Is anybody successfully running their project on coin cells? I'm finding that the low, low, low current the batteries deliver won't let me run a nano. I need a button and an LCD and enough memory to run 35K of code.
Anybody?
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Button cells like AG13 run toys with motors and coin cells like CR2030 run multimeters for ages.
Off topic a bit but I've used £1 power bank from pound land as a 5V supply just for pic supply.
They up the lithium cell to 5V. How can they sell for a quid? only 1200ma but B&M sell 2200ma ones for £2.
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I want coin cells for the size. I found out that at 10mA consumption, voltage drops through the floor, so unless I change chips, that's not going to work for me.
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There are periods of use where it would be nice to have the same thing on
the screen for up to an hour or two before I decide to go to sleep.
I just wanted to be sure that you are aware that e-paper only
requires power to update, not maintain the display, so taking your above
statement in top account there is no need to keep the CPU awake.
Spend a few mS updating the display then go to sleep or even better, power
down.
The displayed information will still be displayed even with no power to the
display.
Chris - good point! The only hesitation I have is that right now, I have a single button. I awaken with the push of a button, but during use, it depends on what kind of push (click, double-click, short hold, etc). The user knows it's asleep because the display is off, so intuitively, you know you're clicking to awaken. If the display is on, the user has no idea it's asleep. Right now, I wake everything up and reset to the top menu. Under your scenario, I'd have to respond to the type of command the user issues. I guess I have to see if I can recognize different types of pushes from sleep.
It's a great idea to extend the life of the batteries, I hope I can make that work.
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In sleep most modern microchip chips use only 1-3 uA. The probelm is the peripherals if you have a display (even an LCD) it can suck big time. The only way to get very low power is directly driving a 7-segment (i've got it down to 12 uA). The next best are Midas COG character displays which consume about 130uA and for a graphic display Displaytech 128x64 uses about 190 uA (depends how many pixels are active).
At one time I thought e-paper displays might be the way to go - well if you want to display the same thing for several hours using no power it is fine, but updating is slow and uses about 15mA.
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Thanks David. This particular LCD can be allegedly be shut down:
Write_Command_SSD1306(SSD1306_DISPLAYOFF)
We have a blizzard on the horizon for next week. I' will probably test the efficacy of that code then. I saw an e-paper display, and I was excited by its "low power consumption" claim until I got to the 15mA part. I didn't know that it can display the same thing for several hours and use no power. That's PERFECT for my application. There are periods of use where it would be nice to have the same thing on the screen for up to an hour or two before I decide to go to sleep.
I can probably live with slow writes. Thanks for the info.
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You can indeed turn the display off in software (or you could just power it through a pin on the microprocessor and switch that off - this would be advisable in a full power-down).
Either way the screen will go blank.
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That is the point of ePaper displays and battery powered devices.
Just to test my assertion I looked in my bottom desk draw and found a
Kindle Reader that has not be charged in over 6 years, the text and
Graphics are as clear as when I stuck it in there.
I'm in the process of making a battery powered device as I want the display to update regularly (every 16 sec) and for the display to be permanently on. So I have had to use 2xAA batteries (should last over a year) these have the advantge of cheapness and they give the feeling of quality from the added weight.
Is anybody successfully running their project on coin cells? I'm finding that the low, low, low current the batteries deliver won't let me run a nano. I need a button and an LCD and enough memory to run 35K of code.
Anybody?
Button cells like AG13 run toys with motors and coin cells like CR2030 run multimeters for ages.
Off topic a bit but I've used £1 power bank from pound land as a 5V supply just for pic supply.
They up the lithium cell to 5V. How can they sell for a quid? only 1200ma but B&M sell 2200ma ones for £2.
I want coin cells for the size. I found out that at 10mA consumption, voltage drops through the floor, so unless I change chips, that's not going to work for me.
You can get well small lipos like this. 3.7V 650mAH
yeah, actually, I found this, I'm going to try it: http://www.instructables.com/id/Cheap-LIR2032-Coin-Cell-Charger/' and if I can get it to work, I'll use rechargeable 2450's.
These constant current charger/supplys are cheap and useful for other things. Set volts to 4.2v for a 3.6V cell at 10th battery current capacity.
Is that the thing in the clear case? Where do you get one of those? Or is that what I bought? :-D
Looks like you built it.
Last edit: George Alvarez 2018-01-12
Hi George,
I just wanted to be sure that you are aware that e-paper only
requires power to update, not maintain the display, so taking your above
statement in top account there is no need to keep the CPU awake.
Spend a few mS updating the display then go to sleep or even better, power
down.
The displayed information will still be displayed even with no power to the
display.
Have a look at this web page:
http://www.electronicdesign.com/embedded-revolution/11-myths-about-e-paper-displays
Cheers
Chris
Chris,
Thanks for the info on e-paper displays. I wasn't aware of this technology till now. Sounds like opportunity for new applications of GCB.
BR
Mike
Chris - good point! The only hesitation I have is that right now, I have a single button. I awaken with the push of a button, but during use, it depends on what kind of push (click, double-click, short hold, etc). The user knows it's asleep because the display is off, so intuitively, you know you're clicking to awaken. If the display is on, the user has no idea it's asleep. Right now, I wake everything up and reset to the top menu. Under your scenario, I'd have to respond to the type of command the user issues. I guess I have to see if I can recognize different types of pushes from sleep.
It's a great idea to extend the life of the batteries, I hope I can make that work.
In sleep most modern microchip chips use only 1-3 uA. The probelm is the peripherals if you have a display (even an LCD) it can suck big time. The only way to get very low power is directly driving a 7-segment (i've got it down to 12 uA). The next best are Midas COG character displays which consume about 130uA and for a graphic display Displaytech 128x64 uses about 190 uA (depends how many pixels are active).
At one time I thought e-paper displays might be the way to go - well if you want to display the same thing for several hours using no power it is fine, but updating is slow and uses about 15mA.
Thanks David. This particular LCD can be allegedly be shut down:
Write_Command_SSD1306(SSD1306_DISPLAYOFF)We have a blizzard on the horizon for next week. I' will probably test the efficacy of that code then. I saw an e-paper display, and I was excited by its "low power consumption" claim until I got to the 15mA part. I didn't know that it can display the same thing for several hours and use no power. That's PERFECT for my application. There are periods of use where it would be nice to have the same thing on the screen for up to an hour or two before I decide to go to sleep.
I can probably live with slow writes. Thanks for the info.
You can indeed turn the display off in software (or you could just power it through a pin on the microprocessor and switch that off - this would be advisable in a full power-down).
Either way the screen will go blank.
Not if the Display is ePaper.
That is the point of ePaper displays and battery powered devices.
Just to test my assertion I looked in my bottom desk draw and found a
Kindle Reader that has not be charged in over 6 years, the text and
Graphics are as clear as when I stuck it in there.
Cheers
Chris
I'm in the process of making a battery powered device as I want the display to update regularly (every 16 sec) and for the display to be permanently on. So I have had to use 2xAA batteries (should last over a year) these have the advantge of cheapness and they give the feeling of quality from the added weight.