PPCenter :: devblog

I could populate 3 boards ... third one is not on the picture, while a couple of capacitors is missing on second one, but this is a matter of 5 minutes to solder.
After that, time was missing, and what's more problematic, ICs were missing too >_<

I soldered my last flash chips (on the right side of the cart), as well as my last USB chips and connectors (top left side of the cart) ... and my last 100nF decoupling capacitor (everywhere near all ICs) too ... it's a shame about the capacitors because they cost absolutely nothing and they are required everywhere in the cart.

So what's the plan from now ? I'm currently improving USB dev cart firmware, and plan to sell the completed cartridge on the bottom right corner of the picture when firmware will be ready for release.
From that money, I will buy a new stock of ICs to populate other PCBs
Why not buying ICs now ? Simply because I don't have enough budget for that, and also because buying ICs in few quantities is too much expensive : IC price decrease with quantity, and shipping fees are free when more than of USD100 of ICs are purchased.


So let's come the interesting part : firmware, which means software !
Last month I had enough about PCB design with Kicad, so that was good to get back with my Saturn and USB connect it to my laptop


So of course I lost a lot of time with stupid software troubles.
Here is a list of the troubles. I hope that writing them here will prevent me from repeating the same mistakes in the future.

 1) Data alignment problem : one structure is 1 byte packed, and some long word was put a non 4 multiple offset in this structure. It is usually easy to spot, but ...
 - It doesn't cause problem under yabause (? not verified, please tell me if I'm wrong), so this problem was unnoticed until I test it under real hardware.
 - It happened during program initialization, before USB transfer would allow me to easily find why my Saturn freezes.
 - I was sleepy at this time

 2) Adding byte size to unsigned long* pointer ... it resulted in pointer set 4 times farther than expected ... really stupid bug
Oh, and in the same fashion, a similar bug in Action Replay flasher utility prevented from writing more than half of flash memory size ... it's good that I could fix this bug before anybody notice it

 3) Saturn freezes when reading flash vendor/device IDs.
As usual, when Saturn freezes, it is during program startup, when USB can't be used for debug ^^;
This problem was the most interesting one : some parts of the firmware runs directly from Flash ROM, and it seems that reading flash vendor/device IDs makes whole flash returning theses IDs, resulting in invalid instruction from CPU ... this is just a guess, correct me if I'm wrong.
This problem was corrected in a very Q&D way : return 0xBFBF/0xB7B7 in FlashGetVendorID/FlashGetDeviceID functions
I have a better idea to fix this, but it requires to modify cartridge flasher utility ... I made enough flasher utility stuff recently (I'm enough in fixing compatibility issues with Action Replay old flash chips !), so I will fix this later.

You can download this utility here : flasher_20140824.7z → flasher_20140902.7z → flasher_arp_20150326.7z → http://ppcenter.webou.net/pskai/
Disclaimer : You will loose your cartridge backup data after reflash. And, I'm not responsible in the case I brick your cartridge and/or damage your Saturn.

Memory Card Plus looks like regular backup cartridge, but behaves differently : while regular backup cartridge provides memory on CS1 memory area, Memory Cart Plus have flash ROM chip mapped on CS0 memory area, as Action Replay does.
Consequently, Memory Card Plus boot before game on CDROM, and during this this time, it modifies some settings in order to make BIOS detecting this cartridge as a second backup memory device.

Everything is heavily mixed ... doctors say it might take time until I can start to eat more solid food.
I ate everything, except okayu (liquid rice) and tofu, not because I can't eat theses, but for taste reasons ...
Instead of okayu and tofu, I drank one ensure can

Tube is connected between my scar and this device, and negative pressure (like vacuum cleaner, but very very very very low) is applied to the scar so that it can close.
Around one week is required until I can get rid of this device.

Too bad I can't use the same technology to close scar in my mouth

Here is a list of problems I fixed to get the new compilers working :
 - Don't call directly ld, instead call gcc -o. Why ? because ld can't find properly path to libgcc.a ...
 - Consequently, some link parameters need to be changed :
    "--script bart.lnk" → "-T bart.lnk"
    "-Map main_elf.map" → "-Wl,-Map=main_elf.map"
 - Some signed/unsigned mess that need to be fixed ... old compiler was quiet about this, which made me not worrying about data signedness ^^;
 - Removed volatile keyword in function declaration ... it actually didn't made sense to use volatile elsewhere than in data declaration !
    /* Exit to multiplayer. */
    //(**(volatile void(**)(void))0x600026C)();
    (**(void(**)(void))0x600026C)();
 - Removed SBL sources that were used to read file from CDROM, because they don't compile properly except in -O0 (non) optimisation mode ... Instead, I use source from great CyberWarriorX library

The first one is "only" a cleaned-up, partially re-routed version of "Rev 1c ()" cartridge I used to sold on this homepage last year.
Can you spot major and minor differences between Rev 1c and new version ?

When I will be out of the hospital, I plan provide them for sale as USB dev cart .