Low cost Linux boards with deep sleep mode - Page 1
Forum section: electronics / beginners

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 01:22:05 am
content: I would like to build an inexpensive solar powered security camera. I want at least 1 megapixel resolution and five frames per second. So I'm looking for cheap Linux boards that can sleep and wake on GPIO from an IR sensor within a second.What are some inexpensive Linux boards that have deep sleep mode? Less than 5mA, and can quickly wake on GPIO.Alternatively, are there any MCUs that can connect a camera with 1 megapix and 5fps, then send that to a distant server for storage? ArduCAM is too slow.

author: Cliff Matthews
author_rank: Unknown
timestamp: June 01, 2017, 01:48:19 am
content: IMO security is serious biz. Solar novelty savings are easily outweighed often by just one theft (often occurring in hours when illumination IR LED's draw more power). To help get some answers, maybe check a major mfg. like Q-Seehttps://q-see.com/blogs/q-see

author: Muxr
author_rank: Super Contributor
timestamp: June 01, 2017, 01:50:52 am
content: Omega 2 apparently has a sleep mode (Raspberry Pi and its clones don't). I would do some research and evaluation of it.

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 03:11:47 am
content: The initial item to be videoed is a so not terribly serious yet, but that is a good warning as I had considered taking it elsewhere after the coop video was completed.And unfortunately the Omega team has not yet delivered on their promise of hibernation.Anything else?

author: Muxr
author_rank: Super Contributor
timestamp: June 01, 2017, 03:36:15 am
content: Odroid is the other option C1 has a sleep mode:https://forum.odroid.com/viewtopic.php?f=113&t=23641The other option you have is just streamlining Raspbian install on say RPi to support a bare minimum features so that it can boot quickly, I mean you only care about bringing up a camera quickly.. you can power up network and the rest of the system once you captured the event. Like recompiling the kernel to have bare minimum modules and modifying /etc/initd for minimum services could get your boot up to be as long a sleep wake up, with an added benefit of using no power when not active.You would however have to make a circuit that can switch on/off the Rpi based on some trigger, but that should be trivial.For instance these guys got it to boot in a second:https://www.raspberrypi.org/forums/viewtopic.php?f=72&t=48844edit: that's probably not the best example since they actually don't boot linux.. but here is an article talking about a boot up in less than 3 seconds..http://www.samplerbox.org/article/fastbootrpiI am pretty sure you could streamline it to boot and start recording even quicker than that.

author: floobydust
author_rank: Super Contributor
timestamp: June 01, 2017, 04:08:00 am
content: I find the system DRAM is the limiting factor and major waste of energy because it needs constant refresh. Getting to 5mA or less very difficult.Had a project like this (low power Linux) I'd started with NXP MCU and Micron mobile PSRAM (Pseudo SRAM) very low power 0.5mA standby (still doing refresh, 8M x 32) ).But you know Micron discontinued it as everyone's tablet/smartphone seems to not care, just use a bigger battery.I can't find details on RPi SDRAM what it uses in standby mode and what the MCU can need in sleep.That would be where I'd start.

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 04:10:51 am
content: Best I can tell the oDroid sleep is only an attached display. I'd pondered running a Pi but don't see how to get it under a second to boot. Maybe if I compromise on that one second delay. It's for a predator cam.I also wasn't feeling up to a power tweaking session; if there's an off the shelf board that does this fantastic.Microcontrollers can boot in microseconds; do you know of any (not ArduCAM) which can use a camera?

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 04:11:55 am
content: That's good info, thanks floobydust. Nice username BTW

author: CCitizenTO
author_rank: Contributor
timestamp: June 01, 2017, 04:46:59 am
content: I think getting below 5mA is going to be difficult or impossible unless you build your own.That said apparently Arduino's uses about 30mA at Idle and a RPi uses about 65mA at Idle (apparently can get lower by disabling the HDMI port and turning off the ACT LED. (https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=127210)That said the 5mA requirement may be overkill depending on your battery (for storage of extra solar energy) and solar panels you use. If you have like a 10W solar panel that would be plenty. Assuming 65mA and 5 watts that's a power requirement of about 0.32 watts?All you need is a sufficiently large solar panel (I would guess like 10-20 watt) and a battery (with maybe 20Wh) that can maintain a load of 0.32 watts under the worst possible conditions you experience on a regular basis where you live. Even if you get no sun for like 2 days it should be able to operate without interruption.

author: john_c
author_rank: Contributor
timestamp: June 01, 2017, 05:19:39 am
content: Try a 64-bit ARM board, such as PINE64. You might want to consider running Android, since it's more power optimized than most ARM linux distros. Apparently some people use it on PINE64. Although I don't know if there's any issue with it being headless.https://forum.pine64.org/showthread.php?tid=386&pid=2982#pid2982

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 01:22:50 pm
content: I had looked at Pine yesterday and for some reason concluded they don't have it. Even that thread seems anecdotal; I want better confirmation e.g. Something in their data sheet that says "Deep sleep mode uses 15mA and takes 300ms to wake. Use this command." I'll keep looking and may ask in their forum.The 5mA limit is not a hard limit, but beyond that the cost savings isn't really there. The goal is to build a cam product to sell, with the possibility of crossing over to actual security cameras for people, given the caveats above of course. If the device uses 100mA idle it requires a 12V 20AH lead battery to run three days, engineering in some extra run time for cold weather and 50% minimum SoC. $40 battery, $20 panel, $16 for a Pi Zero W (add shipping and SD card), $10 enclosure, $20 no IR camera, $5 IR LEDs, $5 charger and misc circuitry, plus my labor costs and still need to make a profit, and it becomes more expensive than most "wire free" battery powered cameras.Having 5mA sleep solves that problem.I guess deep sleep isn't quite ready on Arm boards, if the limitation is RAM refresh. I'm still interested though in MCUs with camera capability.I'll revisit ArduCAM. Perhaps it can be connected to a faster CPU like an ESP32 to give faster refresh and larger size. Alternatively I could sell it at a lower rate (how clearly do you really need to see a raccoon's face anyway) and hope for more resolution in the future, so that crossing over to human security becomes an option. I am not comfortable with this path though, because a grainy slow camera at (likely) $80 gets close to the price of much better resolution battery cameras. I want to offer a good value or not at all.

author: SlowBro
author_rank: Regular Contributor
timestamp: June 01, 2017, 04:14:11 pm
content: Thanks for the input from everyone. If there is no Linux board with sleep I don't believe I'll be able to compete with the likes of these, who probably are using some kind of custom ASIC.https://blinkforhome.com/pages/blink-xt-outdoor-camerashttps://reolink.com/product/argus/