deep sleep and voltage rail connections


My aim is to build low power(battery powered) 3G surveillance camera based on Beagle Bone(or black) and I have done some research regarding power management of BB and those attentions goes for BBB too:

Using prebuild image included in AM335xSDK 07_00_00_00( I can put BB in deep sleep giving command

echo -n "mem" > /sys/power/state

After that current draw goes from ~210mA → 150mA and BB wakes hapily up when I type any characters to console via USB-OTG

TI announces that power consumpion of AM335x is in deep sleep about 1mA so something is consuming current and I guess those are usb-circuits and lan-circuits at least. According BB RevA6 schematic lan and usb are powered via rail VDD_3V3B so I enhtusiastically command PMIC with

i2cset -f -y 0 0x24 0x0b 0x6b; i2cset -f -y 0 0x24 0x16 0x1f;

which turns rail VDD_3V3B off BUT unhapily also affects system reset, because U14B in schematic is powered via VDD_3V3B! In BBB if I have understand the schematic right, both VDD_3V3B and VDD_3V3A tied together via PMIC and regulators enable-pin so both rails are on or off.

after issuing command

i2cset -f -y 0 0x24 0x0b 0x6b; i2cset -f -y 0 0x24 0x16 0x00

current consumpition is zero, so there is no quiescent current, which PMIC has no control(you can guess that White Bone is really black after that command :smiley: )

So the after this scrambling I ask: is there something I have missed if I want to put BB or BBB deep sleep state with minimal power consumption and wake it up hapily with GPIO(this needs some config?) or it is overall possible with current schematics and if not is there coming new version of BBB where it is possible disable all unnecessary leak currents?

Thanks for your interest,
Mikko Pakarinen

When I issue the sleep command with "echo -n "mem" > /sys/power/state"
it effectively goes from 0.150A -> 0.025A.

I tested this with a BBB with only the debug serial cable attached to
it and a 3.14-ti kernel.

Which kernel version are you using?