Sporniket's log on hardware stuff

[sporniket]

Messing with python and Kicad. Goal : generate a symbol for a custom IC, from a datasheet written in markdown (to be nicely readable in github).

python-to-kicad-exp.png (75.68 KiB) Viewed 7863 times

[derkom]

In case you haven't seen these already, have a look at these existing projects who have probably already generated a lot of code you can use or learn from:

• https://github.com/boseji/Kicad-tools/t ... ter/libgen

• https://github.com/xesscorp/KiPart

• https://pypi.org/project/kipart/

[sporniket]

Thanks for the links @derkom, I will surely learn from them, especially kipart and its reverse convertor. I had only found uConfig.

[sporniket]

Little by little, I am gathering the parts for the H5 board... I had to put a sticker to some parts that are not immediately identifiables (I don't know all the store reference by heart, yet ). On a side note, as I'm new to this hobby (I mean, with my first STE, I never disassembled it, I just tried once to replace the 1MB RAM with a 4MB set bought on ebay without success), I was surprise how tiny those IC are (it looks bigger on the pictures from the store )

2020-11-10-01-loot.jpg (166.89 KiB) Viewed 7785 times

For my STE, I got this little one...

2020-11-10-02-diag.jpg (127.08 KiB) Viewed 7785 times

And ... I got a black screen on cold boot (vga mono output), yaart greets me with 4 bombs, and when I start gembench I immediately get a row of bombs before immediately returning to the desktop. Next month I'll have to get the diagnostic cable and a USB to SERIAL cable as well, and if I understood correctly the service manual, I place a little bet on the RAM for the root cause.

[exxos]

Just checking you know the cart does boot to a screen your can test ram etc ? If your getting bombs then then cartridge should boot up for you to do loads of tests...

[sporniket]

Yes, I expected to see a menu to show up, but there is only a black screen. Then I changed the jumpers to get either YAART (4 bombs on white screen) and again to get Gembench. I also read the posts about the cartridge ( https://www.exxosforum.co.uk/forum/viewt ... =27&t=1905 and https://www.exxosforum.co.uk/forum/viewt ... =91&t=3143 )

Right now I have opened the STE to unplug-replug the RAM and the other socketed chips, as I remembered reading this advices from other posts.

[exxos]

Might be worth cleaning the cartridge port connections as they pretty bad after 30+ years now.

[sporniket]

yes, and for this time, unplug-then-replug the RAM did solve the problem, I got the menu



EDIT : after some testing...

I finally have Tos 1.62, memory is good, some keys are unresponsive, and the "S" and "D" have bad contacts.

2020-11-10-03-diag.jpg (49.48 KiB) Viewed 7774 times

Yaart performed 10 cycles of tests without error, and GB6... wants more RAM

And... OH MY GOD MY COMPUTER SCREEN SUPPORTS COLOR MODE !!! (a little bit stretched, but it is supported, both 50 and 60 Hz)

2020-11-10-04-color.jpg (37.35 KiB) Viewed 7774 times

I didn't do the test last time because the official site says about the prolite xu2290hs-b1 that supported horizontal frequencies range from 24kHz up to 80, and horizontal frequencies range from 56Hz to 75... (https://iiyama.com/fr_fr/produits/proli ... cification)...

In medium resolution, some fine details show some imperfection (see the "B" and the"R" of "GB6.PRG")

2020-11-10-04-med-close-up.jpg (65.8 KiB) Viewed 7774 times

[sporniket]

First attempt at creating a schematic using kicad.

video-to-rgbs--2020-11-15.png (29.66 KiB) Viewed 7736 times

There is a project to mod a cheap and crappy GBS-82xx rgb to vga upscaler into a decent one : https://github.com/ramapcsx2/gbs-control

I felt like doing it, and so after searching, it turns out that having CSYNC is required, and I spent hours to find a correct circuit to get this signal from VSYNC and HSYNC (I mean, other than "short the two signals and Voilà !" or the XNOR gates based ones that ought to be incorrect if I follow this page : https://www.hdretrovision.com/blog/2019 ... ling-short).

Then I realized that I had the schematics of the STe and the H5, and the answer were there all this time... I have no idea of how it works beyond "Current from Vcc is more or less pushed back into the base of the transistor when Hsync and Vsync are high, triggering the transistor at the right time", could someone more knowledgeable explain please ?

[exxos]

All it does is to combine Vsync and Hsync on systems which do not have a modulator. It gives you "sync over composite". Normally machines with modulator output composite video which includes the syncs. Using composite sync helps to reduce "jail bars" in the video. A lot of platforms do this.