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91
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by Wannado on 01/Feb/2018 10:32:46 PM »
Yes, Gameboy Camera was tricky and handled different from normal carts.

From my notes on my Arduino GB reader:
WR, RD, CS must be low to get valid header
Hold CS low for read/write operations

That's a strange combination, pulling WR and RD both low. Do you know if (and why) a real GB would do that? Before v0.19 beta, the Retrode actually did it, but I'm sure that was unintentional.
Anyway, this interesting feature would explain why v0.19 beta and later cannot read the GB Camera. Quoting myself from the commit log:

Quote
Fixed issues with GB SRAM access: (...)
- Pulling /CS low when writing to mapper register address 0x1EFF caused SRAM to be corrupted. I read on the internet that /CS is required for SRAM access, but optional for ROM access. It seems that some MBCs take /CS to select SRAM even if the address is outside the SRAM range. I therefore guess that the real GB pulls /CS low only when accessing SRAM, not when reading ROM or writing mapper registers. And so does the Retrode now.
- Due to confusion about the port bits assigned to /CS and /RD, gbWriteByte allowed /RD to stay low while pulling /WR low as well. This caused SRAM writing to fail on MBC2.

Note that the SRAM corruption was hard to spot (only one byte changed, often an unused one). But my Kid Icarus savegame was affected noticeably.

Since reading the header neither requires writing to 0x1EFF nor to SRAM: Could the solution be to let auto-detection read the header as if it were a GB Camera, then chose the appropriate r/w methods based on the detected cartridge type (from the header)?
92
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by hadess on 01/Feb/2018 09:21:36 PM »
I'll give the Retrode and the adapter a good clean, and check if I can see any physical problems.

I retinned 2 connectors in the Game Boy adapter, and checked the solder points on the Retrode's Megadrive connector, but no difference I'm afraid.

At this point, it would be helpful to know if somebody else sees the same problem, with the same ROM name, on this cart, so that we know for sure that the problem is the Retrode's firmware, rather than going on a wild goose chase.
93
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by hadess on 01/Feb/2018 04:22:45 PM »
Received the second Game Boy Camera today, and can't access the SRAM just the same. Only one ROM file still named "WMuzoysMur.gb", as with the other Camera.

I'll give the Retrode and the adapter a good clean, and check if I can see any physical problems.
94
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by skaman on 29/Jan/2018 04:52:03 AM »
Yes, Gameboy Camera was tricky and handled different from normal carts.

From my notes on my Arduino GB reader:
WR, RD, CS must be low to get valid header
Hold CS low for read/write operations

There's probably more.  I wrote and tested the code a few years ago so my memory of it is pretty vague.  At the time, I wrote support for all of the mapper chips and also the Camera, Gameshark, Mega Memory, Nintendo Power carts, and all of the BUNG carts.

There were a couple of items that I never finished which were the MBC7 and TAMA5 saves.  One good thing with working on the Retrode code, I should be able to use the GG 93C46 EEPROM code as a framework to get the MBC7 93C56 EEPROM working on the standalone reader.
95
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by hadess on 29/Jan/2018 02:19:16 AM »
@hadess: Wren's broken plug-in also worked for quite a few things. The GB camera may just be more picky about some input voltage than your other cartridges.

Right, and I did inspect the pins visually, and couldn't see anything wrong. I'll test again with the new Camera when I get it. If the same problem happens, I'll break the multimeter out to see if there's any obvious connectivity problems.
96
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by Wannado on 28/Jan/2018 10:46:48 PM »
@hadess: Wren's broken plug-in also worked for quite a few things. The GB camera may just be more picky about some input voltage than your other cartridges.

@hadess, skaman: Since even the ROM header appears as garbage, the only firmware issue I could imagine here is something about the control signals like /CS etc. (timings, ...?). But why would only the GB camera notice it?
I remember that in v0.19 beta, I fixed GB SRAM bugs related to the control signals (see my commit message).
97
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by skaman on 28/Jan/2018 09:36:49 PM »
I haven't touched any of the Gameboy code so there won't be any improvements in the latest firmware.

I built a standalone Gameboy reader with support for all of the carts awhile back.  I'll look into porting the relevant code to the Retrode later.  I still need to finish up the SMS/GG firmware and release the VBOY SRAM firmware.
98
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by hadess on 28/Jan/2018 02:00:44 AM »
I'll try to update to the latest firmware to start with, and I'll be receiving another Gameboy Camera soon (not for this particular problem :) that I can test as well.

Same thing with ".24b-beta" from skaman. I'll see whether the other camera shows the same problem.
99
Support / Re: Cannot grab sram from Game Boy Camera
« Last post by hadess on 28/Jan/2018 01:30:29 AM »
I couldn't get the SRAM file at all from mine. Using the 0.20 Beta firmware that my Retrode 2 came with, I could only see a 1.2 megs "WMuzoysMur.gb" file on the Retrode. It works in 3 different Game Boy types, and I cleaned the contacts with alcohol first, then contact cleaner as a second pass, having removed the cartridge shell.
...
This is hexdump's output for those values:
00000140  59 7f 7f 7f 36 31 7b fc  75 76 7d 33 7f 9d ba f9  |Y...61{.uv}3....|
...
No .sav file, the ROM is "WMuzoysMur.gb".
...
00004000  f2 59 fb 59 76 5a 6d 5a  56 5a 4f 5a aa 5a d1 5a  |.Y.YvZmZVZOZ.Z.Z|
00004010  6a 53 53 53 4a 53 4d 53  52 53 57 53 74 53 8d 53  |jSSSJSMSRSWStS.S|
...


The data you posted doesn't look like a valid GB ROM to me (though I'm not a GB ROM expert). The only value that looks good to me is "fc" at offset 147, which identifies the GB Camera as such.

Right, it's total garbage, we agree.

Quote
Since you cleaned the cartridge's contacts, please also check the other connectors involved for dirt and damage: both connectors of the plug-in as well as the connector of the Retrode.

For example, Wren had a plug-in with broken ground pin on the GB connector. See gb-pins-small.jpg attached to the post http://forum.retrode.org/index.php/topic,338.msg2296.html#msg2296 (reply #8 in that thread). See also my reply (#10) in the same thread.

I looked at this, but I'm not sure why that would be the case. I managed to dump a number of other cartridges, including some with RAM, using the same adapter. If the problem was dirt, I'm not sure why when plugging it in again 2 months later I would get the exact same garbage (same filename, same data).

So, the adapter works (I just tried and successfully dumped a copy of Zelda DX), the camera works in real hardware. The only 2 things I can think of are software (though I'm guessing you expect it to work, if it did in the past), or a physical difference in the cartridge which would mean it doesn't connect as well.

I'll try to update to the latest firmware to start with, and I'll be receiving another Gameboy Camera soon (not for this particular problem :) that I can test as well.
100
That's an interesting finding.
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