Questions MCU Video

I'm using Dalas/Maxim MCU - Microcontroller DS89C420NML - 40 pin dip on 33 MHz according to the schema printed in Elector (Elektuur) with photo PCB.





Do you use other scheme, better, simpler or do you have any suggestions for changes that should be made on this one?

1. How can I create sync for small resolutions and symmetrical images example: 16x16, 32x32, 64x64, 96x96, 100x100, 128x128, etc. I don't use CRT but shift register and flip-flop for clocking of data.

2. How can I create signal for asymmetrical resolutions as 320x100, 128x16, 64x48, 192x24, 80x8, etc. (LED matrix).

3. This is not a monitor but simply matrix where for the coordinates
X x Y + 1 OR 0 = for coordinates X x Y + (1=active=light 0=not active=blank) pixel.
This is a value for video signal for pixel that lights or blank - video sync and video create a signal. The question is what do I do with blank signal and how do I have to use it, I can't figure it out.

4. Where in the program is the option for changing the resolution and frequency and how to assign which PINs on MCU ports have to be active?

5. How to display some other image except the demo?

6. Is there in the program support for the COM port and how to (if it is possible) transfer characters directly from COM port to the video display (LED or LCD displays with progressive active scan [H/V - Sync + video]).
This MCU can be handled as a kind of shift register. For ready made LED modules can be used V + video as data in TTL and H-sync as SLC. I don't have this solution because even for an small display there would be an pile of chips needed placed on a small distance from LEDs and in the same casing, that I can not afford. Very complicated PCBs should be made, with probably a lot of wiring and that could be a problem , pretty big one - overheating. LED displays with ultra bright LEDs are known by heating, resonance and flickering (50-60 Hz) even if the RFS is higher than 100 Hz.
Is it possible to transfer files with text and image through the COM port to memory to be recognized by a microcontroller and translated to video signal?

7. I use 32 KB external RAM. How can I use RAM (32KB 62256 100ns) as a frame buffer or as a container for image (one or more)?

8. How to transfer from external RAM to video or directly to video memory? Where is that option in program, which part of the program?

9. Which program is used for writing of source code .asm and .icl files?

10. If I use an fixed resolution and change clock will the ratio between H - S in sync stay symmetrical or proportional to other signals?
Now I use clock 8,836 MHz for a small mono monitor 12" (PAL) and image is perfect. That means that I changed clock and image and video are still at the video output. In one text I found that you use 11,0592 MHz. Is that correct?




11. How can I or better said how should I reconfigure use of COM port for use of microcontroller with yours software. My present configuration is shown in the schema. Do you have any other or better schema for use of MCU?



This hardware project is very simple and interesting, but I have a slight problem: I can use just BASIC and C (visual studio, bascom, bas52, qbasic, visualc++, visual basic, etc) and that also limited.
That is why I have a lot of trouble with this project. Could you give me an example or changes on existing program related on question no.1. There is a chance that after investing many hours and work I could understand principles and finally understand how does that functions.

12. What are minimum and maximum values of clock and which crystals should be used. On my old (small) monitor only 8,832 MHz gives an good and stabile image. For me stability of the image on CRT is not that important because I don't use CRT. It serves the purpose of visualizing results.
I don't know why but everything above 10 - 12 MHz up to 33,832 MHz is without signal on port P1,n. Communication, changing of boud rate, CRC, verification and download works without any problems. When I place some other program into Flash memory, program works, ports are active. What cold be the problem? Maybe use of LS TTL or hc(hct) TTL-cmos? Looking at the schema of my MCU board I don't see the relevancy? RS-232 and reset condition can work with LS-TTL. Where is the problem?
How can I read part of the external memory bit-by-bit and send it in serial form on just one pin of the port. Example: 6KB - 8KB from memory on one pin of the port P1,5 and repeating 30 to 60 times in one second. Could you provide an example of software.


Thank you for your assistance.

With regards,

Kristijan Eladami

k.eladami@tehnotronic.nl



Tehnotronic, Joure, The Netherlands, Tel.: +31 513 41 60 11, e-mail: info@tehnotronic.nl