R Pi 0

rickman schrieb am 14.12.2015 um 00:57:

The Pi2 model is more accessible when it comes to interfacing with hardware, network or peripherals. You can do so with the Pi0 - however, it's not as comfortable as with the model 2.

Best, Marco.

In embedded applications most of those tasks don't run. If you are short on horsepower, why run tasks that don't support the job at hand?

Embedded apps mostly don't need the missing interfaces. Embedded apps are using the I/O pins, not Ethernet. If you need those interfaces, then they are useful, obviously. I'm talking about apps where those interfaces aren't used.

A lot depends on how far you customise a standard installation to do your embedded task.

Run syslogd, or not?

For one not particularly typical example.

On your general purpose PC running a GUI desktop, network services etc. An embedded device will have been stripped down to the bare minimum (or built from scratch) because it doesn't need a lot of that stuff.

Or alternatively, an embedded device won't have been stripped down to the bare minimum because it was cheaper to add RAM than pay a competent coder to do that correctly.

It may be less overall effort just to use the OS "as-supplied" rather than spending time customising the OS and having less time to spend developing your own software for the task in hand.

I know which I would prefer to do!

Of course, if the small size or low cost of the R Pi 0 is required....

I think there is a tendency to use something like Busybox to do most embedded stuff.

Plus whatever custom app you want.

Mind you, looking at this machine there's well over 200 processes running, most of which seem pretty arcane..various daemons most of which probably wouldn't be required ion a single app platform.

Ok a lot of them are kthreadd spawns, which probably take no extra memory and so on.

It would be intersting to bring the machine up (or take it down) to non GUI mode and see what's left that isn't kthreadd stuff.

I am guessing it wont actually be that much, especially if systemd was ripped out ;-)

I am tempted to use the pi0, but I need IP connectivity there.

What hardware drivers for the already present hardware is there? IP over I2C? I know about the serial stuff, but a bus or ring with many devices on is a lot more attractive.

I don't need a lot of speed. telnet/ssh, snmp, and/or home-grown udp-based reporting, syslog messages etc. Even 4800 baud will do the trick, but I must have IP.

-- mrr

maybe an arduino would suit you better?

I have to say that what a Pi does well, it does very well, but its got a lot of stuff you don't need or want for a basic embedded app, and lacks a lot of stuff you actually do want, like ethernet hardware.

Its surprising how little of an OS you need to even drive a multitasking app on a simple processor.

PIC style chips are designed to do what you seem to be wanting - accept lots of input data, chew it a bit and spit it out via ethernet, usb or WHY.

I have looked at the arduino, but I prefer to have the general linux computer available. With the rpi-b I get that for around $50, power, case, cabling and sd card. This one has ethernet, and they really run reliably and well.

No, I want a rather full computer near the observation point, one that can run autonomously in prinicple forever (in case there are issues with management or connectivity) but can network reasonably well.

This networking is pretty basic though.

So the question remains, is there an IP driver for some of the builtin stuff on the rpi0; except running ppp over the serial interface.

-- mrr

I have such a machine I am logged into right now. A rpi-B (not b+), with 88 kernel threads (the [] ones in top). plus 14 system and

systemd-udevd, acpid, systemd, systemd-journald, xinetd, syslogd, klogd, init, haveged, systemd-logind, wpa-supplicant, dhcpcd, sshd and udevd, plus 2x sshd+bash and 4 daemons for my apps.

systemd brings up 4, the wifi/net 3, general devices 3. All of these are have very clear reasons for their usage.

-- mrr

You can apparently fairly easily connect an inexpensive Ethernet adapter based on the ENC28J60, over SPI:

These seem to be fairly inexpensively available on eBay, from China:

// Christian

There's the CHIP system (getchip.com), which is a $9 computer with a different focus than the pi0. There's very limited video without an add-on -- HDMI is an additional $15 for example -- but it has built-in wifi and bluetooth.

CHIP is designed around putting a full computer (with linux or whatever) in devices like digital cameras and wireless speaker systems, not around putting a full computer (with linux or whatever) on a TV. It grew out of a desire to sell a product for < $100, which with markup and parts besides the computer, the original Pi systems were too expensive for.

Elijah

------ has spoken with the CHIP people about the system

That's very handy info - thanx.

You just need to point pppd at the GPIO serial port, which is /dev/ttyAMA0

Theo

Thanks. Seems just what I need. Now to get pi0's in volume.

-- mrr

I already have tested that. Works, but need a dedicated serial on the other end, so does not scale very well.

The ether-on-spi means I can deploy cheap ethernet switches, and have a LAN.

The commenter said 85 MB in 3 min 45, which is just above 3 megabits/sec. More than enough for simple administration and telemetry.

I'll order some tomorrow.

-- mrr

You could also order a combined microUSB-to-ethernet & 3 port USB hub adapter for about $6 on e.g. dx.com and get plug & play 100 Mbit/s in a neater package.