Power consumption, sleep and wakeup issues

ansman · 12-10-2015, 05:10 AM

Edit: more details on my blog...
Servus,
I am working on a project where the Kindle DXG has to operate autonomously in the field. It will be powered by a battery pack, which lets say provide power for several weeks or a month or so. It will will idle most of the time and only wake up every 24h, turn on 3G and download a background image from a server and suspend again.

I know that my project is similar to the online-screensaver, but since the Kindle need to run from external battery the power consumption is big issue.

I run into several issues, and I dont know if they can be solved and/or what is the best solution to achieve my needs. Therefore I ask you to give some hints or suggestions. Below I will list these issues. The software I use is Kindle 2.5.8 on model B009 (dxg).

1) Power consumption: If I attach the DX to a 5V power source over the micro-USB, the kindle never falls into suspend and also consumes around 90mA. This is way to much as an idle current. (I did not tried to change the governor to 'powersave' yet, but expect not to change much.)
I read that

Code:

echo mem > /sys/power/state

is propably not the every thing the kindle does to suspend. What would be the proper command? Anyway, if I do that, the charging LED turns off and I loose USBnet connection. If I measure the current drawn when replug the USB: 1st second ~0.8mA, then 1-2 second long ~8mA and afterwards 90mA. So kindle seems to suspend.

2) Wake from suspend: As soon as the Kindle in suspend, I can not wake him up anymore. Cron does not trigger anything anymore. Does anyone knows if the Kindle DXG is able to use its RTC as a wake up trigger? There is not a /sys/class/rtc/rtc0/wakealarm file (like it is on a Kindle 3). But there is the Lipc property com.lab126.powerd rtcWakeup, which is supposed to be writeable. But I can not set the value, does anyone has some knowlegde about the Kindle 2 rtc?

Code:

# lipc-set-prop -i com.lab126.powerd rtcWakeup 300
com.lab126.powerd failed to set value for property rtcWakeup (0x100)

Code:

lipc-send-event com.lab126.powerd rtcWakeup -i 300
Failed to open LIPC
com.lab126.powerd failed to send event rtcWakeup

(could it be, that the rtcWakeup property can be only set, when Kindle is in 'Ready for suspend' state, like the deferSuspend property? https://www.mobileread.com/forums/sho...t=defersuspend)

3) WAN: How to properly start and stop the WAN connection. There are several ways to do it, which one is the most suited one? What are the differences?

Code:

lipc-set-prop com.lab126.wan startWan 1
lipc-set-prop com.lab126.wan stopWan 1

or

Code:

wancontrol wanon
wancontrol wanoff

or

Code:

wancontrol devicewake
wancontrol pppstart
wancontrol pppstop
wancontrol devicesleep

I have some ideas as a solutions for point 1) and 2), but I need to deside which one to follow... (Point 3 is of minor importance in the moment.)

First: Use of an external PIC microcontroller, which manages the charging and wake up: Kindle checks the internal accu and waits until fully charged, Kindle will send a signal through the soundcard/serial port to PIC, Kindle go to sleep. PIC "reattaches" the USB, thus Kindle wake up and start charging. Kindle does the downloading and returns to send the signal to the PIC and suspends again.

Second: External battery will charge internal accu directly (or replace the accu completely). Thus Kindle will fall a sleep on it own, and I dont need to care about charging the lipo at really cold temperatures (I expect up to -20°C ...). On wakeup time, PIC "switches" the power button to wake up Kindle.

Third: Update to software 3.x in hope, that the RTC wakealarm is useable ... Does anyone knows?

Honestly, I really would like to achieve my project with Kindle own functions. I dont want to have an external switching microcontroller. But, yeah, the winter is coming fast and the Kindle display need to go out soon ...

Cheers,
ansman

knc1 · 12-10-2015, 06:42 AM

A very advanced project.
For what purpose is this project?

Personal or Commercial?

Hint: You will find little help offered here for a commercial project unless your hiring.

Hint: People here will also be reluctant to offer help if this is personal in the sense of being your Master's thesis or Doctoral dissertation (or even a CS course project).

ansman · 12-10-2015, 06:56 AM

It's a personal project, but will hopefully be usefull for others since it should display the latest avalanche forecast for my region (east Switzerland) at a parking space where a lot of people start backcountry skiing tours...
And independent of the purpose, I spend already too much time on the project, I really want to solve and finish it.
cheers, ansman

knc1 · 12-10-2015, 07:49 AM

Quote:

Originally Posted by ansman

It's a personal project, but will hopefully be usefull for others since it should display the latest avalanche forecast for my region (east Switzerland) at a parking space where a lot of people start backcountry skiing tours...
And independent of the purpose, I spend already too much time on the project, I really want to solve and finish it.
cheers, ansman

Thanks for your quick response.

Sounds like a very worthwhile project - a dynamic, public service, warning sign.

Hmm...
Have you taken a stock DXG outdoors in winter temperatures to see how that e-ink screen responsds in the very cold environment?

You may have to consider spending some power to keep the screen warm enough to function.

ansman · 12-10-2015, 08:12 AM

I tried last winter once, and, yeah, the screen is slooooo ... ooow, but works. My idea is to give the eips command several times instead of only call it once, to make sure that all pixels are properly refreshed.

I dont plan any heating in the moment, and moreover bet on strong sunshine to heat up the box for a refresh ,-)

The external batterie will sit below the snowpack - if the snowpack is more than 40cm the temperature will not drop below zero.

Do you have any suggestions regarding the suspend and rtcwake issues?

knc1 · 12-10-2015, 08:23 AM

Quote:

Originally Posted by ansman

- - - -
Do you have any suggestions regarding the suspend and rtcwake issues?

Not at the moment.

All of the work done with the 2.x series firmware is going to require a lot of digging here.
You might check the FGA thread for 'how to find' suggestions.

The updating the firmware to 3.x series might be required - but the first thing to do is confirm that the 2.x series hardware had a functioning hardware 'wake' function.

= = = =

I will be 'out of the office' today -
Somebody else will have to staff the help desk.

ansman · 12-10-2015, 01:10 PM

OK! Some news to issue 2) rtcWakeup:

The property

Code:

com.lab126.powerd rtcWakeup

can be set when the Kindle is in state

Code:

Ready to suspend

That means, 60 seconds after switching to screensaver, there comes the 5 second time window to set the wakeup property in seconds (how many seconds the suspend should last). I have to investigate, if it works also for a longer period like 24h with a reasonable accuracy... more to come...

ansman · 12-10-2015, 01:16 PM

Does anyone has an idea if one can induce the "Ready to Suspend" state manually?

ansman · 01-30-2016, 02:03 PM

After several week of debugging, I managed to finish the above mentioned project. Its still not out in the field, because I want to have faster access in case there is still a bug (I guess) in the code.

When I find some more time, I will write it up. To be continued ...
BTW: thanks for this forum as a great repository of knowlegde about kindle!

ansman · 02-10-2016, 03:46 AM

You can find detailed description of this public service warning display on my blog.

12-10-2015, 05:10 AM	#1
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	Power consumption, sleep and wakeup issues Edit: more details on my blog... Servus, I am working on a project where the Kindle DXG has to operate autonomously in the field. It will be powered by a battery pack, which lets say provide power for several weeks or a month or so. It will will idle most of the time and only wake up every 24h, turn on 3G and download a background image from a server and suspend again. I know that my project is similar to the online-screensaver, but since the Kindle need to run from external battery the power consumption is big issue. I run into several issues, and I dont know if they can be solved and/or what is the best solution to achieve my needs. Therefore I ask you to give some hints or suggestions. Below I will list these issues. The software I use is Kindle 2.5.8 on model B009 (dxg). 1) Power consumption: If I attach the DX to a 5V power source over the micro-USB, the kindle never falls into suspend and also consumes around 90mA. This is way to much as an idle current. (I did not tried to change the governor to 'powersave' yet, but expect not to change much.) I read that Code: echo mem > /sys/power/state is propably not the every thing the kindle does to suspend. What would be the proper command? Anyway, if I do that, the charging LED turns off and I loose USBnet connection. If I measure the current drawn when replug the USB: 1st second ~0.8mA, then 1-2 second long ~8mA and afterwards 90mA. So kindle seems to suspend. 2) Wake from suspend: As soon as the Kindle in suspend, I can not wake him up anymore. Cron does not trigger anything anymore. Does anyone knows if the Kindle DXG is able to use its RTC as a wake up trigger? There is not a /sys/class/rtc/rtc0/wakealarm file (like it is on a Kindle 3). But there is the Lipc property com.lab126.powerd rtcWakeup, which is supposed to be writeable. But I can not set the value, does anyone has some knowlegde about the Kindle 2 rtc? Code: # lipc-set-prop -i com.lab126.powerd rtcWakeup 300 com.lab126.powerd failed to set value for property rtcWakeup (0x100) Code: lipc-send-event com.lab126.powerd rtcWakeup -i 300 Failed to open LIPC com.lab126.powerd failed to send event rtcWakeup (could it be, that the rtcWakeup property can be only set, when Kindle is in 'Ready for suspend' state, like the deferSuspend property? https://www.mobileread.com/forums/sho...t=defersuspend) 3) WAN: How to properly start and stop the WAN connection. There are several ways to do it, which one is the most suited one? What are the differences? Code: lipc-set-prop com.lab126.wan startWan 1 lipc-set-prop com.lab126.wan stopWan 1 or Code: wancontrol wanon wancontrol wanoff or Code: wancontrol devicewake wancontrol pppstart wancontrol pppstop wancontrol devicesleep I have some ideas as a solutions for point 1) and 2), but I need to deside which one to follow... (Point 3 is of minor importance in the moment.) First: Use of an external PIC microcontroller, which manages the charging and wake up: Kindle checks the internal accu and waits until fully charged, Kindle will send a signal through the soundcard/serial port to PIC, Kindle go to sleep. PIC "reattaches" the USB, thus Kindle wake up and start charging. Kindle does the downloading and returns to send the signal to the PIC and suspends again. Second: External battery will charge internal accu directly (or replace the accu completely). Thus Kindle will fall a sleep on it own, and I dont need to care about charging the lipo at really cold temperatures (I expect up to -20°C ...). On wakeup time, PIC "switches" the power button to wake up Kindle. Third: Update to software 3.x in hope, that the RTC wakealarm is useable ... Does anyone knows? Honestly, I really would like to achieve my project with Kindle own functions. I dont want to have an external switching microcontroller. But, yeah, the winter is coming fast and the Kindle display need to go out soon ... Cheers, ansman Last edited by ansman; 02-10-2016 at 03:48 AM.

12-10-2015, 01:10 PM	#7
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	OK! Some news to issue 2) rtcWakeup: The property Code: com.lab126.powerd rtcWakeup can be set when the Kindle is in state Code: Ready to suspend That means, 60 seconds after switching to screensaver, there comes the 5 second time window to set the wakeup property in seconds (how many seconds the suspend should last). I have to investigate, if it works also for a longer period like 24h with a reasonable accuracy... more to come...

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12-10-2015, 06:42 AM	#2
knc1 Going Viral Posts: 17,212 Karma: 18210809 Join Date: Feb 2012 Location: Central Texas Device: No K1, PW2, KV, KOA	A very advanced project. For what purpose is this project? Personal or Commercial? Hint: You will find little help offered here for a commercial project unless your hiring. Hint: People here will also be reluctant to offer help if this is personal in the sense of being your Master's thesis or Doctoral dissertation (or even a CS course project).

12-10-2015, 06:56 AM	#3
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	It's a personal project, but will hopefully be usefull for others since it should display the latest avalanche forecast for my region (east Switzerland) at a parking space where a lot of people start backcountry skiing tours... And independent of the purpose, I spend already too much time on the project, I really want to solve and finish it. cheers, ansman

12-10-2015, 08:12 AM	#5
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	I tried last winter once, and, yeah, the screen is slooooo ... ooow, but works. My idea is to give the eips command several times instead of only call it once, to make sure that all pixels are properly refreshed. I dont plan any heating in the moment, and moreover bet on strong sunshine to heat up the box for a refresh ,-) The external batterie will sit below the snowpack - if the snowpack is more than 40cm the temperature will not drop below zero. Do you have any suggestions regarding the suspend and rtcwake issues?

12-10-2015, 01:16 PM	#8
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	Does anyone has an idea if one can induce the "Ready to Suspend" state manually?

01-30-2016, 02:03 PM	#9
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	After several week of debugging, I managed to finish the above mentioned project. Its still not out in the field, because I want to have faster access in case there is still a bug (I guess) in the code. When I find some more time, I will write it up. To be continued ... BTW: thanks for this forum as a great repository of knowlegde about kindle!

02-10-2016, 03:46 AM	#10
ansman Junior Member Posts: 8 Karma: 10 Join Date: Dec 2015 Location: Davos Device: DXG	You can find detailed description of this public service warning display on my blog.

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