[9fans] small VFD display

[9fans] small VFD display

[Steve Simon]

Hi,

I want to drive a small (180x32 pixel) VFD display from plan9.
It talks i2c and can be driven as a text or graphics device.
One irritation is it aligns bitmap bytes verticaly. i.e. the display's
memory map appears to be a tradational 32x180 pixel display.

I am going to talk to this from a raspberry pi.

I see several options:

	resurect a small graphics library I wrote in the last milenimum, this
	knows about the weird layout but only supports rather nasty fonts and
	very simple windowing.

	talk text only to the display - again rather nasty fonts.

	draw the images in a plan9 window under rio. A seperate process
	which reads /dev/wsys/n/window, transforms it and sends it to the VFD.
	I would also need a backing buffer in VFD layout so only the changed
	bytes are sent.

Is there another way?

Could I run the plan9 graphics subsystem in a stand alone app rather
than involving the kernel?
I think I can but are there any examples of this?
Though this sounds nice, is it worth the hassle of doing this?

Any opinions?

-Steve

Re: [9fans] small VFD display

[yy]

On 6 May 2015 at 11:52, Steve Simon <steve@quintile.net> wrote:
> Could I run the plan9 graphics subsystem in a stand alone app rather
> than involving the kernel?
> I think I can but are there any examples of this?

wsys: https://bitbucket.org/yiyus/devwsys-prev/

It runs in unix. If you have a way to control your screen from some
linux in the raspberry, it should not be too difficult to make it work
as a cons or win device.

> Though this sounds nice, is it worth the hassle of doing this?

Probably not, but it might be funny.


--
- yiyus || JGL .

Re: [9fans] small VFD display

[Steven Stallion]

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Thinking out loud:

Most VFD's that I've dealt with were largely text displays - normally you'd
see an 8051 or similar driving a mess of shift registers. Essentially, one
would jam an ascii byte over GPIO and toggle a latch to update the display.
I'm assuming it will be somewhat similar for this display, even though it
supports bitmaps.

With that in mind, I'd be tempted to write this completely in userspace,
likely as an fs that overlays /dev/draw. It might be more hassle than it's
worth, but it would be rather fun to run the fs and fire up games/catclock
as a PoC.

Cheers,

Steve

On Wed, May 6, 2015 at 4:52 AM, Steve Simon <steve@quintile.net> wrote:

> Hi,
>
> I want to drive a small (180x32 pixel) VFD display from plan9.
> It talks i2c and can be driven as a text or graphics device.
> One irritation is it aligns bitmap bytes verticaly. i.e. the display's
> memory map appears to be a tradational 32x180 pixel display.
>
> I am going to talk to this from a raspberry pi.
>
> I see several options:
>
>         resurect a small graphics library I wrote in the last milenimum,
> this
>         knows about the weird layout but only supports rather nasty fonts
> and
>         very simple windowing.
>
>         talk text only to the display - again rather nasty fonts.
>
>         draw the images in a plan9 window under rio. A seperate process
>         which reads /dev/wsys/n/window, transforms it and sends it to the
> VFD.
>         I would also need a backing buffer in VFD layout so only the
> changed
>         bytes are sent.
>
> Is there another way?
>
> Could I run the plan9 graphics subsystem in a stand alone app rather
> than involving the kernel?
> I think I can but are there any examples of this?
> Though this sounds nice, is it worth the hassle of doing this?
>
> Any opinions?
>
> -Steve
>
>

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Re: [9fans] small VFD display

[Steve Simon]

> wsys: https://bitbucket.org/yiyus/devwsys-prev/

Mmm, not sure this is what I want.

I want the Pi to run plan9, and run a seccond display
(the vfd) on plan9 completely in user space.

It is an interesting project.

Personally I still harbour a wish to get a cpu server
running on windows - probably using named pipes instead of /srv.

Then I should be able to run "cpu -h dosbox -c catclock".
Again, its not very useful but would be fun.

More useful might be replacing some bits of windows dlls or
linux shared libs such that chrome is misdirected into rendering
on a remote plan9 box (without the overhead of X11, vnc, or remote desktop).

Thats is a lot more work and I will probably never manage it.

I an toying with the idea of using a raspberry pi2 running
Windows 10 as a cheap, low power "browser co-processor".

-Steve

Re: [9fans] small VFD display

[Ethan Grammatikidis]

On Wed, 6 May 2015 10:52:30 +0100
"Steve Simon" <steve@quintile.net> wrote:

> Could I run the plan9 graphics subsystem in a stand alone app rather
> than involving the kernel?
> I think I can but are there any examples of this?

vncs(1)



--
Developing the austere intellectual discipline of keeping things
sufficiently simple is in this environment a formidable challenge,
both technically and educationally.
 -- Dijstraka, EWD898, 1984

Re: [9fans] small VFD display

[lucio]

>  -- Dijstraka, EWD898, 1984

Huh?!

Lucio

Re: [9fans] small VFD display

[Robert Raschke]

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Typo of the name Dijkstra  :-(

http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD898.html
 On Jun 9, 2015 11:12 AM, <lucio@proxima.alt.za> wrote:

> >  -- Dijstraka, EWD898, 1984
>
> Huh?!
>
> Lucio
>
>
>

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Re: [9fans] small VFD display

[Ethan Grammatikidis]

On Tue, 9 Jun 2015 12:10:34 +0200
lucio@proxima.alt.za wrote:

> >  -- Dijstraka, EWD898, 1984
>
> Huh?!
>
> Lucio
>
>

search the web for "EWD898". it's a good read; fascinating how little
has really changed.

--
Developing the austere intellectual discipline of keeping things
sufficiently simple is in this environment a formidable challenge,
both technically and educationally.
 -- Dijstraka, EWD898, 1984

Re: [9fans] small VFD display

[lucio]

> search the web for "EWD898". it's a good read; fascinating how little
> has really changed.

A mathematician, a philosopher and a poet.  What's not to love about
E.W.  Dijkstra?

Oh, if the obscenely rich heads of computing empires could be but
worthy of washing his feet!

Lucio.

Re: [9fans] small VFD display

[lucio]

> search the web for "EWD898". it's a good read; fascinating how little
> has really changed.

Thank you!  At least we know what diabolical means, now!

Lucio.

Re: [9fans] small VFD display

[Giacomo Tesio]

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2015-06-09 20:34 GMT+02:00 Ethan Grammatikidis <eekee57@fastmail.fm>:

> search the web for "EWD898". it's a good read; fascinating how little
> has really changed.
>

I know it's off-topic, but it's funny to compare that Dijkstra's paper with
this video https://www.youtube.com/watch?v=qlRTbl_IB-s (and this site
http://2045.com/ !)

I've just found it, and suddenly I realized that all the crazy ideas I've
got in the past were quite realistic, after all. :-D


Giacomo

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