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Power consumption: a590 measurements and waveforms.

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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #10 on: 07 / July / 2009, 23:29:54 »
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Okay, here's the next set comparing various schemes for saving power, turning off the backlight is not that useful.


executive summary
Edit: See http://chdk.setepontos.com/index.php/topic,3872.msg36535.html#msg36535 for updated table


Notes:  Script turn off display was about the same as cam's idle mode, my test script's two second cycle time was a little fast for the DPO measurement.  

See the pictures and full story on http://bugsplatter.id.au/chdk/a590-power-2.html

Test script: http://bugsplatter.id.au/chdk/archive/lcdpower-2009-07-08a.bas.txt

Code: [Select]
@title lcdpower

@param a Test Number n 1-9

print "Press 'Shoot' to exit"
sleep 300
print " while display is on."
sleep 300

if a = 2 then goto "test2"
if a = 3 then goto "test3"
if a = 4 then goto "test4"

:test1
print "Test 1) set_backlight"
do
  set_backlight 1
  sleep 2000
  set_backlight 0
  sleep 2000
until 0 = 1

:test2
print "Test 2) Click 'display'"
do
  click "display"
  sleep 2000
until 0 = 1

:test3
:test4

end

:restore
rem 'shoot_full' trap
set_backlight 1
click "shoot_half"
sleep 400
print "Press 'set' to exit..."
wait_click 6000
is_key k "set"
if k > 0 then end
shut_down
sleep 3000
end
« Last Edit: 09 / July / 2009, 00:44:53 by bugsplatter »
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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #11 on: 08 / July / 2009, 02:10:56 »
Some more numbers - power vs battery voltage

        Record Active     Record  Idle        Record Active
        -------------     ------------        -------------
 V       mA      mW        mA      mW         CHDK Batt mV
----    ----    ----      ----    ----        ----
3.3      374    1234       109     359        3232
3.2      388    1242       112     360          -
3.1       -       -        117     363          -
3.0      414    1242       121     364        2930
2.9      432    1253       126     364          -
2.8      446    1249       131     366          -
2.7      466    1258       136     367        2635
2.6      486    1259       142     368          -
2.5       -       -        147     368        2437
2.4      530    1272       154     371        2339
2.3      556    1279       161     370        2254
2.2      580    1276       169     371        2140
2.1       -       -         -       -         2047

Note: these are raw numbers, no spreadsheet here to do the corrections for shunt + wiring V drop, I'll adjust the web page after download/install openoffice and adjust / interpolate the figures to fill the table. 
« Last Edit: 08 / July / 2009, 02:14:59 by bugsplatter »
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Offline fudgey

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Re: Power consumption: a590 measurements and waveforms.
« Reply #12 on: 08 / July / 2009, 03:55:48 »
I have now tried my a570is with and without CHDK on an old pair of 2700 mAh NiMH cells (fully charged a few weeks ago). The test was quick, only a couple dozen power cycles in total, but I think it was enough to get results.

The camera always starts to play mode and works perfectly while in play mode, with or without CHDK.

CHDK autoloading activated, camera only once powered on to REC mode without demanding to replace batteries and even then it immediately powred off when I half shooted. Same result from switching from PLAY to REC while CHDK is active (no matter if it was autoloaded or manually started); mostly it shut down right after switching, but once it let me press half shoot and then shut down. It always shuts down cleanly with the change batteries message.

CHDK disabled, the camera always starts to REC mode and also switches properly to REC from PLAY, and allows me to shoot successfully. It does blink the battery icon, but all in all it works.


Tampering with the battery test part of the firmware has been discussed before... many have doubts about safety, but IMO it now seems that there are two modes of operation and we're ending up with the wrong, trigger happy version meant for protecting firmware updates only meaning switching to the regular one can't be harmful if a way to do that is found.
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Offline fudgey

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Re: Power consumption: a590 measurements and waveforms.
« Reply #13 on: 08 / July / 2009, 16:54:10 »
Oh and since you're being delightfully thorough, there's one more thing missing unless your camera is different from mine: play mode input power with lens out differs from input power with lens in on my a570 (0.654 W vs. 0.526 W @ 3.15 V input), this is of course with backlight and display enabled, without av plug.



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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #14 on: 08 / July / 2009, 18:30:22 »
Quote from: fudgey on 08 / July / 2009, 16:54:10
Oh and since you're being delightfully thorough, there's one more thing missing unless your camera is different from mine: play mode input power with lens out differs from input power with lens in on my a570 (0.654 W vs. 0.526 W @ 3.15 V input), this is of course with backlight and display enabled, without av plug.

Thanks :)  I'm taking requests while I have the DPO on loan, so ask for anything that will clarify / extend our collective knowledge for CHDK now.  I'm trying to provide hard data because there's much confusion in some of the long interval threads about best power saving methods. 

I think I've noticed what your're saying here, but not followed it up.  I'm forgetful, and easily distracted so I miss stuff or forget to go back and check anomalies.

Other thing is I'm including mW because you do, but battery life is a tad more complex as batteries are rated in AH, not WH.  And AH depends on load (SLAs rated at their 20 hour rate, for example), temp and stuff. 

Couple more little observations I wrote down but didn't put up here:

a) CHDK Batt mV displayed value seems to have a constant slope integrating filter the takes about 10 seconds to reach a step-changed battery value.  Dunno if that filter is in CHDK or the cam, but I noticed the camera operates on actual battery voltage for low-going event triggers (for example on the last picture of second measurement set when camera activated lens park and power down as soon as Batt V went below 2.0V ), not the displayed mV value.

b) Once low battery state is detected by the camera, it stays in lobatt state (flashing red icon) until power is cycled even when the voltage is increased again.

c) Going too low on battery voltage, the cam will shutdown without pulling lens, seems if it decides there's not enough power to complete the operation it's safer to leave the lens out.

d) Taking the battery voltage down very slowly, I could keep the camera active down to 1.9V, it seems the cam also uses a derivative (rate of change) value for determining when batteries near end of life.  This one makes sense too if you consider that as battery capacity nears end, voltage drop and camera's current demand increases, thus pulling battery voltage even lower, faster, near end of battery life.
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Offline peabody

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Re: Power consumption: a590 measurements and waveforms.
« Reply #15 on: 08 / July / 2009, 19:36:47 »
Did we have values for using an AV plug in record/active mode?  So, in intervalometer, using manual focus, how much do you benefit from putting a plug in the AV port versus leaving the display visible?
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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #16 on: 08 / July / 2009, 21:36:36 »
Quote from: peabody on 08 / July / 2009, 19:36:47
Did we have values for using an AV plug in record/active mode?  So, in intervalometer, using manual focus, how much do you benefit from putting a plug in the AV port versus leaving the display visible?

We do now :)


Camera mode, operation                          V      mA      mW
--------------------------------------------  ----    ----    ----
Record active, MF mode                         2.5     584    1460
Record active, MF mode with AV lead in          "      530    1339
Record active, MF mode, backlight off           "      502    1255
Record active, AF mode                          "      504    1260
Record active, AF mode with AV lead in          "      448    1120
Record active, AF mode, backlight off           "      420    1050

Record idle, MF mode, camera idle              2.5     148     371
Record idle, AF mode, camera idle               "      147     366
Record idle, AF mode, script idle               "      138     345

Play mode, lens extended (AF or MF mode)       2.5     236     590
Play mode, lens retracted                       "      184     461

USB sense current, 5V to USB power via 200R            400uA

Note: Record Idle measurement is quite noisy and takes some time to settle, I imagine this is due to thermal effects as the CCD is off and camera innards are cooling down.  I'm inclined to average this group of measurements and take them as being the same, as the differences here are very near or within the measurement noise.  I need to perform a much longer term measurement sequence to reflect real world power use.  Now if only a590 had LED control...

Updated measurements on 2009-07-09
« Last Edit: 09 / July / 2009, 08:36:40 by bugsplatter »
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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #17 on: 09 / July / 2009, 01:16:30 »
Another annoying effect I've noticed is that the camera uses more power after it warms up :(  Just switching on cam now and repeating some tests, plus new ones, the values for modes I'd measured before were 3% lower, for example 1056mW for active record lcd_backlight off vs 1090mW yesterday, a 3% drop.

I'd noticed this variation earlier but not paid much attention, other than to mentally mark the measurements as having 2 or 3% uncertainty -- which I think is okay, but should be kept in mind since it's winter here down under and summer for those of you up the other hemisphere ;)

The new effect I noticed is that scripting lcd_backlight off saves about 5.4% (MF mode), or 6.8% (AF mode) power compared to stuffing in an AV (dummy) plug, with the benefit you can still read the screen under a strong light.

I also adjusted the test script to have an @param control for dwell, these latest measurements taken with a 5s dwell instead of the 2s used yesterday.  Maybe a new all-warmed-up measurement sequence later.  
« Last Edit: 09 / July / 2009, 06:52:01 by bugsplatter »
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Offline Microfunguy

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Re: Power consumption: a590 measurements and waveforms.
« Reply #18 on: 09 / July / 2009, 05:46:09 »
Quote from: bugsplatter on 07 / July / 2009, 23:29:54
my test script's two second cycle time was a little fast for the DPO measurement.  


Hmmm  .... and that is a very expensive 'scope.

Can you recommend any less expensive digital or USB 'scopes ?
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Offline bugsplatter

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Re: Power consumption: a590 measurements and waveforms.
« Reply #19 on: 09 / July / 2009, 06:46:29 »
Quote from: Microfunguy on 09 / July / 2009, 05:46:09
Quote from: bugsplatter on 07 / July / 2009, 23:29:54
my test script's two second cycle time was a little fast for the DPO measurement. 

Hmmm  .... and that is a very expensive 'scope.

Can you recommend any less expensive digital or USB 'scopes ?

Was easier to get an accurate reading on a five second cycle, I could have use the cursors to define a point or small range and measure -- funny, the DPO is geared to taking far more complex measurements (all sorts of phase, overshoot, undershoot, even an FFT module), the simple measurements are not covered that well -- but I've not read the user's manual yet -- 'cos big boys don't read the manual until they're really stuck 8).

I've looked at USB connected 'scope frontends and they're quite expensive even for dismal performance, plus there's a premium for the PC 'scope software.  I'm lucky to be able to borrow this instrument. 

For me it would possibly be a USB connected thingy like the Arduino boards -- cheap but configurable and free access to design info and software.  Or buy a serial connected DVM?  They're relatively cheap too.  Depends so much on budget and requirements.
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