Based on the design of Timmy Brolin´s hombrew flashcart i developed a 128MBit basic flashcart without SRAM or EEPROM (see fig. 1).
Why to build such a cart, if there are so many commercial and far better flashcartridges (with SRAM and EEPROM) are available? For me it were the following reasons:
So keep in mind, that this cart is not really cheaper than a commercially available one, but a good starting point for own development...
Fig. 1: View of the GBA flashcart
What is on the cart-PCB, can be seen in the schematic (pdf) and the placeplan (pdf). It is the same design, Timmy Brolin used (adress/data-demultiplexing with 74AC191 counters for random and sequential access), except that my cart uses a 128MBit Intel Strata Flash (TE28F128J3C120) and low-voltage single-gate-logic.
If you manage to get the board data (Eagle V4.13 format) on a 1mm (originally 0.8mm) thick PCB, the board fits perfectly in a original cart housing. Mine has a thickness of 1.5mm, so i have to do a bit extra work to get a suitable cart-housing.
As you can see in fig. 2, i used an old folded business card to do the first initiation of the prototype card, to fit properly into the cart-connector of the GBA.
Fig. 2: The flashcart plugged into the GBA SP
If you built a cart, the FLASH on it has to be programmed. What you need is a multiboot cable (e.g. a F2A USB Linker as i use. Maybe other MB-cables will work too...) and the apropriate programming software like Flashmanager V2.42 (local copy as sfx-zip) by Mootan (japanese page https://mootan.hg.to/fmgba).
This neat little shareware supports some multiboot cable types and nearly all available cart- and flash-types. Programming the FLASH is a bit slow but it works absolute reliable. So, don´t forget to donate this japanese guy and register the shareware.
In fig. 3 you can see a screenshot of the PD-game Arkanoid Advance by "Yodajr" running on my homemade flashcart.
If you have questions about the project, you are invited to contact me (see the Legal page).
Fig. 3: The PD-game Arkanoid running on the cart