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'[EE] CRT Timings ?'
2008\01\03@074712 by Mauricio Giovagnini

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Hi, I'm trying to do something with some old monitors I have
around.

I have 2 HGC (Old Hercules PC board) monochrome monitors and
a couple of VGA ones and I would like to know how to deal
with them with a microcontroller.

I've seen around some open circuits to deal with them with
FPGAs and or Logic Gates.  I've also read about the MC6545
and similar circuits.

What I would like to know or to read about is the timings
and how they should be handled in order to make them work.
I've read here and there without any clear scheme or timing
graph.  Can anyone point me a link, book, pdf or something
related in this direction?

I know I need a fast device, I think a dspic 33F will be
enough for the Hercules Interface and for a VGA in 320x200 mode.

My goal is to replace the monocrhome Graphic LCDs a more
specific and 'bigger' screen.

Thanks in advance
Mauricio


--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

2008\01\03@080325 by Dario Greggio

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Mauricio Giovagnini wrote:

> I have 2 HGC (Old Hercules PC board) monochrome monitors and
> a couple of VGA ones and I would like to know how to deal
> with them with a microcontroller.
>[...]

> I know I need a fast device, I think a dspic 33F will be
> enough for the Hercules Interface and for a VGA in 320x200 mode.

Hi Mauricio,
I've done something with VGA monitors and 18F pics, reaching some 64x32
pixels b/n or something less with 4 shades of grey (mostly due to the
lack of RAM).

I'd like to do something new with PIC32, and/or using old VGA PCI cards
with a PIC (you've read about this on the forum, probably).

Still, a PIC32 or a dsPIC won't be able to do a True-Color VGA or
QVGA... in my opinion, or will have a tough work at it.

--
Ciao, Dario -- ADPM Synthesis sas -- http://www.adpm.tk

2008\01\03@081544 by Peter Onion

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On Thu, 2008-01-03 at 10:46 -0300, Mauricio Giovagnini wrote:
> What I would like to know or to read about is the timings
> and how they should be handled in order to make them work.
> I've read here and there without any clear scheme or timing
> graph.  Can anyone point me a link, book, pdf or something
> related in this direction?

Maybe this will help you.....
http://www.rickard.gunee.com/projects/video/pic/pong.php

PeterO

2008\01\03@084601 by Mauricio Giovagnini

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Dario Greggio escribió:
> Mauricio Giovagnini wrote:
>
>> I have 2 HGC (Old Hercules PC board) monochrome monitors and
>> a couple of VGA ones and I would like to know how to deal
>> with them with a microcontroller.
>> [...]
>
>> I know I need a fast device, I think a dspic 33F will be
>> enough for the Hercules Interface and for a VGA in 320x200 mode.
>
> Hi Mauricio,
> I've done something with VGA monitors and 18F pics, reaching some 64x32
> pixels b/n or something less with 4 shades of grey (mostly due to the
> lack of RAM).

Can you point me to where you read about the timings? That's
the main info I would like to know about.  I read many about
the implementation (everything done) but not about how the
signal is handled.

>
> I'd like to do something new with PIC32, and/or using old VGA PCI cards
> with a PIC (you've read about this on the forum, probably).
>

No, I haven't but I will :)


> Still, a PIC32 or a dsPIC won't be able to do a True-Color VGA or
> QVGA... in my opinion, or will have a tough work at it.

Sounds nice.  I've seen some devices with a ARM at 56MHz
inside. That's why I think a 33F could be enough for a VGA
at 320x200 but Im just guessing.  For true color may be a
FPGA is a more suitable device.



--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

2008\01\03@090546 by Dario Greggio

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Mauricio Giovagnini wrote:

> Can you point me to where you read about the timings? That's
> the main info I would like to know about.  I read many about
> the implementation (everything done) but not about how the
> signal is handled.

Here:
http://forum.microchip.com/tm.aspx?m=199298
and at http://piccoder.co.uk

Into the source (interrupt.c file) I cut'n'pasted the timings.


Horizonal Timing

Horizonal Dots         640     640     640
Vertical Scan Lines    350     400     480
Horiz. Sync Polarity   POS     NEG     NEG
A (us)                 31.77   31.77   31.77     Scanline time
B (us)                 3.77    3.77    3.77      Sync pulse lenght
C (us)                 1.89    1.89    1.89      Back porch
D (us)                 25.17   25.17   25.17     Active video time
E (us)                 0.94    0.94    0.94      Front porch

         ______________________          ________
________|        VIDEO         |________| VIDEO (next line)
    |-C-|----------D-----------|-E-|
__   ______________________________   ___________
  |_|                              |_|
  |B|
  |---------------A----------------|

Vertical Timing

Horizonal Dots         640     640     640
Vertical Scan Lines    350     400     480
Vert. Sync Polarity    NEG     POS     NEG
Vertical Frequency     70Hz    70Hz    60Hz
O (ms)                 14.27   14.27   16.68     Total frame time
P (ms)                 0.06    0.06    0.06      Sync length
Q (ms)                 1.88    1.08    1.02      Back porch
R (ms)                 11.13   12.72   15.25     Active video time
S (ms)                 1.2     0.41    0.35      Front porch

         ______________________          ________
________|        VIDEO         |________|  VIDEO (next frame)
    |-Q-|----------R-----------|-S-|
__   ______________________________   ___________
  |_|                              |_|
  |P|
  |---------------O----------------|

               

"VGA industry standard" 640x480 pixel mode

General characteristics

Clock frequency 25.175 MHz
Line  frequency 31469 Hz
Field frequency 59.94 Hz

One line

  8 pixels front porch
 96 pixels horizontal sync
 40 pixels back porch
  8 pixels left border
640 pixels video
  8 pixels right border
---
800 pixels total per line

One field

  2 lines front porch
  2 lines vertical sync
 25 lines back porch
  8 lines top border
480 lines video
  8 lines bottom border
---
525 lines total per field

Other details

Sync polarity: H negative, V negative
Scan type: non interlaced.

--
Ciao, Dario

2008\01\03@091627 by Mauricio Giovagnini

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Peter Onion escribió:
> On Thu, 2008-01-03 at 10:46 -0300, Mauricio Giovagnini wrote:
>> What I would like to know or to read about is the timings
>> and how they should be handled in order to make them work.
>> I've read here and there without any clear scheme or timing
>> graph.  Can anyone point me a link, book, pdf or something
>> related in this direction?
>
> Maybe this will help you.....
> www.rickard.gunee.com/projects/video/pic/pong.php
>
> PeterO
>

Thanks peter , I'll take a look although I've seen is for
handling a NTSC TV signal.  I'm mainly insterested on the
HGC (Hercules Graphic Controller) kind of signal.

What I'm looking for is something like what is explained in
page 16 to 19 of the MC6845 datasheet (link below).  This is
a CRT Controller with memory interface and much more.  I
want to replace its work with a microcontroller and RAM.

http://www.datasheetarchive.com/pdf/2272869.pdf

The datasheet is not very clear and I will like to know if
someone knows about a more didactic link about the subject.





--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

2008\01\03@112126 by Peter Onion

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On Thu, 2008-01-03 at 12:16 -0300, Mauricio Giovagnini wrote:
>  
>
> Thanks peter , I'll take a look although I've seen is for
> handling a NTSC TV signal.  I'm mainly insterested on the
> HGC (Hercules Graphic Controller) kind of signal.

Basic principles are the same though....  You need to generate sync
pules and video signals.

PeterO


2008\01\03@131555 by Mauricio Giovagnini

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Dario Greggio escribió:
{Quote hidden}

Thanks! I'll take a look.


--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

2008\01\03@131638 by Mauricio Giovagnini

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Peter Onion escribió:
> On Thu, 2008-01-03 at 12:16 -0300, Mauricio Giovagnini wrote:
>>  
>>
>> Thanks peter , I'll take a look although I've seen is for
>> handling a NTSC TV signal.  I'm mainly insterested on the
>> HGC (Hercules Graphic Controller) kind of signal.
>
> Basic principles are the same though....  You need to generate sync
> pules and video signals.
>
> PeterO
>
>

Its true.

The good news is that I talked to a friend that can borrow
me an old Hercules PC Board so I could be able to hang an
scope to it and debug it better than just try and error :)




--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

2008\01\03@135800 by M. Adam Davis

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The monitors are monochrome, and the following gives some info about them:

http://en.wikipedia.org/wiki/Hercules_Graphics_Card

720×350 resolution
Uses 5V TTL electrical signaling.
Horizontal frequency 18.425 +/-0.500 kHz, Vertical frequency 50 Hz.
Pinout: http://pinouts.ru/Video/MDA_pinout.shtml

You should be able to display video with that information, the only
thing remaining is to find front porch, back porch, and perhaps fiddle
with the sync pulse widths.

-Adam

On 1/3/08, Mauricio Giovagnini <spam_OUTmaugiovagniniTakeThisOuTspamyahoo.com.ar> wrote:
{Quote hidden}

>

2008\01\03@231529 by William \Chops\ Westfield

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On Jan 3, 2008, at 10:57 AM, M. Adam Davis wrote:

> Horizontal frequency 18.425 +/-0.500 kHz, Vertical frequency 50 Hz.

I'd strongly suspect that US monitors have VF of 60Hz.  There are a
bunch of advantages to having VF match local "line frequency", and
the wikipedia reference was to a german site...

BillW

2008\01\04@061711 by Mauricio Giovagnini

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William "Chops" Westfield escribió:
> On Jan 3, 2008, at 10:57 AM, M. Adam Davis wrote:
>
>> Horizontal frequency 18.425 +/-0.500 kHz, Vertical frequency 50 Hz.
>
> I'd strongly suspect that US monitors have VF of 60Hz.  There are a
> bunch of advantages to having VF match local "line frequency", and
> the wikipedia reference was to a german site...
>
> BillW
>

Yes, I was aware of that thread on wiki.  By the way, in
Argentina we have 50Hz too so I think I won't have problems
with that information.

This weekend I'll get the old HGC board and start to play
with it in my not so big free time. :) :)





--
------------------------------
Mauricio Giovagnini (Maunix)
http://www.maunix.com.ar
Cordoba, Arg.
LinkedIn Profile: http://www.linkedin.com/in/mgiovagnini

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