wiki:Notes/RaspberryPi/ZeroW

Raspberry Pi Zero W

https://www.raspberrypi.org/products/pi-zero-w/

The Raspberry Pi Zero W extends the Pi Zero family. Launched at the end of February 2017, the Pi Zero W has all the functionality of the original Pi Zero but with added connectivity, consisting of:

802.11 b/g/n wireless LAN
Bluetooth 4.1
Bluetooth Low Energy (BLE)

Like the Pi Zero, it also has:

1GHz, single-core CPU
512MB RAM
Mini HDMI and USB On-The-Go ports
Micro USB power
HAT-compatible 40-pin header
Composite video and reset headers
CSI camera connector

First Impressions

My first impression from reading the specs on the Zero W was "Wow $10. How amazing !".

After fiddling for a week with a Zero W as a minimal desktop, it's still amazing, but the performance is not stunning. In fact, one needs to go back twenty years or so to find an equivalent desktop system, maybe a Pentium 3 with 512Meg and a 32 GB disk ? Some GUI applications ( like Firefox ) are almost unusable on the Pi Zero. And get used to closing extraneous applications to prevent memory swapping, just like the 'old days'. So it's small and cheap but it's by no means quick ( or even quick enough ) as a desktop system.

Still, the performance per dollar ratio is a huge leap forward from 20 years ago, something like 40 times better, assuming the Pentium 3 system was about $400 in 1997. An amazing drop in price.

What's really amazing about the Pi Zero ( amazingly amazing ? ) is the low power consumption. A Pentium 3 system required the better part of 100 watts - the Pi Zero requires about one watt !!! That's close to 100 times better in terms of performance per watt power consumption. Note that when I say 1 watt, that's under peak loads ( running Firefox with CPU at 100% for a minute at a time ). Under a 'normal' load, the power consumption is nearer to 1/2 watt, say 120-150 milliamps. Sleep mode weighs in at 80-90 milliamps. Amazing amazing !

Remember that in absolute terms, the Zero W has barely enough performance for a minimal GUI desktop - shell out $30 more and get an RP3 for a desktop, it's an easy choice. However, for small battery-powered applications, the RP0 is revolutionary. We are talking about something like 30-60 hours running on cheap USB re-charger batteries. There's nothing that comes close to the Pi Zero W for delivering a minimal low-power Linux system, whether it's desktop or not.

Remote/mobile server applications of the Zero W may hold the most promise. For example configured as a Wifi Access Point running small HTTP servers, messaging and other PyWacket integration services, essentially what ever will run on Raspbian Linux in 512MB.

Many Java servers require over 512MB and maybe some Erlang applications, so they are out. Simple HTTP servers such as Lighttpd run in something like 20MB, with a significant workload going. Most Python servers run well under 100MB - standalone Trac requires about 40MB. The Tornado chat demo requires under 20MB.

For planning purposes, probably keep the number of active wifi connections down to a dozen or so - wifi power consumption and/or latency might be expected to increase sharply with more connections and user activity. Needs to be tested.

Conclusion: assuming a fairly 'medium' workload, a mixed bag of a dozen or so Python severs would run well within the 512MB limit, and maybe even with a NodeJS-based Etherpad Lite server ( consuming about 80MB ) as well.

Food for thought.

More to come.


http://raspi.tv/2017/how-much-power-does-pi-zero-w-use

... Essentially, the Pi Zero W seems to require 20 mA more than the no-wifi Zero. This is almost certainly due to the new radio chip. ...

Test RPZW (ma) RPZ (ma) RP3 (ma)
Idling 120 100 230
Load LXDE 160 140 310
Watch HD Video 230 240 350

My Zero W numbers generally agree, but seem to a bit lower. In fact, my RPi3 numbers seem to be a bit higher, not sure why. I'm using an Adafruit USB Doctor to measure current and there may be calibration issues.

My power supply is providing exactly 5.0 volts rather than 5.2 volts and that also could be a factor.

Frankly, I'm not confident about the numbers above, At a minimum, I need to rerun the RP3 measurements and see if I can resolve that. Based on my test workload, I'm starting to wonder if my RP3 numbers aren't also too low and the discrepancy is even greater than it appears.

Projects

The home automation application Home Assistant apparently understand the importance of the Pi as a platform. Home Assistant requires Python 3 - Pi Zero has Python 3.5

https://home-assistant.io/docs/installation/raspberry-pi-all-in-one/

Installing a fully configured version can be is fairly arduous and take several hours to complete.

They even have a stream-lined install for the Pi Zero ( with some complications ).

https://home-assistant.io/blog/2017/05/01/home-assistant-on-raspberry-pi-zero-in-30-minutes/

... First, download the HASSbian 1.21 image from 'here'.

From 'here' -> https://github.com/home-assistant/pi-gen/releases/tag/v1.21

Since I the developer of HASSbian have been moving, started a new job and so on I've had few moments over for HASSbian development ... The 1.2 release has been in pre-release for a few months now and just not communicated out that well. Hopefully this release changes that and I'll do my best to release more often.

Hmmm ... apparently uses pi-gen

https://github.com/home-assistant/pi-gen

The Haspbian image is built with the same script that generates the official Raspbian image's from the Raspberry Pi Foundation.

Interesting ... keep an eye on.


See RaspberryPi/WiFiAccessPoint

Last modified 11 months ago Last modified on 11/06/2017 06:57:05 PM