Author Topic: A winter day in Moscow and a low power camera  (Read 12995 times)

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Offline Artlav

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A winter day in Moscow and a low power camera
« on: December 12, 2014, 08:32:57 pm »
An $20 JPEG camera, an $4 RF module, Atmega and some batteries.
Yesterday i've put them together into a little radio-controlled time lapse camera, and wanted to see how long the batteries will last.
So, it was left staring out of the window from 2:50 to 20:30 taking about 1 frame each 30 seconds.

The result happened to illustrate the mood of a winter day in Moscow.



The camera itself:




On 4 AAs it runs for about 30 hours, on 4 AAAs - 12 hours (extrapolating).

This got me thinking - have anyone made a camera for time-lapse photography, that would run from batteries for a few months (i.e. from a bunch of D cells)?
The idea is kind of to leave it be in a nice spot and come back next year, without worrying about getting power there.

Mine seem to be quite inefficient on that front, having to transmit the frames, and thus keeping the camera module on all the time.
But if you could somehow obtain a raw CCD chip, figure out how to make an FPGA standby at very low power, and store the frames onto an SD card...
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Offline Wilksey

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Re: A winter day in Moscow and a low power camera
« Reply #1 on: December 12, 2014, 09:15:41 pm »
Wow, you might think i'm weird for saying that looks quite nice lol, here in the UK that's a day off work! :)

What do the temperatures get down to in the winter in Moscow?
 

Offline Whales

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Re: A winter day in Moscow and a low power camera
« Reply #2 on: December 12, 2014, 09:41:35 pm »
Thanks for sharing the project and its footage -- it's very nice  :)

Despite the snow, would a small solar panel be possible?
Code: [Select]
4 cells * ~2.2 Ah * ~1.4V average = 12.32 Wh
12.32 Wh / 30 hour run = 0.41 watts on average

Something in the magnitude of a 160x160mm cell will do 4W.  Will cost a little bit and you will need a charging circuit + rechargeable cell.  I'm not sure how most rechargeable chemistries behave in sub-zero.

EDIT: Set it up under someone elses electric light with a smaller panel + supercapacitors so you don't need any batteries.


Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #3 on: December 12, 2014, 10:00:46 pm »
here in the UK that's a day off work! :)
Yeah, i heard about the "snowlidays" you like to have . :)

What do the temperatures get down to in the winter in Moscow?
The record this winter is still at -13*C.
Depends greatly on many things, really - can be -35*C in november, can be raining on New Year's day (while USA was freezing... Something broke, i guess).
But usually it does not get too far below -20*C, and most days are at warm -10*C-ish.

Despite the snow, would a small solar panel be possible?
Hm, if my solar powered weather station is to be believed, there wasn't a sunny day for two weeks already.
And, it wasn't getting enough sun for a net gain in battery charge since late October.
With only a month's worth of power in it's 2.8Ah Li-ion battery, that means i'll have to climb up there and change the battery soon.

That thing is a bunch of sensors and an RF module, even then it does not survive the winter on solar power.
A camera would do no better.

I'm not sure how most rechargeable chemistries behave in sub-zero.
Not great.
Quality li-ion can be charged at very low current down to about -20*C without immediate damage, but below that you only got supercaps and Lead Acid.

EDIT: Set it up under someone elses electric light with a smaller panel + supercapacitors so you don't need any batteries.
A wireless charger, hm? :)
Might not quite work on a roof, due to a lack of lights to seep from.
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Offline Whales

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Re: A winter day in Moscow and a low power camera
« Reply #4 on: December 12, 2014, 10:05:15 pm »
Perhaps you can find an aircraft warning beacon on a building  >:D

Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #5 on: December 12, 2014, 10:18:33 pm »
Perhaps you can find an aircraft warning beacon on a building  >:D
Hm.
I don't see any.  :-//
Do you?
http://orbides.1gb.ru/img/090315-pan-night.jpg
(Warning - 6Mb of panoramic view)
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Online IanB

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Re: A winter day in Moscow and a low power camera
« Reply #6 on: December 12, 2014, 10:49:19 pm »
But if you could somehow obtain a raw CCD chip, figure out how to make an FPGA standby at very low power, and store the frames onto an SD card...

Well, the system can sleep most of the time surely, and just wake up to take each picture? Does it need an FPGA to run it or can't it just use a microprocessor? Writing to an SD card doesn't seem hard. Plenty of battery powered monitor systems do that.

A typical pocket camera can take several hundred pictures on one charge and that is with all the overhead of the camera systems, LCD, backlight, and so on. It should be possible to beat that with a dedicated system and a bigger battery.
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Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #7 on: December 12, 2014, 11:32:42 pm »
Does it need an FPGA to run it or can't it just use a microprocessor?
I was under impression that it would take an FPGA to clock out data from a CCD chip?
Certainly not in Atmega's range of capabilities.

I've managed to scavenge a Sharp rj2361aa0ab chip (what it says on the back), and the closest datasheet i could find list frequencies in 10s of MHz.
Would need a fast ADC as well...

That, or i'm approaching it from the wrong end.

I tried to interface a linear CCD to an atmega, years ago, and it just does not seem to work at lower frequencies.
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Offline Wilksey

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Re: A winter day in Moscow and a low power camera
« Reply #8 on: December 13, 2014, 12:08:28 am »
Anything below 10 degrees here is considered "choppy", you go below 5, well, we are just not prepared for road conditioning.

The issue with snow is really the ice it compacts into, front wheel drive cars, lots of idiots and lorries!  Local driving is mostly OK, it's motorway / highway driving that seems to be flawed.

Anyway, cool project and time lapse!
 

Online IanB

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Re: A winter day in Moscow and a low power camera
« Reply #9 on: December 13, 2014, 12:54:10 am »
I was under impression that it would take an FPGA to clock out data from a CCD chip?
Certainly not in Atmega's range of capabilities.
I wasn't thinking so much of a bare CCD chip, I was thinking more of a complete camera module, such as the ones used in smartphones?
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Offline Psi

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Re: A winter day in Moscow and a low power camera
« Reply #10 on: December 13, 2014, 01:04:53 am »
You can get solar cells that do 0.5V @ 5A for like $4 each on ebay/aliexpress.  (or like $1 if you buy 20)
They are just the raw cells though, very thin, you need to protect them somehow.
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Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #11 on: December 13, 2014, 10:37:27 am »
I wasn't thinking so much of a bare CCD chip, I was thinking more of a complete camera module, such as the ones used in smartphones?
Might be a good idea, if i can find one.
However cell phone-sized cameras are terrible, optic-wise.
The view i shown was black with a touch of noise on one, while the 1/3 inch sensor in my UART camera gives a nice picture.

Then again, i'm curious at what would it take to interface one of these CCD chips.
If only i could get one with a datasheet...

You can get solar cells that do 0.5V @ 5A for like $4 each on ebay/aliexpress.  (or like $1 if you buy 20)
The lack of solar cells is not  the problem.
The lack of sun is.
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Offline jancumps

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Re: A winter day in Moscow and a low power camera
« Reply #12 on: December 13, 2014, 11:15:36 am »
Here's a summer photo I took late last June with the camera of my youngest.



Not electronics related but could not stop myself from posting ;)
 

Offline Yago

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Re: A winter day in Moscow and a low power camera
« Reply #13 on: December 13, 2014, 11:35:47 am »
Looks like a small wind turbine for charge would yield more than solar !
 

Offline jeremy

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Re: A winter day in Moscow and a low power camera
« Reply #14 on: December 13, 2014, 05:14:25 pm »
This used to be available: http://www.mathias-wilhelm.de/arduino/reviews/hacrocam/

It read out the data at something like 50MHz iirc from a sensor using just an ATXMEGA via DMA to an external SRAM. So I guess it is possible to do something like this using a microcontroller only. Perhaps you could just dump the image to an SRAM via FPGA, and then use a super low power micro to write it to the storage medium?
 

Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #15 on: December 13, 2014, 06:46:57 pm »
So I guess it is possible to do something like this using a microcontroller only. Perhaps you could just dump the image to an SRAM via FPGA, and then use a super low power micro to write it to the storage medium?
Actually, i did the math.
With some design changes i can make a camera that does 1 frame every 10 minutes for just under a year, on 8 alkaline D cells.
The limit is actually the 2 GB microSD card (if i won't bother with FAT32 support).

Big issue was the camera module, which used up 50mA even in power save mode.
With a P-FET above it, i can do a frame&write to microSD for 15 joules, or 90 joules per hour.
Add 1 joule/hour to ping the radio every 10 minutes and round off, that's 100 joules per hour.
A D cell stores about 60000 joules, and i need 4 of them to get the voltage.
So, 2 strings of 4 will give me about 200 days of runtime, in pessimistic estimate.

A box of batteries is cheaper than any renewables. :)

Etching the board already.
If it works, i might make an open source project out of it - a simple and cheap time lapse camera, capable of lasting for years might be interesting to people, no?

Looks like a small wind turbine for charge would yield more than solar !
Perhaps...
They are a pain to wind, however.
No pun intended.

Here's a summer photo I took late last June with the camera of my youngest.
Nice!
Tourism or relatives?

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Offline jancumps

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Re: A winter day in Moscow and a low power camera
« Reply #16 on: December 13, 2014, 07:14:54 pm »
...
Here's a summer photo I took late last June with the camera of my youngest.
Nice!
Tourism or relatives?
Work. Must have been there 30 times now. Also to Lipetsk and Lebedyan.
 

Offline jeremy

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Re: A winter day in Moscow and a low power camera
« Reply #17 on: December 13, 2014, 09:20:15 pm »
So I guess it is possible to do something like this using a microcontroller only. Perhaps you could just dump the image to an SRAM via FPGA, and then use a super low power micro to write it to the storage medium?
Actually, i did the math.
With some design changes i can make a camera that does 1 frame every 10 minutes for just under a year, on 8 alkaline D cells.
The limit is actually the 2 GB microSD card (if i won't bother with FAT32 support).

Big issue was the camera module, which used up 50mA even in power save mode.
With a P-FET above it, i can do a frame&write to microSD for 15 joules, or 90 joules per hour.
Add 1 joule/hour to ping the radio every 10 minutes and round off, that's 100 joules per hour.
A D cell stores about 60000 joules, and i need 4 of them to get the voltage.
So, 2 strings of 4 will give me about 200 days of runtime, in pessimistic estimate.

A box of batteries is cheaper than any renewables. :)

Etching the board already.
If it works, i might make an open source project out of it - a simple and cheap time lapse camera, capable of lasting for years might be interesting to people, no?

Of course! I would definitely be interested. Could just do a drive by card swap every few months to look at your pictures. Make sure you have decent mounting holes so that it can be put in a weatherproof enclosure.

What sensor are you using?
 

Offline dannyf

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Re: A winter day in Moscow and a low power camera
« Reply #18 on: December 13, 2014, 10:35:10 pm »
Quote
The result happened to illustrate the mood of a winter day in Moscow.

Nicely done. I am surprised that the sky lights up in no time - i am sure that's how it works everywhere but those pictures made it so "explosive".

BTW, what kind of neighborhood is that? Are those buildings recent or from the old times?
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Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #19 on: December 14, 2014, 12:16:28 am »
I am surprised that the sky lights up in no time - i am sure that's how it works everywhere but those pictures made it so "explosive".
Don't forget - it's 15 minutes per second, and the camera continuously adjusts brightness.

BTW, what kind of neighborhood is that? Are those buildings recent or from the old times?
An above average newly built residential area.
Recent, built around 2005.

Of course! I would definitely be interested. Could just do a drive by card swap every few months to look at your pictures. Make sure you have decent mounting holes so that it can be put in a weatherproof enclosure.
Enclosure is a given.
What i like doing are time lapses years long, showing the Earth moving around the sun, or an apartment block being built.
Or both: :)


For such things, you'd want to leave the camera be, at zero maintenance, outside, through a russian winter or two.

What sensor are you using?
A JPEG camera like http://www.ebay.com/itm/TTL-Interface-Camera-Module-CF0706C-V3-JPEG-CVBS-MCU-UART-/181550946094 , modded for 3.3V.
It's 640x480, with 1/3" sensor - good performance at night compared to cell phone ones or OV7670.
Averaging 48Kb per frame at max quality.


Ok, built a new board and tried it out.
It writes a picture to an SD card without problems.

Power, however, does not want to play nice - the theory and practice diverged a bit in what is being considered "sleep mode" by various parts.
Namely, the RF module does not want to play ball and go below 2mA, and microsd card sucks lots of current from MOSI line when it's VCC is out.
A redesign incoming, but the basic idea seem to work.
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Offline dannyf

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Re: A winter day in Moscow and a low power camera
« Reply #20 on: December 14, 2014, 12:30:02 am »
Wouldn't it be easier to just use an electronic trigger? That's how those high-altitude balloon guys do.
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Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #21 on: December 14, 2014, 12:37:16 am »
Wouldn't it be easier to just use an electronic trigger?
Hm?
Please clarify what this means.
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Offline dannyf

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Re: A winter day in Moscow and a low power camera
« Reply #22 on: December 14, 2014, 12:51:12 am »
Many cameras allow for shutter releases, both wired or wireless. Some are simple 2.5mm plugs, and others are fancier. You can simply plug the shutter release into the camera and then trigger it via your mcu periodically.

The balloon guys use this approach to take video / still images - early Canon's were popular with them. Google for more.
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Offline Artlav

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Re: A winter day in Moscow and a low power camera
« Reply #23 on: December 14, 2014, 12:54:57 am »
Power. A consumer camera will last hour on the batteries i plan for a year's worth of run time. Thats the whole point.
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Offline evb149

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Re: A winter day in Moscow and a low power camera
« Reply #24 on: December 14, 2014, 01:41:43 am »
You'd probably want to include a high efficiency SMPS buck converter to be able to take the initially too high voltage from a string of N cells and convert it to whatever your electronics need (3.3V, ...?) efficiently even until the cells are nearly 100% discharged at maybe 0.8V/cell or whatever the cell datasheet says.  There are some that can run at  100% duty cycle when the input voltage matches or passes under the regulated voltage level, and which take very low (microamp) level operating current and sub-microamp level disabled mode current.
Something very low power like a low power MSP430, STM32L, Kinetis KL would be a good wake-up timer chip for 1/10 minutes or whatever.  You could also program it to eliminate some of the night exposures if the camera won't be able to take useful pictures long after dark.

Assume any leakage currents will consume more power than you want, so you'd want to basically fully switch the power rails and any I/O connections to the deactivated circuitry away from a direct or indirect source of cell power.  There are bus transceivers that are rated for split power domain operation that have an "Ioff" leakage current specification and guarantee of HiZ inputs / outputs if the other side isn't powered.

Conexant makes a JPEG encoder chip and a couple of other vendors do also.  Some (VERY few) CMOS image sensors also include on-chip pseudo JPEG coding capability as well, but not SD card storage interfaces.  If you had a host with USB 2.0 high speed host capability, a fair many Webcam units have the circuitry included to deliver their images out in some kind of compressed format or other depending on whether it is snapshot, video, etc.  Some of the less expensive ARM CORTEX Ax series CPUs have camera interfaces and can support enough RAM to do JPEG encoding as well as have SD card interfaces on them, and of course there are SBCs for some of these chips -- BeagleBone, RaspberryPI, OOLINUXINO and some of the other Olimex SBCs and the Freescale MX series IC based ones may or may not depending on model have various levels of these capabilities.  Anyway there may be better power consumption vs. picture quality trade-offs to be had if you had more independent choice of the sensor and the image processor, so I mentioned various options.
As far as FPGAs go, I once figured out that the MachXO2 could interface to DRAM of some kind as well as a typical CMOS image sensor's parallel interface, and with some work you could probably do compression and SD card interfacing with it as well.  I think the MachXO2 and MachXO3 can also interface to some of the MIPI CSI bus types that are used in some of the newer camera modules that are used in newer cell phones, tablets, et. al.
Actually some of the CORTEX M4 NXP LPC parts with SGPIO and STM32F2/F4 parts can have / have parallel type cameras sensor interfaces, but they typically lack the RAM to do much processing of the data or even to hold a full VGA resolution frame, but they could work for QVGA, CIF, QCIF or some other approach but I'd use a CORTEX Ax SBC over the CORTEX M4 ones these days.

You might be able to find some inexpensive surplus laptop batteries that are good for this sort of environmental monitoring / sensing project since they're often discarded for old model laptops or when their capacity declines by 30% or something after a couple of hundred charge cycles.

Seems like you'd need much more than 2GBy SD card space for high quality photos with not too high compression but up to 32GBy is readily available if you change your mind.

 


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