BennVenn
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Australia

Hi,

This thread is intended to document the Backup Block Linker from conception to maturity (This may become fairly technical). What Is the BBL?

A small, USB Thumb Drive size dongle that allows the backup and restoration of LSDJ 128K save files in a portable storage medium. Initial design specifications include:

-Powered by the GameBoy
-No less than 2Mbytes of storage (16 x 128K save files) with potential to increase to 8Mbytes and beyond.
-Fast Load + Save time- Less than 30 seconds
-Compatible with all 8-bit GameBoys (and the GBA in GB mode)
-PC link for download/upload
-Low final cost
-Flashed Based so no data retention problems
-Compatible with ALL flash carts (With the modified LSDJ - Supplied)
-Physically rugged construction

Initially I thought there could be issues with the GB supplying power via its data lines, but that is not necessary. 5V (more like 4.4v due to the diode its fed through) is available via the link port too. That was my only concern.

So all I need now is some input on the minimum flash size the Backup Block should have and I'll get a batch prepared. I've got the spare parts floating around here to build a prototype (1 and 2mbyte flash IC's)

A 128K write to my 2mbyte flash ic will take 0.9 seconds, ~4 seconds to get the data in there and a 128K data transfer via the port will take ~4.8 seconds (taking into consideration the GameBoys Link speed and CPU execution time for ~21 cycles) Totalling less than 15 seconds. Add some  protocol overhead and some AVR processing and we're looking at just under our 30 second target.

So that's where I'm at. Ready to build the prototype and if enough interest is shown I'll get a small batch of PCB's made up, assembled, programmed and shipped out.

Price?
$3USD per 2mbytes Flash (thinking space for 4 IC's on the PCB)
$3USD - Atmega328P
$5USD - GB Link Plug (GB or GBC)
$2USD - PCB
$1USD - Discrete Passives

That is a rough figure of what this thing will cost. There will be other expenses like shipping, enclosure etc...

If we can get an order of say 10-20, we should be able to shave a few more $'s off that price.

Now its over to you. Get your name down if you would like to help get this project off the ground. The first 10 will be assembled free after that they could either be sold as a kit, or sold assembled for a few extra $'s.

I have the firmware just about finished as a project I completed a few years ago used very similar hardware. If someone would like to handle the GB software side of things that would be welcomed (I'll be busy with another project for the next few weeks - Someone more fluent in GBASM can achieve what I could with far less time and effort). We can discuss protocols and timing as we go.

Look forward to hearing some feedback!

-Ben

egr
Offline
Abandoned on Fire

I'm down to help and purchase once they're ready. I'll make a wishlist of functions and add it here later.

Another thing: I notice that you're supplying a patched lsdj rom. Are you checking licenses or coordinating with Johan somehow?

Edit:

Software wishlist - able to rename sav files using the gb... that's about it tongue

Hardware wishlist - male link connector so no cable is needed, same for usb if pc connection is included (so like a link connector on one end and usb on the other)

Last edited by egr (Jan 17, 2015 8:01 pm)

BennVenn
Offline
Australia

I now supply all patches as an IPS Patch file. That isolates me from the whole 'registration' issue. I'd love to co-ordinate this project with Johan though unfortunately he doesn't have the time to respond to my emails. This really delays progress as I have to reverse engineer his code line by line to support my hardware requirements. It sure would be easier him adding 2 lines of code in his source and recompiling than me spending 8 hours digging through C "optimised" assembly. I'm sure he has his reasons.

Naming the save files is no problem, that is all in the GB code.

I'm thinking having the SPI Flash IC connected straight to the Link port with the AVR controlling its /CE line. Have the AVR snoop the data on the bus and when an enable string is detected, it allows data throughput to the flash IC. When transfer is complete, or an idle time has elapsed, disable the /CE line. This could allow the use of an ATTiny and just about halve the cost of the whole dongle. This would require some trickery with the AVR controlling the clock line and could just about halve the 128K transfer time. Something to look into

-Ben

scrmwzrd
Offline
SYD

This is exciting, will the usb part work like a
And will here be mac OS X compatibility? I'm still new to this, but I only have macs and would like to know about that.

BennVenn
Offline
Australia

Yes, Mac wont be an problem with this hardware. A simple program to get all 16 128K saves off into a folder will be easy. Likewise for getting them back on.

Xuriik
Offline
Puerto Rico

Very interested. You should talk to nitro and work out LittleFM compatibility, make it all just one big ips patch, or at least make sure the two patches don't conflict. It already supports sending save data through link cable so it shouldn't be too hard!

BennVenn
Offline
Australia

Sounds like a good idea.

I've got the hardware sorted, like egr suggested, a Link plug on one end, and usb male on the other.

One problem is adding the 5v pin to the link plug. Not an issue with GBC but DMG style plugs require sacrificing one plug to make upto 4 DMG plugs with the extra pin. (OR sacrifice the gnd pin and use the shield which is also grounded)

The price is slowly rising with the necessity of a higher rated MCU with a 3rd SPI port (for USB functionality) plus a USB-TTL module.

And there will be a bit of manual labour fitting the fifth pin in the link connector, cutting and grinding to make it pcb compatible. That will be up to the customer if they want to tackle it themselves or have me do it.

also going to embed the whole lot in polyurethane. I cant see any other reliable way to remove stress from the PCB-Connector infterface.

egr
Offline
Abandoned on Fire

I don't want to complicate unnecessarily but after posting my orginal ideas I realized that using a male link plug would make the device pretty much dmg-specific.  With that in mind, a female link plug would probably be more flexible since the user could source the appropriate cable for the gb model they use. Make sense or am I over thinking it?

Edit: looks like you may have already addressed this

Last edited by egr (Jan 18, 2015 3:21 am)

BennVenn
Offline
Australia

Sockets are too hard to come by so It will either be DMG or the Pocket/Colour size plug. Possibly both

egr
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Abandoned on Fire

Cool. Either works for me and less to carry.  smile

BennVenn
Offline
Australia

Almost completed the prototype!

I've gone with a 32Bit ARM processor, USB Mass storage mode on the PC side so no drivers and works on all Operating Systems.

I'm thinking of adding a Micro SD card socket for flash storage. This will make the Sav storage pretty much limitless! It does add complexity to the code as it is all pure assembly. I'll stick with an 8mb Flash IC for now.

egr
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Abandoned on Fire

Woot! Sounding great. MicroSD would be great but maybe overkill. 8mb will already hold over 60 savs which is a crazy huge amount smile

BennVenn
Offline
Australia

Firmware complete, PCB's in production!

I've gone with 30 'Slots' on the stick (Using a 4mbyte Flash IC - Can be upgraded to 64 slots with an additional 4mb IC) Each slot can be used to load/store an entire 128k cart save, can be renamed and duplicated via the gameboy and is accessed on the PC as a USB drive.

The most convenient backup utility yet?

Still need to work on the Gameboy side ROM, some nice GUI. I was hoping someone would offer assistance for this part of the project. Spare time is getting harder to find

egr
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Abandoned on Fire

If I were capable I'd definitely help. This looks to be the most useful non-cart related gameboy accessory ever created.

BennVenn
Offline
Australia

The boards have finally arrived! I'm leaning more towards the Link plug being 'flying' as in an inch or two of cable to relieve stress from the PCB and enclosure. This way I can use my existing Gen2 Low Profile enclosures too.

I've coded a very basic GB ROM, Load/Save/Slot# and a confirmation screen. I'll finish up the firmware on the block this weekend and hopefully have a working demo unit by next week.

egr
Offline
Abandoned on Fire

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