DC SD Card Adaptor

It mentions in the Spanish 'release info' that FAT32 support has already been added, but do you happen to know if it works?

Sorry, I was having touble translating the page as Babelfish wouldnt work, but now I have managed to translate it with Google I understand. This picture by jj1odm shows how simply it can be done:-

Hope to make one similar myself but directly wired to the serial port internally :icon_bigg

Also read about removing the EMI capacitors off the motherboard, but i'm not quite sure how necessary it is to do this? Will the SD slot simply work/not work if I dont remove them, or does it just increase the speed/efficiency/reliability if I take them off?

I just thought that the USB SD card reader must regulate the voltage to the correct level anyway for the SD card, so we could use an almost direct connection (although im unsure why we would need to connect up the Dreamcast 3V line?)
Anyway, I suppose if it were that easy then somebody would have done it already!

 

Thread of the year and it's only April!

I'm so glad I have the day off tomorrow so I can fiddle with this stuff.

Since I don't have a DC in front of me,I ask: Is the serial port wide enough to justify mounting the reader inside the DC in place of the serial port? I've got a DC ready for some semi-sacrifice and definitely don't mind losing the port for something I would actually use a lot. I suppose you could dremel thin extensions on the slot if its too skinny and then still have the extra room above and below to get your fingers on the card for removal...

 

I dunno if the FAT32 support mean SDHC support but It'd be really cool!

I've tested jj1odm's elf/bin loader today and it works well

I had the caps problem, with them I got read errors all the time, without them I got none. However the spanish dudes had no problems about this. Maybe it's driver/lib side or maybe they simply are lucky (or I ain't) however it's really easy to remove and doesn't break anything.

I should get a test utility from the spanish guys soon so I'll let you know if SDHC works!

FG

 

we have nicknames just like everyone else FG, we're not just those "spanish guys" for god's sake LOL.
Sure contact me, I have the test app ready.
Fox69k with chui made a lib based on jjd01m's works which now uses KOS and is easier to use.

 

FG, on the page it says he tested SDHC cards to work.

This is cool news. I know very little about the DC architecture, but could a disc emulator be running to grab GDROM data from SD cards? This is the only reason I havent made a DC portable yet

 

Either way you'd still need to boot code from somewhere, so without other extensive mods (new bios) you wouldn't be able to have a disc-less DC.

Ponder on this: if it's possible to boot games from SD (commercial) then why hasn't it been done over coder's cable, where we actually have virtual 'smart' storage?

 

Beyond the complications of hooking GDROM functions, there's also the issue that the serial port is around 3x slower than the GDROM... Really a shame!

 

Actually, what is the maximum read speed of this SD card slot? I can only find mention on jj1odm's site of write speeds between 500kB/s-650kB/s, but theres no mention of read speeds, which are usually quite abit higher than write speeds.

As I understand it the Dreamcast GD-ROM Drive is a CAV drive with reading between 4x-12x (600kB/s-1800kB/s) So with the lower average access times for reading SD cards im thinking that the SD card slot might not be all that slow...

:shrug:

 

Lol I just didn't want to enumerate all the people involved in this
Send me the test app via email! I'll test it as soon as I'll get it!

@marshallh: Yeah but I can't answer this question myself as I didn,t tested it, and jj1odm's apps doesn't support it, for now...
PS: Do you happen to be Mathieulh ?

FG

 

Approximately the same, the SD card isn't the bottleneck, it's the serial port (and SPI protocol).

 

Well, theorically the serail port can go up to 1.5MB/s I think (the USB coder cable could reach this I beleive). Maybe, and don't quote me on that, some improvements could be done to reach this speed with teh sd-card, but i'd be the limit.

FG

 

I could be totally wrong here as the translation isnt very good, but jj1odm's site seems to suggest that the SH4 can probably handle upto 3MB/s using an external clock (on Pin 2?) to set the baud rate, but you need to remove the EMI capacitors and the software needs to support this feature.

(Note that im not sure if the the lowercase Mbps (Megabit) instead of MBps (Megabyte) is a result of mistranslation, or simply an error)

So is there any way we could add an external crystal to the SD Cart slot mod circuit to improve speeds?

 

That is 1.5 megabits/s, reaching the limit of RS232.

I think it's more like you can't go faster than 2 megabits/s with an external clock before the signal degrades, the UART however has no problems with 3 megabit operation if you bring the oscillator inside.

No, the baud rate is completely irrelevant to the SD card circuit, it uses the parallel I/O test register where toggling an output clocks the data. Speed is limited by 1) how fast the CPU can serialize/arrange the data and 2) how fast the CPU can access the register (any waitstates). Obviously unbuffered serial I/O at this speed is a very CPU intensive task so it should be pointed out it can't be done transparently (and can't remotely replace the buffered GDROM).

 

My bad, sorry!

Hey I just read the emuforge page on the sd-card, and it says SDHC is supported up to 4GB only, this is normal and JJ1ODM's apps support 4gb SDHC too.
http://www.emuforge.com/wiki/index.php?title=Adaptador_Dreamcast_SD

FG

 

They've also quoted a price when they don't even know how they're getting the end connectors yet, so...

 

I have my old DC Coder Cable, I think I can mod it to be a Coder cable AND a SD reader

 

any updates on this thing?

 

Does anyone have a picture of a DC where the SD slot is modded in the back, instead of the serial port?

 

That is just cool! Nice to see the DC alive and running!

 

This thing uses bit banging, not a standard implementation of the SD spec due to the fact it needs to be licensed.

Translation: it's going to be A LOT slower than the SD card in your phone/camera/USB reader.