliest White LEDs were very blue and so early adopters of LED Street Lighting have ended up with the worst outcome. And the more we warm up the colour the lower the efficiency because we lose some energy in the down conversion.

The are some breakthrough underway and Cree have recently discovered that it is more efficient to add some red LEDs to the mix to drop the perceived colour temperature. And this is helping. But even the newest devices are at a colour temperature of 3000K and the High Pressure Sodium Lamps are at around 2100K. So still quite a bit different.

The only solution for the millions of already installed LED Street Lighting is unfortunately to swap them out for more recent LED arrays that are at a better colour temperature.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In Australia. Ray Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2016 Successful Endeavours Pty Ltd.

Local versus global electrical power

Up until recently, AC Power Distribution was the most efficient way to move electrical energy about. But right back at the beginning of electricity, it wasn’t obviously the case. Thomas Edison had favoured DC voltage and current distribution but was defeated commercially by almost all other comers because the technology to do AC Voltage Transformation, the transformer, was just easier top make than a DC version based on the technology of the day.

Thomas Edison

Thomas Edison

You can read more about this era in the War of Currents. This was the 1880’s of course. Probably the highest fundamental invention decade so far. But that is for another post.

Modern DC Power Distribution

Wind forward more than 100 years and the technology to transform DC voltage and current, at high efficiency, is mainstream. Of course the incumbent AC infrastructure is wide spread and not easily displaced. But DC is winning ground in new installations.

In Australia, Basslink is connecting Tasmanian power generators to the Victorian electricity grid using HV/DC or High Voltage DC Technology. It is now the technically superior offering.

World Power Grid

And so the new opportunities open up for sharing power across the globe. The current plans are just for grid connect. But if you consider renewable energy as a major contributor, if we have a globally connected grid then the solar power generators sun side can be supplying the night side communities and 12 hours later the other way around. If solar goes global and the grid goes global, then the fluctuating and time of day dependent power generation can be balanced out globally. What we can’t make economic in a single region, can suddenly become overwhelmingly compelling across the globe.

That will require quite a lot of collaboration and market trading beyond what has traditionally been possible, but the pay off would prove worth it. I am going ahead of what we can currently do, but I also believe this is where we have to get to.

Global Power Grid

Global Power Grid

For more information on the current state of play, check out the IEEE article on Let’s Build a Global Power Grid.

And you can be sure we will be doing all we can to support the push.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

Solar Cells

The primary Solar Cell material is silicon. It converts photons into electricity and the more efficient panels have a multi-layered construction.

Silicon Solar Cell Construction

Silicon Solar Cell Construction

But it isn’t only the construction that affects the efficiency. There are other factors such as:

  • Angle of Incidence of the incoming light
  • Photon Density in the silicon
  • reflections
  • shading

These can make a significant difference to the outcome. In 2012 we received the Electronics News Future Award for The Environment. This was for our work in developing the control systems and sensors for a Tracking Solar Array. This has greater efficiency because it addressed all 4 of the above factors at the same time. Here is how it did that.

Angle of Incidence

The Angle of Incidence is also referred to as the Cosine Effect. As the light comes into the panel from a more acute angle, the effective area of the panel reduces and so the energy to be converted also reduces. So this means that Solar Cells produce more electricity when the sun is immediately overhead and the production falls of before and after that. So if the panel follows the sun during the day keeping the sun overhead or normal to the panel, then the amount of energy converted and electricity produced increases. But how much?

Solar Tracking Efficiency Improvement

Solar Tracking Efficiency Improvement

The graph above shows the improvement in Solar Photo-Voltaic Electricity Production due to tracking the sun for either the entire day, from 45 degrees either side of midday or from 30 degrees either side of midday. Even just tracking 30 degrees either side of midday gives you 40% more electricity whereas tracking 45 degrees either side of midday produces nearly 60% more electricity. This on its own is more that the current trends in materials and panel construction are predicted to be able to achieve.

It wasn’t that long ago that a panel would not produce, in its lifetime, enough energy to recover the manufacturing energy it took to make the panel.  The past 20 years have seen advances that now reverse this and a properly manufactured and installed Solar Panel is a net energy producer.

So where do the other efficiency improvements come from?

Photon Density

The Technique Solar Module used Fresnel lenses to concentrate the sunlight into strips of 1/4 cut Solar Cells. There were 10 such strips. As a result, the Photon Density went up by a factor of 3. This not only allow less silicon to be used for the same amount of light, but it also increases the energy conversion efficiency. So the Solar Cells were getting a conversion efficiency above 40%. This is double the normal efficiency of higher grade Solar Panels.

The reduction in shading comes from having a smaller structure which can be positioned to maximise access to open sky.

Reflections off the inside of the individual strips were actually used to direct sunlight back onto the Solar Cells. And the cells were high grade with the best anti-reflection surface layers.

And the array was split into 2 sections using a Micro-Inverter on each section. Micro-Inverters are a topic for another day but they will have a big role to play in the overall move toward renewable energy at the residential and commercial level.

Concentrated Solar Panel Array

Concentrated Solar Panel Array

The array above is a linear solar array. There is a Sun Position Sensor at the center of the linear array and the array it rotates about the central axis. This is a different approach to the work we did for Solar Systems (now part of Silex)which was a Concentrated Dish Array that did 2D tracking as shown below.

Solar Systems Dish On Sun At Fosterville

Solar Systems Dish on sun at Fosterville

What is clear is that Solar Cells and Solar Photo-Voltaic energy conversion are here to stay and will continue to grow in importance for creating energy with reduces pollution in the future. Regardless of the individual views on Global Warming and Climate Change, reducing pollution is always going to be in all of our long term interests.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2013 Successful Endeavours Pty Ltd.

This post is a summary of an article I wrote for the latest AMTIL Australian Manufacturing Technology magazine which came out in print edition today and can also be read online.  Go to page 40.

And here is a picture taken of a Solar Systems concentrated Solar Power Dish. We were involved in software upgrades to the dish controller.  It produced 114KWhr of power on an August day at Fosterville, near Bendigo and this picture was taken on that day.

Solar Systems Dish on sun at Fosterville

Energy Storage

The biggest issue with electricity is that it is hard to store. The Electrical Grid delivers power on demand and manages the generators to maintain the frequency and voltage while delivering the required power to satisfy the demand. Quite a juggling act.  And while there are schemes like the Snowy Mountains Hydro where we can pump water uphill to consume power then let it flow downhills and run turbines to produce power, most power is managed at the generator directly.

Wind Power, Solar Photo Voltaic and Solar Concentrated are the primary renewable energy sources we will look at here, and they all provide a fluctuating supply.  You can’t easily crank them up or down with the demand. So we still need a base supply to do the balancing act.  Depending on our approach, it is estimated that the limit for these fluctuating supply types is between 8% and 30% of the total grid capacity.

Carbon Footprint

This represents how much carbon is releases into the atmosphere for a particular activity.  The top emitters of carbon are:

  • livestock, principally sheep and cattle
  • power generation
  • transport (road, rail, air, sea)
  • industrial processes
  • land clearing, deforestation and agriculture

In Australia, 50% of our emissions come from power generation as we use a lot of brown coal which also happens to be one of the most polluting ways to generate power on mass. This is followed closely by transport.  So you can see why power generation and transport are primary focuses for improving our carbon footprint.

There are only a few ways to improve this. These are:

  1. use less power – which creates the opportunity for more energy efficient devices to be created or alternative ways of doing things such as the use of smarter appliances that conserve energy use or even cooperate with the grid to use power at the best possible time
  2. reuse existing energy – heat exchangers in air conditioning systems are an example of this
  3. create energy in more efficient ways – new generator technologies or moving from dirtier sources to cleaner sources
  4. create energy in ways that does not use carbon, or uses a lot less of it

Because in Australia the creation of electricity is our primary source of greenhouse emissions we will focus on this area for the rest of the article.

Australia is ranked 5th in overall greenhouse gas emissions per capita and we are the highest per capita emitter of the industrialised nations so it is in our interest to develop alternatives to our current high emitting energy infrastructure.  This is also where some major manufacturing opportunities arise for Australian industries.

Australian Manufacturing Opportunities

One of the leading contributors to greenhouse gas emissions is sea freight. So the classic Australian model of digging it up, shipping it overseas and shipping value added goods or materials back is a poor strategy when you consider the greenhouse gases produced. There will be an increasing advantage of doing the value add locally when reducing the total carbon footprint becomes important.

Here are some examples of successful local manufacture of alternative energy products in Australia today.  This is a very cursory list:

  • Australian Solar Manufacturing is importing silicon cells and manufacturing complete TUV approved panels in Hallam, Victoria.
  • Solar Systems are world leaders in concentrated solar silicon photovoltaics and are putting together the world’s largest concentrated solar electric facility in Mildura.
  • Latronics and Solar Energy Australia both locally manufacture grid tied central inverters

Here are some opportunities to consider in the near future.  This is just scratching the surface:

  • BP Solar are working with the CSIRO on deep discharge lead acid batteries for use in energy storage for remote solar installations. This will lead to new battery technology and new manufacturing opportunities.
  • CSIRO are world leaders in organic photovoltaics and organic semiconductors. VICOSC is established to commercial the organic photovoltaics and there will be many opportunities that come from this initiative.
  • Existing mounting and installation hardware for photovoltaics is labour intensive to use. There are opportunities for smarter and more elegant systems to make installation more modular and straight forward. This can work with local or imported panels.
  • Most grid connected inverters are imported but there are concerns about both build quality and whether they are all compliant with Australian Standards.  The world market for inverters is set to grow by a factor of 10 over the next 5 years so there are also export opportunities.
  • Biofuels will become increasingly more important and there will be many opportunities related to this at both the production and consumption end of the process.

As you can see from the list, there are opportunities in both the core technology manufacture and also in the supporting systems and hardware.

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 at Ray Keefe. This post is Copyright © 2011  Successful Endeavours Pty Ltd.

Ross Brinsdon of Can-Tek

Ross Brinsdon of Can-Tek

We are so pleased to announce that Ross Brinsdon of Can-Tek has won the latest episode of the ABC program The New Inventors with his water based aerosol touch up paint product which allows you to get exactly the custom colour you want in an aerosol can that is loaded in store and is water based so you can clean it off before it dries if you make a mistake. And it is environmentally friendly as well.

The secret is in the chemistry added to the can that reduces the surface tension of water so the paint sprays and coats evenly.  This is a major challenge for water based paints and to be able to do it in store with the colour of your choice is a major advance in this area of technology.

We have had a couple of electronics products we worked on win on The New Inventors so we really appreciate the work it takes and that you don’t get these awards without having a serious advance.  You can also check out our Electronics Awards.

So well done Ross Brinsdon.  Keep up the good work.

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.

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 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.