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The Internet of Things is eating everything alive, and the world wants to know: how do you make a small, battery-powered, WiFi-enabled microcontroller device? This is a surprisingly difficult problem. WiFi is not optimized for low-power operations. It’s power-hungry, and there’s a lot of overhead. That said, there are microcontrollers out there with WiFi capability, but how do they hold up to running off of a battery for days, or weeks? That’s what [TvE] is exploring in a fantastic multi-part series of posts delving into low-power WiFi microcontrollers.
The idea for these experiments is set up in the first post in the series. Basically, the goal is to measure how long the ESP8266 and ESP32 will run on a battery, using various sleep modes. Both the ESP8266 and ESP32 have deep-sleep modes, a ‘sleep’ mode where the state is preserved, a ‘CPU only’ mode that turns the RF off, and various measures for sending and receiving a packet.
The takeaway from these experiments is that a battery-powered ESP8266 can’t be used for more than a week without a seriously beefy battery or a solar panel.
Power consumption and battery life remain limitations for IoT applications. How can they be overcome?
(Score: 2, Interesting) by Anonymous Coward on Monday December 17 2018, @09:04PM (10 children)
Bluetooth was designed to be low-power, short-range, and to play nice with a crapload of other bluetooth devices in close proximity. It's the perfect protocol for IOT devices.
Instead of screwing around with wifi to try to make it do what it wasn't designed to do, work on improving bluetooth.
(Score: 5, Informative) by EventH0rizon on Monday December 17 2018, @09:09PM (4 children)
I tend to agree.
And when we need more range than bluetooth, we use ultra low power LoRa Wan AVRs like this one:
https://wisen.com.au/store/products/whisper-node-lora/ [wisen.com.au]
(which really will run on a battery for months) to solve that same problem. Of course, we then have to contend with the miserly bandwidth available, but for some classes of problem it's sufficient.
(Score: 2) by suburbanitemediocrity on Monday December 17 2018, @09:19PM
I would think most classes.
(Score: 2) by c0lo on Monday December 17 2018, @09:30PM (1 child)
Really? $38 for a uC board?
Man, the shrimpy [shrimping.it] way [raspberryalphaomega.org.uk] with a good regulator [pololu.com] is cheaper - you should be able to find the components and put them together in a true DIY for less than half the price.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Interesting) by EventH0rizon on Monday December 17 2018, @09:52PM
The board I linked to is a LoRa device. It's a long range, low-powered wireless black box that has performed well (so far) for us in external environments.
But thanks for the Shrimpy link, that's a cool, bare-bones Ardiuno at a very nice price.
(Score: 1) by anubi on Tuesday December 18 2018, @10:38PM
Thanks for that. I am always on the lookout for stuff that may remain dormant for decades, but work when you need it.f
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Insightful) by c0lo on Monday December 17 2018, @09:10PM
Or... use wired WiFi. (grin)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by takyon on Monday December 17 2018, @09:13PM (2 children)
https://en.wikipedia.org/wiki/Bluetooth#Bluetooth_5 [wikipedia.org]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by urza9814 on Tuesday December 18 2018, @06:56PM (1 child)
My *standard* bluetooth devices usually have trouble reaching more than five or ten feet away...so with BLE I should expect to get two feet of range in my apartment on a good day? If I need less than five feet of range I'm just gonna run a damn cable. Faster, easier, cheaper, and *far* more reliable.
Recently I've been playing with some Adafruit Feather M0 wifi devices for building my next home automation setup though. They have just barely enough range to communicate with my router from almost everywhere in my one bedroom apartment (everywhere except the bedroom closet I think...which is actually pretty unfortunate), although some models do accept an external antenna if you need to improve that. Code is pretty simple too (they're Arduino compatible) and I think it even has SSL support...although personally I'm designing the system starting from the assumption that such devices are already compromised. I'll (mostly) trust a properly configured RasPi, but I don't know enough about those tiny boards yet...
(Score: 2) by takyon on Tuesday December 18 2018, @07:46PM
https://en.wikipedia.org/wiki/Bluetooth_Low_Energy [wikipedia.org]
If that is true, then Bluetooth 5 with the option to quadruple range absolutely improves range compared to your existing devices.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by VLM on Tuesday December 18 2018, @12:19AM
Of course it has to talk to something, and even if you play raspi type games the total wattage of "thingie plus what it uplinks to" is usually greater for BT than for "just another wifi device"
With a side dish of you can spec the BT scenario into incredible detail resulting in it beating a generic wifi solution... or vice versa.
TI has a "simplelink" series I have not played with but it only draws a couple LEDs worth of current when operating and practically nothing while sleeping and its marketed as TIs idea of an IOT system on a chip, I have no connection other than being vaguely impressed. I like my old ESP8266 with micropython on them but I find the TI CC3200 series strangely appealing. Of course its a more modern generation so best compared the seemingly eternal beta that is ESP32 series not the "ancient" ESP8266 series...
Something vaguely unclear is what IOT means which impacts its device selection. Is it my garage door or some spy monitoring thing in my pocket theoretically counting steps or a temperature sensor like my thermostat but somehow less useful or a videocamera doorbell or ...
IOT mostly seems in the marketplace to mean no firmware updates so you gonna get powned and they sell your personal data to some mysterious buyers.
(Score: 4, Informative) by isj on Monday December 17 2018, @10:13PM
"sleepy" Zigbee sensors can be very energy-efficient. One brand we work with (Nyce ( http://nycesensors.com/ [nycesensors.com] )) has a door sensor running on a CR2032 that lasts for about 4.5 years.
I saw Eurpy ( https://www.eupry.com/products/ [eupry.com] ) giving a talk a few years back about how they optimized the wifi usage in their temperature sensors. It seems they can run 2 years on two AA batteries.
(Score: 1, Informative) by Anonymous Coward on Monday December 17 2018, @10:22PM (2 children)
There's already a wireless protocol designed for this kind of low power - Zigbee. I'm sure I haven't replaced the batteries in my wireless thermostat for over a year, which uses this.
Though with being a different protocol to wifi or bluetooth (64-bit MAC addresses for example!), if a device really needs to be accessible to the Internet or to a more standard ethernet-type network, a gateway or bridging device would be needed to reach the nodes on the zigbee network.
(Score: 1, Informative) by Anonymous Coward on Tuesday December 18 2018, @07:12AM (1 child)
ZigBee has been common but is fading. You have the 6LoWPAN [link-labs.com] alternative as a better choice than ZigBee. ZigBee is encumbered by many patents, 6LoWPAN is an open standard [electronics-notes.com] and can be implemented freely. In fact, ZigBee is only royalty-free if used non-commercially [qi-hardware.com]. As an additional kick in the nuts, the ZigBee Alliance is intentionally incompatible with the most widely used free and open source licenses.
On the technical side, 6LoWPAN can also work over Bluetooth, since Bluetooth has come up several times in the comments.
(Score: 2) by isj on Tuesday December 18 2018, @05:17PM
Citation needed.
While I think zigbee is a minor abomination, I haven't seen much serious progress from 6LoWPAN or Thread, let alone interoperable devices.
(Score: 2, Interesting) by Anonymous Coward on Monday December 17 2018, @10:34PM (1 child)
Wake up every fifteen minutes to take a reading and send it over MQTT, then back to sleep. I've got a project that's been running like that for months on an 18650.
(Score: 4, Interesting) by VLM on Tuesday December 18 2018, @12:24AM
My experience with a ESP8266 is you actually need to set up a for loop to do that about 96 times and then software reset the device to handle memory leaks or WTF is wrong with it, but yeah, to a first approximation you're correct.
Also extra bonus hilarity for waking that sucker up then waiting for DHCP and all that junk. So its not like its awake one ms out of every 15 minutes its more like its awake a good ten seconds every 15 minutes. Still super huge power savings of course.
The MQTT server is a microscopic slice of a rack of vmware ESX cluster servers that draws about a kilowatt so your energy budget is kinda vague and hard to define. I'm probably averaging well under a watt for my rabbitmq instance which is a lot less than a pi, although the capital costs of the cluster are slightly higher than yet another raspi.
(Score: 2) by VLM on Tuesday December 18 2018, @12:05AM
I've used COTS zwave stuff and it works pretty well. You can even get a daughterboard/shield/wtf its called for a raspi to speak zwave protocol.
(Score: 5, Interesting) by coolgopher on Tuesday December 18 2018, @12:24AM
Haven't read the article(s), but if they're only getting a week out of it, they're doing it wrong. At $work we're using the ESP8266 for one of our products, and on a standard (good quality) 18650 battery we get a year, sampling every 30sec, uploading once an hour or so. If we upload less frequently, we can easily extend it a year and a half, at which point the self-discharge of the battery is becoming quite significant in its own right. This is on a combination of pure C and NodeMCU [github.com] for the higher-level logic (which only gets booted when we need WiFi).
If you're on battery, you have to approach the solution with that constraint as the first and foremost. The what-appears-to-be-typical attitude of glue-high-level-components-together-until-it-kinda-works doesn't fly in this space. Not if you want things to not run out of juice in a hurry.
(Score: 2) by corey on Tuesday December 18 2018, @01:47AM (1 child)
You said "deep dive"!
5 points for me.
(Score: 2) by fishybell on Tuesday December 18 2018, @02:31AM
And from the "plug-it-in" department. What is this world coming to‽
(Score: 3, Interesting) by fishybell on Tuesday December 18 2018, @02:30AM
Definitely worth the read. Very clear about methodologies and results.
More of this will always be welcome in my books (even if everyone is right, and low power and wifi were never meant to be mixed).