20/21-pin differences

[mal]

It's not really going anywhere ATM.

The theory is sound enough, it's just that I don't have...

A 8.467MHz crystal to 'complete' a 21 pin mod

or

any info on where to find a clock source on a 20 pin CD board.

While it would be fiddly, adapting the mod should be easy enough; we already mapped out the pins.

 

[ExCyber]

A 8.467MHz crystal to 'complete' a 21 pin mod

It looks like aside from getting a programmed 8.467Mz oscillator, the way to do it would be to get a 36.8688MHz crystal and divide it (not sure how simple this is; ideally it could be done by just running it through two cascaded T-type latches). By the way, is it known that this frequency works on 20-pin systems?

edit: I'm getting myself confused here. What you would need is a 33.8688MHz oscillator; a crystal alone would need other components to drive it.

 

[mal]

I don't really have the skills to do anything about a custom clock generator or frequency dividing. 🙁

Originally posted by ExCyber@Aug 26, 2003 @ 11:17 PM

By the way, is it known that this frequency works on 20-pin systems?

I assume that it does.

My 20 pin Saturn's CD board has a 36.8688MHz crystal, just like the 21 pin* ones do.

*most of them anyway

 

[ExCyber]

I'm not particularly knowledgeable about the bits and pieces of clock generation, but I could draw up a simple circuit to try if you can source a 33.8688MHz oscillator (I assume 74-series logic isn't a problem...).

 

[A Murder of Crows]

*looks back and forth between Ex and Mal like a Tennis 2K2 match*

go, guys, go!!!

=)

 

[Protosstic]

I know this thread wasn't really major after August of 03, but guys, you can't give up. Much information has been gathered on this subject, and I believe it is just a matter of time before you guys would have figured it out. Let's get this going again!

 

[mal]

I've got 11 days off over Easter and if I can find the time we'll see.

I'll need to get a new 20 pin Saturn though. I'm pretty sure I sent the PSU off to ajnin last year. I wonder what ever happened to him...

 

[Protosstic]

If all goes well with this trade of mine, i will be getting rid of my 20 pin saturn, and getting a 21pin.

 

[mal]

As you may have guessed, I didn't get around to this...

However, I'll shortly be getting some modboards that I should be able to hack to work in 20 pin Saturns. 😀

 

[Protosstic]

hehe it's alright, just recieved my model 2 saturn

 

[A Murder of Crows]

Originally posted by Protosstic@Apr 16, 2004 @ 08:48 PM

hehe it's alright, just recieved my model 2 saturn

[post=101412]Quoted post[/post]​

Well, it now seems like there are bigger problems....

been out of the scene for a lil while and am only now attempting to get myself going again, and when i do i see that pretty much everyone is SOLD OUT of mod boards...of all types!!!

i've got about 10 saturns sitting here waiting for various mods, and i only have about 2 boards left

so, if this project ever gets going again, i think the next logical step would be to start producing the mods ourselves

*sighs*

/<

not so good to see the state of things

 

[Pinchy]

Ive been analyzing the signals on the CD cable and want to know what the format of the protocol is.

The lines that yall call SH1-xx seem to be whats coming from the 'SMPC' or HD404920FS as the datasheet from charles mac's website. It appears to send a 13 byte packet to all the peripherals[guessing] on the bus every 16ms or so. Im just not sure what goes where. And im not sure exactly how it receives data.

When the door is open you get: 01,82,80,80,0,4a,98,20,0,2a,98,05,0

drive stopped:48,82,80,80,0,0,0,0,20,0,40,0,25,0

other: 62,82,80,0,0,0,e0,20,0,80,e6,20,0

thats assuming MSB first.

Does any of this data look familiar?

How exactly is the CD drive controlled? Is it memory mapped registers you poke to request data?

Heres some info on the clock lines:

9 -> JP5 (?) ~8.3MHZ clock

12 -> YGR-019B pin 131 4.1MHZ clock

I tried to kill some of the " YGR-019B" lines to see what they do and the saturn will seem to be able to recognize the disc it just doesnt see any game data , it will just recognize it as an audio disc.

YGR-019B pin 130 this lines seems to be some data but im not sure exactly what.

 

[ExCyber]

mal and I haven't done any protocol analysis since we don't have the equipment for it. You might want to get in touch with Mr. Sporty, who had a logic analyzer and was looking at it IIRC.

The lines that yall call SH1-xx seem to be whats coming from the 'SMPC' or HD404920FS as the datasheet from charles mac's website.

Those lines are connected to the CD block's SH-1 MCU (I don't have the P/N on me but it's probably HD64070xx/SH70xx). Some of them may be a shared data or address bus with the SMPC, but I don't think the SMPC and the CD block chat much; the SMPC pretty much just manages the controller ports, subsystem resets, and clock changes, and the CD block interface registers are in a completely different memory region than the SMPC interface registers.

How exactly is the CD drive controlled? Is it memory mapped registers you poke to request data?

The CD-ROM subsystem has a dedicated microcontroller+ASIC that do the actual talking (the SH-1 + YGR-019). Virtually nothing is known about the SH-1's firmware. The SH-2 talks to the CD block through a group of registers that is not as well-documented as some would like. Howqever CyberWarriorX knows quite a bit about it though, and he put together a CDC library that you might like to browse through. Chances are, though, that the protocol you're looking at is a CD Block <-> drive protocol and not a host <-> CD Block protocol.