Raspberry Pi Zero Serial Terminal for RC2014

[Peter Fischel]

I purchased this board and will likely have it in the next few days.

I was re-reading the sales blurb about it on Tindie and noticed that it says does not work with PI Zero Wireless.  I dug out my Pi Zero and found out it is indeed a wireless model.

Do any of you know if the terminal program for it has any modifications that made it work with the Wireless PI?  Its not a problem, I can order the correct one. Just to make sure I thought I would ask.

Peter J. Fischel

[Spencer Owen]

Hi Peter,

The original Pi Zero (up to and including version 1.3) uses a hardware UART, and that is what the PiGFX software uses.

The Pi Zero W, however, uses the hardware UART for the Wifi and Bluetooth.  So to use it with PiGFX, a software serial stack would have to written.  I suspect this would be quite a bit of work, and the only benefit would be that you can use a more expensive Pi without any additional features.

It is, however, possible to use the Pi Zero W with the RC2014 if you use Raspian (or one of the other full Linux distros), and then run Screen or some other terminal application.  This would be a much slower option, although, of course, you can then use the Pi to do all kinds of extra stuff if you want.

Cheers

Spencer

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[Shaun ONeil]

If you do go this route (run a full linux on the pi0w), it's worth noting that it's possible to revert the previous serial behaviour - https://www.raspberrypi.org/documentation/configuration/uart.md

In particular, look for "pi3-miniuart-bt", which gives you the hardware uart back, in return for atrocious bluetooth performance, and "pi3-disable-bt" which gives you the hardware uart back, and gives up on bluetooth completely.  I find these useful as the soft uart will drift its baudrate all over the place as linux scales the cpu clock - less than ideal when the uart is why we're here.  (Neither of these affect wifi, as its on an sdio interface, not uart)

As I understand it (eg, hand-waving and black magic) devicetree definitions use the linux kernel, not just the bootloader - so the same fixes won't work verbatim for PiGFX.

(If anyone does understand what these devicetree files actually do, please please please work it back into PiGFX.  If there's a magic poke to swap the hard & soft uarts, everything else should fall into place?)

On Monday, 29 January 2018 11:27:58 UTC, Spencer Owen wrote:

Hi Peter,

The original Pi Zero (up to and including version 1.3) uses a hardware UART, and that is what the PiGFX software uses.

The Pi Zero W, however, uses the hardware UART for the Wifi and Bluetooth.  So to use it with PiGFX, a software serial stack would have to written.  I suspect this would be quite a bit of work, and the only benefit would be that you can use a more expensive Pi without any additional features.

It is, however, possible to use the Pi Zero W with the RC2014 if you use Raspian (or one of the other full Linux distros), and then run Screen or some other terminal application.  This would be a much slower option, although, of course, you can then use the Pi to do all kinds of extra stuff if you want.

Cheers

Spencer

[Spencer Owen]

Thanks Shaun,

That's an interesting article.  The most interesting thing to me is that the hardware UART on the W ends up on GPIO 14 and 15, instead of 8 and 10 on the non-W.  That makes me wonder if, in fact, the hardware UART is already on 14 & 15, but normally Raspian diverts it to BT, and this patch simply undoes this?  If so, it should be relatively trivial to update PiGFX to use the different pins, and add a couple of jumpers to the Pi Terminal Module.  Hmmm... food for thought...

Spencer

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[Spencer Owen]

No, wait, scrub that.  I was mixing up GPIO 14 & 15 with pin header 8 and 10.  

Oh well, the hope was nice while it lasted :)

Spencer