Possibility for 15.5kHz Hsync and 50 Hz Vsync (PAL TV)

[roberto314]

Hi, i have an EVA-1 which is an Video Adapter for the HX-20 Computer. It outputs 15.5kHz/50Hz with one color. I tried every firmware available (even the ones within other issues) but none of them work well enough. Additionally the horizontal resolution is 480px and vertical 200px. Furthermore the unit can change between 80 characters / Line and 40 char/line.
I had success with one custom firmware (i can't remember which) but the picture was too big.
I used a 1920x1080 Screen and the picture was bigger than full screen. VSync is positive, HSync i am not sure.
Is there any way to add this mode?
What Informations can i provide?
Thanks,
robert.

[scrapcomputing]

Hi Robert,
The current firmware was designed to be used with standard PC modes: MDA, CGA and both low and high-res EGA modes. It will auto-detect the correct mode by checking the VSync frequency and the VSync polarity.

Supporting other non-standard PC modes is possible but won't work well with the current firmware(s).
I am currently working on a redesigned firmware that allows you to configure your custom mode on an on-screen menu.
The firmware should be ready soon, I will share it with you once it's ready.

Thanks

[scrapcomputing]

Hi Robert,

The new version of the firmware is stable enough and supports manually setting the TTL options:

• Press both buttons until the new menu shows up. The text [AUTO-TTL] should show up.
• Press the PxClk button once to change it to [MANUAL-TTL] and more options will show up including Mode, resolution and X and Y offsets.
• Cycle through the options by long-pressing either button, change values by short-pressing.
• The settings are saved to flash after 5 seconds or so.
• If you need to reset to defaults unplug the MCE Blaster from power and power it on again while pressing both buttons until you see the led blinking fast.

Please try it out it may work better with your EVA-1.
Please note that I have not done extended testing on it so feel free to report any issues.

Thanks!

MCEBlaster.rev.0.2.beta.uf2.zip

[roberto314]

Ok, so i tried it and it is a little bit better BUT:
The menu is nearly useless with my monitor (BenQ 22" GW2265, FHD) because when something changes in the Signal from the MCE Blaster, the screen changes modes or whatever and goes dark for 3-4s and when it comes back on the menu from MCE Blaster is gone.
Suggestion 1: please at least double the time for saving the menu or, better, make a dedicated "Save Setting" Menu.
Second problem: With the Signal connected i can't change any settings because i can't see any picture probably bc. my monitor wants to switch resolution. Also I assume the software doubles the pixels, since i have 480 HORIZONTAL which is unusual to say the least, 640x200 EGA Resolution is too small.
What does the Values X:[MANUAL] 64 and Y mean?
Here are two pictures, one is from my EGA Monitor, the other is MCE Blaster, the best i could do.

[scrapcomputing]

Thank you so much for the detailed feedback!

1. Oh I hadn't realized that. My monitor shows some artifacts but that's it. Anyway I made some changes which should improve things a bit. I also increased the time-out to 12s. I might add a save button in the future, but I usually try to avoid those because the user may spend time messing with the settings and then forget to save, which can be frustrating.
2. So what is happening is that the on-screen menu is using some CPU resources that make the TTL reader a bit slower, which ends up messing up the input image. My monitor doesn't get bothered by it at all, but I guess I need to try it on a few others. I have made some changes to that code which should improve this quite a bit.
3. Regarding the resolution you are right, the 640 I am showing is the sampling rate. This is an internal implementation detail which I should probably hide from the user eventually. The problem is that the output buffer is 640 wide but the input 320 which would require pixel doubling horizontally which is not easy to do. So what we end up doing is just sampling 640 at double the rate.
   So to get the image to fit on your screen you need to decrease the pixel clock. This is not done in the "Manual TTL" menu, but under normal operation. Just click on the PxClk button once and then keep adjusting it with either button until the image fits.
4. X and Y are the horizontal and vertical offsets. They adjust the black borders from the last horizontal and vertical retrace. They should rarely need adjustment because because the auto-detection of the border usually works OK.

Please try the latest firmware: https://github.com/scrapcomputing/MCEBlaster/releases/

[roberto314]

I tried the new firmware.
How can i adjust the pixel clock? The explanation on this site doesn't seem to work, also there is no feedback.
If i press PixelClock twice the Image is gone and the screen stays dark. Also pressing Auto Adjust twice, which should bring the pixelclock back to its original value doesn't bring back the image.
Also pressing both buttons for two seconds doesn't bring the Info Menu.
If i reset the pico the info menu won't show with a videosignal present which defeats the purpose. In fact i've seen the Info Menu only once or twice - the other times the screen just stays dark and after some seconds the picture of my device comes back.
I am gone for the weekend, so there will be no testing.
-robert

[scrapcomputing]

Thanks for trying it out!

The pixel clock gets adjusted during "normal" operation (i.e., not in the Manual TTL menu).
With the input video signal connected and working, press the "PxClk" button once and the current pixel clock should show up on screen. It should display text like "PxCLK: 14.328MHz CGA 640x200".
Now you are in the mode where you can adjust the pixel clock. Pressing the PxClk button increases the pixel clock, pressing the AutoAdjust button decreases it. You should still see the text on screen showing the current pixel clock value. When you are done changing its value just wait for 12 seconds without pressing any buttons and the final value will be saved to flash. You will see a message about it on screen and the pixel clock text will no longer be shown on screen.

The "TTL INFO" screen shows up if you press the PxClk button for more than 1 second. This should only work when there is input TTL signal. This should always work, not sure why you get a black screen.

I hope this helps, let me know if you are still having issues with it.

[roberto314]

I think we have a winner! The Resolution settings are a bit weird (see pictures) but i've got it working.
It would be very helpful if you could add the Pixelclock to the new "Resolution Menu". At least the starting Point, i have 9.216MHz and starting from 14.xxx is really slow.

[roberto314]

I spoke too soon. It looks like the firmware switches off Vertical doubling >260 Lines. This would be more original to the original Format (see the first pictures from the EGA Monitor) but i cant get the picture to center properly. I think the syncpulse polarity is wrong.

[roberto314]

The picture is not bad. Unfortunately it doesn't sync on start. It uses 12.9kHz Horizontal Sync - which is totally off, 15.4 would be fine. I am not sure how i did manage to get the pictures from above. Everything works (except the offset).
2nd Suggestion: Change Sync Polarity via Menu or accept negative values for x- and y- offset.
3rd suggestion: Horizontal sync window, or fixed value.
-robert

[scrapcomputing]

Hi Robert,

Great to see you got a better image this time, and thanks for all your comments and suggestions!

It looks like the firmware switches off Vertical doubling >260 Lines. This would be more original to the original Format (see the first pictures from the EGA Monitor) but i cant get the picture to center properly.

Let me see if I understand correctly. You are saying that you would prefer to disable line-doubling for vertical lines < 260 ? I think I could add a menu option for it.

As for centering the picture there are two ways:

• By adjusting your VGA monitor. A lot of LCD monitors are pretty bad at centering non-standard images so you could try messing with the LCD monitor's manual image adjustments.
• By setting the X and Y offsets in the MANUAL TTL menu but these adjustments are rather limited.

In theory we should be able to adjust the borders in one more way: by adjusting the borders of the generated VGA signal but the Pico is not fast enough to handle the additional code needed for it. That might become available on the Pico 2.

I think the syncpulse polarity is wrong.

Are you referring to the HORIZONTAL SYNC in TTL INFO ? These are the values detected in the TTL input. This is probably related to your suggestions (see below), but I don't really understand what you mean.

Unfortunately it doesn't sync on start. It uses 12.9kHz Horizontal Sync - which is totally off, 15.4 would be fine.

So you get no signal when the computer starts. Does the computer generate a different TTL signal on start which doesn't match the one you set on MANUAL TTL ? If so could you check if one of the sync polarities changes between the two modes ? If they do we could use it to have two separate MANUAL TTL "profiles", one for each input mode.

2nd Suggestion: Change Sync Polarity via Menu or accept negative values for x- and y- offset.

I don't really follow how the sync polarities and the X/Y offsets are related. Then TTL input sync polarities are auto-detected and you don't need to mess with them. The output VGA sync polarities are fixed and don't need to be adjusted.

3rd suggestion: Horizontal sync window, or fixed value.

This is probably related to your 2nd suggestion, I don't really follow. Could you please elaborate a bit ?

[roberto314]

1st point: I find the 260 Lines limit no problem at all. I think it looks more authentic now, without the doubling. If one would like the doubling, just decrease the lines to <260.
2nd point: I made the observation that if the hsync polarity is wrong the picture is shifted somewhat because the Receiver (whatever TV that may be) uses the rising or falling edge only. So for ex. the polarity is pos. and the receiver uses falling edge, that means second egde, if the polarity is reversed the falling edge is the first one and so the picture is shifted.
I can't adjust my monitor more.
3rd point: I found out that if i increased the Pixelclock to 9.217MHz the autodetect of the sync pulse works.
4th point: Output sync pulses are out of the question, just input sync.
Addendum: I just found out that i had Composite Sync on Hsync. I removed the jumper and now the sync gets correctly detected as +/+.
Just the positioning of the windows would be a small ehancement. Is there a possibility to enter negative offsets?
Right now everything works fine. Even after power on.

[scrapcomputing]

I think I could do negative offsets. Let me work on it and I will get back to you.

[scrapcomputing]

The latest release (V 0.3 beta 1) adds the negative offset feature, feel free to try it out.

Thanks!

[roberto314]

I am in the middle of another Project. I will give feedback when i get the chance.
--robert

[roberto314]

Ok, i have news:
Horizontal Offset works until -32, after that o change. Unfortunately this is too little.
Vertical (negative) offset doesn't work at all.
-robert