Add support for EverDrive-64

[Polprzewodnikowy]

Direct reads from SD card to SDRAM is still unimplemented for everdrives in libdragon: DragonMinded/libdragon#345.

[riggles1]

As far as the old chinese clones go, is there a possibility of those getting supported? They're floating around everywhere at this point as people get them, then stop using them as they upgrade to something better.

With open source flashcarts being a thing it would be nice if new software for already existing clones can give them some better use.

Been recently returning to my old clone that was laying around after learning about alternative menues, to document the issues that affect altra64
https://github.com/ariahiro64/altra64/issues

As far as capabilities go, you have perfect compatibility with functional saving if you use two firmware SD cards, as the original clone firmware handles flashram saving but not alt/altra64. (except for Animal Crossing and Stadium 2 which are lost causes on older flashcarts anyway).

So the potential is there.

[Polprzewodnikowy]

Yes, i think it is possible to support ED64 clones as libdragon already incorporates libcart which claims to support these carts. SD card access shouldn't be a problem but one big issue before adding support for anything other than SC64 is figuring out how other flashcarts actually load data. Sadly there's little to none documentation of many registers used by ED64. There's altra64 code but as you already mentioned it has issues with some of the ROMs.

To summarize, ED64 support depends only on figuring out how to load data into the flashcart and correctly set specific registers. Anything other than that is generic to all flashcarts and should be already supported.

[riggles1]

Ah that makes sense, I'd suspect the big hurdle with that then would be flashram games as only ED64 clone firmware knows how to grab that save type. As far as loading the games everything console compatible loads and plays with altra64, given that the file+path character length isn't too long.

Would be neat to see some support at least I suspect a lot of these are basically dead weighs in people's collections. Appreciate the reply! Will be testing.

[networkfusion]

I have done some work towards this here: https://github.com/networkfusion/N64FlashcartMenu/tree/ed64-vseries . I am unsure of others progress in the area, but IMHO it should enable a Proof of concept.

And... definitely needs a more experienced C developer to improve the implementation!

[networkfusion]

I have now added a draft PR. If further help is needed with the implementation, please let me know.

[SlaughterRidge]

I can confirm that PR44 does at the very least run roms on the EverDrive 2.0. I tested roms that require the expansion pack and ones that do not require it.

EDIT: to add to this, saving does not appear to work, at least for the games I tested. The EverDrive 2.0/2.5 requires using the reset button to write save files to the SD.

[networkfusion]

EDIT: to add to this, saving does not appear to work, at least for the games I tested. The EverDrive 2.0/2.5 requires using the reset button to write save files to the SD.

Are you suggesting that the last played game is saving, but only when you have pressed reset? or it is still not working regardless of when you press reset?

[SlaughterRidge]

Sorry, to clarify, the EverDrive 2.0 and 2.5 require the user to press the reset button after the game itself saves. This is a requirement when using the official OS.

Using this build, the save files get create when launching the ROM (I can see them in the /saves directory) but pressing the reset button doesn't appear to write the save to the file. Upon re-launching the game, the save file isn't present within the game itself - in my case, I was using the Ocarina of Time as a test.

[networkfusion]

Thanks for the clarification. The PR does take into account the need to save on reset. But, was only tested on an ED64-P and also there has been a few upstream changes that could have broken it (since I merged). Rather than anymore noise on this issue, it would be better to note comments against the PR, and if you are able, help to get it to a state where it is able to be merged, it would be welcome.

[networkfusion]

Ocarina of Time

Also, since ROM's use multiple save types, it is possible that other ROM's are able to save correctly. Please test and show results for others that use EEP4K, EEP16K, SRAM , FRAM.

[networkfusion]

Adding notes:

Everdrive flashcart versions are quite convoluted.

ED64 Vseries 1-2
& ED64 Pseries (clones are the similar, but have different file path/names)
ED64 Vseries 2.5
ED64 Vseries 3 (USB+RTC)
ED64 Xseries 5
ED64 Xseries 7 (USB+RTC)

For carts that support USB, the implementation is solely based in software (i.e. relies on it's usage being implemented within any ROM that uses it), which differs from other more feature complete flashcarts.

Libdragon detects the bootloader using devwizard64's libcart library, it mainly works by detecting the bootloader version.

Certain fixes rely on the CPLD/FPGA being injected with updated firmware from the menu (filesystem) after boot.

The V3 can also handle all features and fixes specific to the X7 when loaded with the firmware from menu version 3.06 (very helpful for USB).

The N64FlashcartMenu currently differentiate carts by manufacurer, and potentially assumes model.

First step is to properly differentiate the model and set the required flashcart features.
Being able to inject the required firmware from OS3.06 for the V3 is very advantagous.