Onchip RTC

[Evan Griffith]

Hi,

I am trying to get some clarity on the capabilities of the RTC on the BBBW.  Based on what I can see there is a nonbattery support powered RTC on the chip.  However in poking around online I hav ebeen unable to issue a command that allows me to put the BBBW into a lower power state and then wake up using the RTC.  For context what I am hoping to do is sleep for 10-20 minutes wakeup do something and then go back to sleep so that I can minimize power usage in a battery powered application.  Also I am running the latest Debian stock OS with kernel 4.9.59-ti-rt-r74.

thanks in advance for any help and let me know what info I should have provided to get better help. 

[Neil Hancock]

Hello Evan

 I've done it and designing a cape that manages the power by turning it off and on under external RTC control.

I've found this works

$ sudo su

$ echo 0 > /sys/class/rtc/rtc0/wakealarm

$ echo `date '+%s' -d '+ 1 minutes'` > /sys/class/rtc/rtc0/wakealarm

$echo standby > /sys/power/state

 shutsdown to 20mA then wakesup on deadline or any other event…

--
For more options, visit http://beagleboard.org/discuss
---
You received this message because you are subscribed to the Google Groups "BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/eb7d932f-775a-4d00-935a-a7df981d040d%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Evan Griffith]

Hi,

Thanks for the reply, I gave this a try and I can see that indeed it does go into a low power state, however it will not wake. 

These are the commands I entered for reference:

debian@beaglebone:~$ sudo su
[sudo] password for debian:
Sorry, try again.
[sudo] password for debian:
root@beaglebone:/home/debian# echo 0 > /sys/class/rtc/rtc0/wakealarm
root@beaglebone:/home/debian# echo `date '+%s' -d '+ 1 minutes'` > /sys/class/rtc/rtc0/wakealarm
root@beaglebone:/home/debian# echo standby > /sys/power/state

Is there a way to trace whats going on?  What would I look for?

Thanks for your help!

You received this message because you are subscribed to a topic in the Google Groups "BeagleBoard" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/beagleboard/RZfu2sd0wbU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to beagleboard+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAE_cRSfTP36rnA45xcx_5MKeED33xa1%2BmTAzAsJn-GK%3DDCw7Eg%40mail.gmail.com.

[Neil Hancock]

Sorry.... don't know how to trace it. Perhaps there is another command to enable the RTC interrupt, but I haven't kept track of how I go there.

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CA%2BUXKCop_bf2U_DfaOx8YmnWY%2Bdvoi11beLc5gZu1JWvhdiT-A%40mail.gmail.com.

[Lloyd Bailey]

Hi Evan,

I have a weather station project using a Beaglebone Black board to send data from a Davis Weather station console via an old Nokia phone. All Solar powered.

To save battery power the board runs every minute, sleeps every 5 minutes (during the day) and 15 minutes (at night).

The Kernel I use: Linux arm 4.9.67-ti-r82 #1 SMP PREEMPT Fri Dec 8 02:39:42 UTC 2017 armv7l GNU/Linux

The command to sleep: rtcwake -m standby -s 3600
This wakes up after 5 minutes or if I insert or remove the USB to serial TTL cable.

One of the biggest problems I have had is finding a pre-build Linux version that supports standby and USB numeration from standby.

Maybe this kernel will help.

All the best,

Lloyd.

[Evan Griffith]

Hi,

This seems to match what I am experiencing.  Did you compile the kernel yourself or use a distribution?  If you compiled it, did you find a good tutorial?  I found one for older kernels but nothing for new stuff.

Thanks for the reply, especially since this was an older post I had written off for dead.

--

For more options, visit http://beagleboard.org/discuss
---
You received this message because you are subscribed to a topic in the Google Groups "BeagleBoard" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/beagleboard/RZfu2sd0wbU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to beagleboard+unsubscribe@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/c81cd16b-bc65-4dc8-bc16-681b99b5d509%40googlegroups.com.

[Lloyd Bailey]

Hi,

I got the image bone-debian-9.2-console-armhf-2017-12-08-2gb.img.xz from here https://elinux.org/Beagleboard:BeagleBoneBlack_Debian
But the link to the image no longer exist. :(

The new images I tested do not support standby so I am sticking with this one.

All the best,

Lloyd.

To unsubscribe from this group and all its topics, send an email to beagleboard...@googlegroups.com.