Ultra low power timer

Thread Starter

cmartinez

Joined Jan 17, 2007
7,508
I need to build a timer capable of activating an output high signal in the voltage range of 3 to 5v, but I'd like it to consume as little power as possible, something in the range of less than 100 uA. Timing range should be adjustable between 30 minutes and 4 hours, which will start counting as soon as the device is turned on. Timing precision can be in the range of 5 to 30 seconds, so it's really not critical.

For this application, it's pretty obvious to me that an ordinary 555 is simply out of the question.
Where should I start?
 

MrChips

Joined Oct 2, 2009
24,600
But you still need an MCU to take advantage of the TPL5010.
Other options are to use something like standard CMOS logic such as CD4060 or a low power MCU. I am more familiar with TI MSP430G2553. Microchip PIC also has ultra low power MCUs.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,508
But you still need an MCU to take advantage of the TPL5010.
Other options are to use something like standard CMOS logic such as CD4060 or a low power MCU. I am more familiar with TI MSP430G2553. Microchip PIC also has ultra low power MCUs.
Yes, I'm aware of that... that's why I said I'd be back with more questions. Right now I'm working on the general aspects of this project.

I'm glad you've joined the conversation. I know that you're experienced in this sort of thing and your input is going to be invaluable. :)

Many thanks!
 

ebeowulf17

Joined Aug 12, 2014
3,282
But you still need an MCU to take advantage of the TPL5010.
Other options are to use something like standard CMOS logic such as CD4060 or a low power MCU. I am more familiar with TI MSP430G2553. Microchip PIC also has ultra low power MCUs.
The mcu at the heart of all of our machines is an MSP430xxxx and I find it quite frustrating that the IDE/compiler for it has an expensive annual license... we are mostly not an electronics or firmware company, so we don't have the license and have to pay a programmer who does have the license any time we want to change anything, no matter how trivial.

I don't know if this applies to the whole MSP430 line, and it may not be true anymore anyway (I've heard rumors that an open source solution is coming along,) but I'd be wary of starting a project with that chip unless you know you've got everything you need to work with it.
 

MrChips

Joined Oct 2, 2009
24,600
The mcu at the heart of all of our machines is an MSP430xxxx and I find it quite frustrating that the IDE/compiler for it has an expensive annual license... we are mostly not an electronics or firmware company, so we don't have the license and have to pay a programmer who does have the license any time we want to change anything, no matter how trivial.

I don't know if this applies to the whole MSP430 line, and it may not be true anymore anyway (I've heard rumors that an open source solution is coming along,) but I'd be wary of starting a project with that chip unless you know you've got everything you need to work with it.
I use IAR EW Evaluation License. You have two choices:
1) 30-day full version
2) 4k code limit.

So far, all my projects fall well under the 4k code limit.

Aside, as someone else posted, STM has taken over Atollic and is offering Atollic TrueSTUDIO for free.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,508
But you still need an MCU to take advantage of the TPL5010.
Other options are to use something like standard CMOS logic such as CD4060 or a low power MCU. I am more familiar with TI MSP430G2553. Microchip PIC also has ultra low power MCUs.
I've been browsing through several available architectures out there, and the one you're suggesting looks quite promising, using only 230 µA at 1 MHz, 2.2 V.

I'm also considering using a PIC10(L)F320/322. It boasts a power requirement of only 25µA @ 1 MHz, 1.8V... that's less than 10% of the power used by the TI chip! Maybe I'll even end up ditching the stand-alone timer and use one of this chips for all the functionality I need instead.
 

MrChips

Joined Oct 2, 2009
24,600
You can get power consumption below 1μA with little effort.

1) Use a low frequency Xtal, such as a 32768Hz clock crystal.
2) Use SLEEP mode to put the processor to sleep and wake up once a second (or longer) for time keeping.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,508
You can get power consumption below 1μA with little effort.

1) Use a low frequency Xtal, such as a 32768Hz clock crystal.
2) Use SLEEP mode to put the processor to sleep and wake up once a second (or longer) for time keeping.
I'm definitely going to consider that. Ease of programming is also a relevant factor. So far I'm only familiar with the 8051 architecture. So learning how to use the newly chosen MCU quickly is important.

Here's, in rough terms, what I want to do:

Using energy available from an air draft running through a pinwheel-like vane, I want to charge a supercapacitor that will power an MCU. The MCU will keep track of the time in which said draft got started, and trigger an output if that time is exceeded. This time will be preset within a range of 20 minutes to two hours. If, for some reason, the draft got interrupted before the preset amount of time was reached (and hence the vane stopped rotating for a moment), then the timing process will be reset and start over. But the supercapacitor must be kept on charging at all times using the power being delivered by the vane, which is coupled to a micro-generator.

When the set time has elapsed, the MCU's output will trigger a mosfet that will for a brief moment power a secondary circuit, using all of the energy available stored in the supercapacitor for this effect. The entire process will start all over again after this.
 

MrChips

Joined Oct 2, 2009
24,600
Personally, I don't get too hung up on which MCU to use. Programming should not be an issue since programming in C is standard across the board.
As they say, the best MCU is the one that gets the job done.

You will find that if you have two, three, or four, different MCUs (manufacturers) under your belt, you will be in a better informed position to choose appropriately for the next project. I have worked with perhaps at least six different makes and over a dozen different families of MCUs.

Every new chip you learn makes the next one easier.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
7,508
Programming should not be an issue since programming in C is standard across the board.
Not for me... regarding MCU's, I've done all my programming in assembly. And the last time I used C must've been about 25 years ago...

The reason is because all of my projects have been timing-critical, and each and every cycle performed by the MCU had to be accounted for.... but not this time, though...

I guess it's never too late to re-learn a language ;)
 

AnalogKid

Joined Aug 1, 2013
9,474
Another option is the CD4521. Similar to the 4060, but with a 24 bit counter for looooong delays. It has separate power pins for a very low power oscillator section.

ak
 

OBW0549

Joined Mar 2, 2015
3,566
Not for me... regarding MCU's, I've done all my programming in assembly. And the last time I used C must've been about 25 years ago...
That's about the way it's been with me, also. I took a course in C programming many years ago but have never used it other than when fooling around with an Arduino. For everything else, both at work and at play, I've done my programming in assembly language.

It's been my experience that what @MrChips said in post #14 applies very much to assembly language programming: every new chip you learn makes the next one easier. After a half-dozen or so, learning a new one becomes very easy.

One option you might consider is that some of the Microchip's PICs feature what they call an "ultra low-power wake-up" module which can wake the PIC up from Sleep Mode using an internal timer and an external capacitor. The 8-pin PIC12F683 is one part that I have used that has the ULPWU module, which is covered in Microchip's application note AN879.
 

danadak

Joined Mar 10, 2018
4,057
PSOC has low power capability, + analog + logic fabric + DSP + State Machine + routable + ....,
and tool/compiler is free.

http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide

Google "PSOC 101 videos" and watch a couple of the first lessons.

A list of components inside PSOC attached. A component is a resource inside
PSOC. PSOC 4 low end, 5LP and dual core 6 high end. Boards ranging from
$4, $10, $30.......Components are GUI drag and drop onto design canvas/schematic,
all accompanied by prewritten API calls.

PSOC low power -

http://www.cypress.com/documentatio...ing-low-power-and-estimating-battery-life-ble

http://www.cypress.com/documentatio...-psoc-5lp-low-power-modes-and-power-reduction

http://www.cypress.com/documentatio...-analog-coprocessor-low-power-modes-and-power


Regards, Dana.
 

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