zero wired connectivity

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mark
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zero wired connectivity

Postby mark » Wed Feb 06, 2019 6:30 pm

Do we have any way of using ethernet on an ultibo/zero? Do we have support for a usb/ethernet adapter?

If not, what wired options do we have? I have a project that could use an ultibo/zero connected to a windows host. Ethernet to the host would work well.

Another option is a retail usb/serial adapter connected to one of the zero’s serial lines.

Another option is to implement usb device mode. OTG (on the go) mode permits switching between host and device modes but that switching isn’t needed for this project.

Thanks, Mark
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Re: zero wired connectivity

Postby Ultibo » Wed Feb 06, 2019 11:33 pm

mark wrote:Do we have any way of using ethernet on an ultibo/zero? Do we have support for a usb/ethernet adapter?

Hi Mark,

We've noted previously that we have one of these devices which we think would make an ideal wired connectivity solution for the Pi Zero. We're still open to writing a driver for it if there is interest although it won't be a short term solution at present due to time limitations.

mark wrote:Another option is a retail usb/serial adapter connected to one of the zero’s serial lines.

For simple communications it is easy enough to invent a basic serial protocol that sends data between two hosts, it could even be based on Xmodem, Zmodem etc for which there are plenty of code examples around.

There are also USB to USB cables which connect host to host and often pretend to be a network device, again these would need a driver and I don't know if there are any standards between different products.
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mark
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Re: zero wired connectivity

Postby mark » Thu Feb 07, 2019 12:33 am

Ultibo wrote:
mark wrote:Do we have any way of using ethernet on an ultibo/zero? Do we have support for a usb/ethernet adapter?

Hi Mark,

We've noted previously that we have one of these devices which we think would make an ideal wired connectivity solution for the Pi Zero. We're still open to writing a driver for it if there is interest although it won't be a short term solution at present due to time limitations.

mark wrote:Another option is a retail usb/serial adapter connected to one of the zero’s serial lines.

For simple communications it is easy enough to invent a basic serial protocol that sends data between two hosts, it could even be based on Xmodem, Zmodem etc for which there are plenty of code examples around.

There are also USB to USB cables which connect host to host and often pretend to be a network device, again these would need a driver and I don't know if there are any standards between different products.


Thank you for your answers, Garry. For this project I can switch to one of the other pi’s that has ethernet. For this project, I don’t think pursuit of the usb/ethernet hub is warranted.

I neglected to mention that I do want to connect multiple pi’s together for a camera array (mentioned in the spi post) and for that I’m thinking of using the uart. Do we know whether Ultibo can sustain the 4Mbps max rate? (This assumes that line noise at that rate won’t be an issue after some error correction is applied at some level.)

Thanks, Mark
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Re: zero wired connectivity

Postby Gavinmc42 » Thu Feb 07, 2019 5:37 am

I have not looked at this recently but found info on remote GPIO
https://gpiozero.readthedocs.io/en/stab ... o_otg.html
Interesting, turn the Zero into a SD card reader?

I am reasonably sure when the Zero uses USB bootloader the VC4 does not change the USB OTG settings after it has finished.
The VC4 uses USB to load everything via USB, it cannot be a complex protocol because it must fit in the bootrom.
https://github.com/raspberrypi/usbboot

Uses libusb on the host and the Zero is a mass storage device?
USB serial port might be the easiest to get going for Ultibo Zero to Ultibo Pi3 comms?
My Cluster hats can turn on/off power, that acts as a reset.

Is there a USB reset command? And have I asked before?

The Zero could compress video so less data on the USB.
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Re: zero wired connectivity

Postby Ultibo » Thu Feb 07, 2019 9:19 am

mark wrote:For this project I can switch to one of the other pi’s that has ethernet. For this project, I don’t think pursuit of the usb/ethernet hub is warranted.

That's ok, we don't have a specific use for the Zero at present so we haven't bothered to pursue a USB to Ethernet driver, we figure most people really just want WiFi which is why there hasn't been much interest in a wired network option.

On the other hand the new 3A+ might have some potential uses ;)

mark wrote:Do we know whether Ultibo can sustain the 4Mbps max rate? (This assumes that line noise at that rate won’t be an issue after some error correction is applied at some level.)

In a general sense a data rate of 500KBps should present no challenge at all, however the unknown factor is that the UART hardware in the Pi doesn't provide any DMA support so all transfers have to be done in interrupt mode (or PIO mode). That can add extra overhead that makes it hard to know whether the 4Mbps is truly sustainable or not, the only real answer is to test it and see.
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pik33
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Re: zero wired connectivity

Postby pik33 » Sun Feb 17, 2019 10:42 am

Some time ago I bought this hat:

https://kamami.com/extension-modules-fo ... b-hat.html

The hat has 4 port USB hub connected to RPi Zero USB and UART to USB converter. The UART USB output also powers the RPi so only one cable is needed to run this.

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