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Naomi CF Boot with normal DIMM

yavuzg, Just curious if you have had any new updates or developments with your CF card and voltage experiments. Is it loading 100% of the time and what did you find out to be the "key" in making it work ALL the time.
Thanks.
 
arcadeWC, yes I'm still working on it. didn't wanted to pull false alarms though...

Haven't come to a 100% conclusion yet but I'm focused on signal noise due to overshoot, a side effect in digital circuitry caused mainly by un-matched impedance between two sectors of digital communication. The "english" explanion is; The communication line originating from a source (NetDIMM/DIMM board) and entering into a target system (CF Card) must be terminated electronically. Otherwise the signal (energy) bounces back causing "overshoot"...

Like this:

IMG_7863_zps0gz9pudy.jpg


See the ripples on the edge of the square waves? Those are "overshoot". Btw, this signal is from one of the data lines of the CF card monitored during a game load (prematurely ended). This is caused by couple of factors; Length of the communication line (i.e. the SCSI cable you are using, the PCB tracks), termination on the CF reader (pullup/pulldown resistors), the internal termination of the CF card used etc.

Switched to my NetDIMM during tests since the DIMM simply do not boot (black screen) when there is a problem. NetDIMM, on the otherhand, seems more tolerant to these problems it basically boot ALWAYS but simply cannot successfully finish loading a game . If the game is a small one, like Gigawing2, powerstone etc. it is 99% loaded successfully. If it is bigger, like MVC2, then its a good test subject ;)

Long story short, still continue to search for the "ultimate" solution (if there is one). It may be simple pull-up resistors on the control signals or data bus or total isolation with logic buffers.

There may not even be a solution. I mean Sega designed that official CF Reader to work with a NetDIMM and specifict type/brand of CF cards. I mean they may have known that inorder to support ALL the CF cards brands/model they may have designed a more complex CF reader with enhanced error correction. BUT that would be expensive and no reason for supporting all sorts of CF cards since you were supposed to get the CF cards from them pre-loaded anyway.

May be a real "industry grade" CF card works for you better? Have you tried any of those? I'm using the SanDisk cards I got from aliexpress cheap (they are probably knock-offs). In the mean time I ordered an official Naomi PSU with 5V and 3.3V voltage adjustments.
 
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Hopefully I see this screen 30-40 times in a row...

IMG_7886_zpsbqcgdbc9.jpg
 
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Thanks again for the information and research into this issue. I have tried a Bally CF card and a Sandisk CF card - not sure if I can tell the difference yet, but I have tried to use a higher quality card, if possible, and the Bally were used in a slot machine environment and should be somewhat "commercial" in nature. I do already have a Naomi SUN powers supply involved; should I still consider powering the CF from the Naomi motherboard rather than directly from the Sun PS? I am currently powering in the same fashion as the GD-rom disc player - six pin molex from the Sun PS. Again, I had the most success when "unplugging" the power to the CF adapter right before loading the game and plugging back in. Not sure what that did, but it definitely seemed to help. I still would like to power from the Board itself or the JVS I/O board (version 2) ideally - need to get a cable to allow this to happen.
In the end; it seems I should really find a Netdimm board as it is more resistant to these issues. I wish they were easier to find and reasonably priced. If anyone has an extra one available; I would appreciate purchasing one as well.
I hope your research continues to go well; I look forward to hearing your progress and eventually the successful load of the MvsC2 100% of the time. The CF option is great compared to the standard board/GD-rom swap - if it can be 100% consistent is the a tremendous setup and the best way to experience Naomi games in my opinion. I love my CF setup, in general, it is just the hope to not "hold my breath" which each load to see if it works.
 
I also gave up powering the CF reader from the filter board pins since its dangerous (cables may touch each other accidentally and make a short circuit on 3.3V line) and inconvenient. My CF adapter didn't have a voltage regulator so that was my only option back then (I do have another CF reader with onboard reguator now). Your CF adapter do have a 3.3V voltage regulator inbuilt so feeding it with 5V from anywhere from the system wouldn't make any difference...

Btw, I used 16 x 10K Pullup resistors on the data bus (i.e. D0-D15) and it seems it did help loading "troublesome" games. So far, with the pullups, MVC2 didn't failed to load yet (may be tested 20 times) BUT on the NetDIMM. I'm in a no-boot cycle (again) on the DIMMs.

One other thing to mention. In what condition are your batteries in the DIMM? I mean, if they went bad and even couldn't hold charge they still tend to draw current from the system to charge (even they cannot).You can replace them with new ones so that your load cycle reduces hence the probability of "no load" situations diminishes. OR, you can remove them completely so that nothing draws your precious current from the system. May be this helps...

You said, just before loading, unplugging and plugging the CF adapter from power seems helping. Just guessing here, it may be helping by issuing a RESET signal to the CF card, poking it to "start again". According to my observations, Naomi does not send an explicit RESET signal to the CF card during normal operation. Infact, the RESET line is soldered directly to Vcc (3.3V) on NetDIMM board where it is still connected to the Altera chip on the DIMM board...

I'm still working on this topic...
 
yavuzg said:
GOOD NEWS!!!

I solved it! I re-attached the netdimm daughter board so that I can now access to the Network Settings on the BIOS menu. Surprisingly (at least for me) I still see the IP settings there which gave me the impression that these settings are saved in the lower board. Anyway, I deleted the setting by selecting "Clear network settings". Then reboot. Now, even with the netdimm daughter board still attached, Naomi booted with "NAOMI GD-ROM SYSTEM" logo. Previously it was "Network System". Now I powered it off and reattached the GDROM only daughterboard and let it boot. Nothing seems to be different BUT when I powered off, attached my CF kit and reboot, WHOLA! It booted and loaded the game...

So I did this to my other DIMM boards and now all of them boots and loads games.

Moral of the story? I really do not know. I don't know if it was because of the hidden previous network settings or may be all of my DIMM board's SCSI connector had some wear or oxidation problem which went away with numerous times of unplugging & plugging.
Click to expand...
I mentioned it on tutorial, but unfortunately I'm not sure if I edited it on all forums.
Sorry for the mistake?!
 
yavuzg,
great work on narrowing down your Custom CF issue. I am in the same boat at the moment. I know I am resurrecting this old post but this is good information for me. I have one working CF adapter and one non-working. I can't for the life of me figure out why my custom build is not reading properly. I will need to check my voltages as well. Please do update us on if your loading success rate is 100%. Thanks!
 
Unfortunately I gave up for now but I planned two things to test for my future attempts;

a) make a custom CF reader from scratch with buffer chips on the data lines.
b) remove the SCSI socket on the DIMM board and fit the CF reader "inside" the DIMM board to eliminate the SCSI cable requirement and to make things more "compact".

The voltage level differences on the data bus and possible SCSI bus (SCSI cable) termination requirements makes my "DIMM" setup totally unreliable which is not what I want in a permanently cabinet setup.

However, the "NetDIMM" + CF setup is 100% reliable with my same cf reader and SCSI cable.

Anyway, I'll probably return to this subject in the future again but until that day, all my Naomi stuff is in a box :)
 
yavuzg said:
Unfortunately I gave up for now but I planned two things to test for my future attempts;

a) make a custom CF reader from scratch with buffer chips on the data lines.
b) remove the SCSI socket on the DIMM board and fit the CF reader "inside" the DIMM board to eliminate the SCSI cable requirement and to make things more "compact".

The voltage level differences on the data bus and possible SCSI bus (SCSI cable) termination requirements makes my "DIMM" setup totally unreliable which is not what I want in a permanently cabinet setup.

However, the "NetDIMM" + CF setup is 100% reliable with my same cf reader and SCSI cable.

Anyway, I'll probably return to this subject in the future again but until that day, all my Naomi stuff is in a box :)
Click to expand...
Ah ok. Keep us posted. This current project sounds interesting too.
 
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