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#1 23-03-2010 18:12:41

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Main Screen

This i haven't find a way to do it yet.
I found a lot of info mainly using Xilinx Spartan to simulate a VGA controller but i am still looking a simpler sollution maybe using a MC6845 (very difficult to find these days though) or any other controller.

I don't want to use the NB way of discrete TTL Logic using a ton of ICs.

Please post any idea that you may have.

 

#2 28-03-2010 13:48:03

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Re: Main Screen

Hi Chris...

Is it something like this you are looking for.. ?

http://www.4dsystems.com.au/prod.php?id=15

It aims for a serial connection to then uProcessor system. Should be possible.

Haven't read into details on "how and what" thou, but it looks neat...tongue

bg
Michael


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NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#3 28-03-2010 17:44:03

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Re: Main Screen

Hi Michael,

That is +1 for you i ll check it out when time comes for the VGA module but is certainly an easy to use controller.it has more features that i want but it will as long as i can transfer the video screen from Ram to the Vram in the controller fast  enough.

Many thanks ,

Chris

 

#4 28-03-2010 18:02:28

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Re: Main Screen

For a XILINX solution check the following link

http://www.trzy.org/

Last edited by cdesp (28-03-2010 18:03:00)

 

#5 30-03-2010 21:22:39

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Re: Main Screen

Yes, the Spartan clearly has the advantage of parallel interface. (It's the BartStation you think of, right?)

I think the uVGA is only intended to be used to manipulate it's one videoRAM. Not transferring a hole VideoRAM to it.

To move a 640x256 VideoRAM serial with 4MHz will take roughly 1/4 second not counting overhead in the uVGA.... naa ain't going to work. Maybe if it's a 8bit bus. (~3.5mS)
I guess 15 instructions at an average of 3cycles and ...what 20k of videoRAM. I'm not up to speed on how it's stored in the NB.

One way or the other, the VideoRAM has to be moved to an advanced VGA-controller.
It is going to take cpu-time.

How about a second Z80, doing only that task?.... Just a idea... hmm

bg
Michael


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NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#6 31-03-2010 18:08:37

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Re: Main Screen

Xilinx is a solution and i will have to follow that path if everything else fails.

Epson has a chip that can be programmed to interface with MicroControllers (16 bit mainly) but it is much sofisticated (144pin) for our project.
S1D13806 is the chip (http://www.gaw.ru/pdf/lcd/Chips/Epson/s1d13806tm.pdf)

If we could find something like that but with less features and more close to 8 bit Processors would be nice.

 

#7 31-03-2010 18:37:19

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Re: Main Screen

Most suitable so far is this project using a XC95108(PLCC) from xilinx (100 pins) that can deliver 640x480 monochrome vga signal which is more than enough for the newbrain.

Project page : http://elm-chan.org/works/crtc/report.html

Circuit Diagram : http://elm-chan.org/works/crtc/circuit_diagram.png
and modifications needed for vga monochrome : http://elm-chan.org/works/crtc/vga.png

Schematics to build a parallel download cable needed to programm the chip (Softeare is available for free at xilinx site. (they sell this for $125, $225 for the usb version).
http://www.xilinx.com/itp/xilinx4/data/ … ndixb.html

Last edited by cdesp (31-03-2010 19:09:32)

 

#8 01-04-2010 11:01:18

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Re: Main Screen

Yes, that's looks more straight forward.

Have you done some considerations regarding the videoRAM copy from the NB?
How long will it take?

From the old-days, I remember a Poke-value that disabled the screen-update and that speed up the NB with about 40%.
So does it have the power to do it, even with a parallel interface?


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#9 01-04-2010 12:51:24

cdesp
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Re: Main Screen

No I haven't but according to them it should be ok with RAM CHIPs up to 150ns.

The reading of course will be done by the xilinx putting the z80 on hold and taking control of the busses to refresh the screen.

So i think it would be faster than the real newbrain but that remains to be seen.

Anyway it is not the time to get into this i now have to make two pcbs one for the LCD 2x16 and one for the clock circuit (this gives all clocks from 4MHZ down to 1HZ by dividing by 2) to make room at my rasters for the rs232 interface that would make easier for me to change the EEPROM Contents by transfering data through the z80 directly to eeprom.

If someone has a better solution for the TFT/LCD Interface please let me know.

 

#10 01-04-2010 16:47:29

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Re: Main Screen

Ahh... The Xilinx does the copying job.... roll

For a new fancy LCD-design, check this link to Farnell.

http://dk.farnell.com/jsp/search/browse … 01+1004363

Farnell# 9448926 has a size as a normal NB display. 52€ thou, the smaller sizer is 25€.


I have a supplier at work, that stock these display. Maybe I can get some at a good price... tongue

bg
Michael


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NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#11 08-05-2012 17:56:47

cdesp
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Re: Main Screen

I found a new chip from epson which fits the project very well with less pins than the previous one 64 now from 144.

http://vdc.epson.com/index.php?option=c … mp;gid=210

 

#12 11-05-2012 19:08:44

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Re: Main Screen

Hi Chris...

Good to see you have progress.

This chip looks "easy" to use.
DIGI-Key has it to ~8$ and RS-Components to ~20$. That's not so bad...

Have you decided on a display. This might be the expensive part.

best regards
Michael


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#13 13-05-2012 13:57:34

cdesp
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Re: Main Screen

Yes it seems a good choice and a cheap one according to your research.
As for the panel its too early to start looking for one since i am busy finalizing the PS/2 Keyboard Interface.
But as you said it would be quite expensive hope for a price less than 100 Euros.
It should be capable of 640x480 at least but i think i will not find anything less than 800x600.

Screen will be the most difficult and complicated part of the project.

 

#14 13-05-2012 20:46:11

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Re: Main Screen

Hi Chris...

I think it will be vice to select a display that match the chips max resolution, 640x240.

I believe the NB's resolution is 640x256 ..?

As to getting raw display now-a-days, it is hard to find anything else but the 4:3 format in 640x480 or 800x600.

Feeding a native 640x480 display a native 640x256, will probably leave the bottom half empty.
To fill the screen, you will need a scaler to handle the signal -> difficult...
Scalers usually handles a composite/RGB/VGA signal and turns it into a LVDS-signal that fits the display as we know it from normal computer-monitors. To introduce a scaler is not the way to go...

If a 640x240 display exist (I believe it does, other vice why would someone make a chip in this format..) I do not know what will happen if a 640x256 format is feed to it... will it simply get truncated ?

Interesting.. I will start looking for a display... :-)

br
Michael


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#15 14-05-2012 00:02:45

Saphir17
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Re: Main Screen

Hi Chris...

Now you found the Epson chip.. ok, but take a look at this display manufacturer.

http://www.display-elektronik.de/lcd-gr … -table.htm

This interfaces directly with a 8bit databus.
To complicated to use..?

This Swedish electronic-supplier sell it to around 120€
https://www.elfa.se/elfa3~eu_en/elfa/in … ;toc=20375

I have a hard time to find 640x256 display, but this Panasonic keeps popping up.
http://www.aliexpress.com/product-fm/44 … alers.html

br
Michael


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#16 14-05-2012 20:41:57

cdesp
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Re: Main Screen

Hi Michael ,

yes the 8 bit interface will make my life easier but the swedish suplier has that screen at 140 euros + vat + tranfer fees it would cost as much as a new LCD TV wink.

i ll keep looking, something good will come up, or i ll make a CRT interface and buy a 9" crt lcd screen with 80€ smile

 

#17 17-05-2012 16:21:27

cdesp
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Re: Main Screen

Another sollution http://www.mitsutech.com/RA8835.html it's an older epson compatible chip.
this chip supports 640x256 mono which is the max resolution for NB.
But the problem with lcd is that the screen ratio is not 4:3 in that resolution so it should be like a widescreen sad .

One solution would be if we can double the vertical resolution so the res would become a  pseudo 640*512 but i doubt if we could find a chip to support this.

 

#18 19-05-2012 18:33:27

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Re: Main Screen

Hi Chris...

Yes, I have wondered about this wide-screen issue too.

A CRT do solve many of these format-issues.

There are some displays for car-use that run this resolution..(almost)
http://www.mobilevideozone.com/product_ … 997A86D4DA
...still pricey...

I have a video-converter-unit that converts composite to VGA, and I have to say that it is not the prettyst picture you get then a NB signal is feed to it into a TFT-monitor. Maybe it's also something with signal strength that is the problem too...? Have read on a ZX-81 forum that signal can be improved.
This is a scaled picture and that adds to fuzziness of the picture.

I think it is wise to stick to the Epson chip and find at display that fits.
Btw. look at this : A ready PCB with the epson chip http://www.mdejong.de/produkte.htm

How about a LCD display? :
I found this, but it looks small and have the resemblance of a game-boy display.
http://www.p-wholesale.com/cn-pro/2/163 … 59019.html

br
Michael


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#19 22-05-2012 20:10:06

cdesp
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Re: Main Screen

I did some searching for an lcd panel that has the 640x256 resolution and nothing came up at a resonable price.
So since that resolution is made for pal systems i think the system should work with PAL output at 640x256 and use a PAL lcd screen which come at a very resonable price and several sizes.

some examples:

http://www.ebay.co.uk/itm/7-TFT-LCD-Rea … 289wt_1139

http://www.ebay.co.uk/itm/7-TFT-LCD-Rea … 27c683af75

 

#20 22-05-2012 22:47:11

Saphir17
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Re: Main Screen

Yes, it's a quick and cheap solution.

I think it will be a fuzzy image or at least the same as hooking up a NB to a TV.. but it's a start.

Looking forward to see what you come up with.

br
Michael


Aarhus, Denmark
NewBrain's: Model A & AD, ExpansionBox, DiskController + Drives, ROM-Box
 

#21 02-06-2012 17:26:28

cdesp
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Re: Main Screen

I manage to get a monochrome signal using the xilinx 9572 CPLD. I am using the 16Mhz crystal so ia can put 1024 pixels on screen and 305 lines but i reduce this to 640x256 to be compatible. I ll order a 13,5 Mhz crystal as this is better for PAL signals. The D/A converter i am using is as simple as it gets several resistors forming a R/2R ladder for 3 bits of information data, hsync and vsync. I have to make something better to stabilize the signal but for now it is good.
I ll try to Interface this with the cpu and see what will happen.

Pictures at the gallery.

 

#22 15-07-2012 14:36:53

cdesp
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Re: Main Screen

I order two Sony cxa1645 to take care the analog part of the video generation, i am waiting for them to arrive.

 

#23 27-06-2014 18:32:25

cdesp
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Re: Main Screen

The laptop screen will be, as the original, a monochrome composite signal and you can connect any compatible tv screen lcd or crt.

I am using two CPLD chips from XILINX one XC9572 for generating synchronisation signals (VSync and HSync) and the other is the XC95108 that has all the logic to read data from the RAM chip, put the cpu on hold (BUSREQ) and of course displaying either text (80/40 chars) or graphics.

I manage to do that but the signal is not as stable as i would like, and i have some problems to solve until i can say it is ok.

Check the videos to see

40 chars
http://youtu.be/-wjAxnkiWLo

80 chars
http://youtu.be/nUy2k_mx3Qo

Graphics
http://youtu.be/_NGrQRU40HM

 


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