WonderSwan Development Cartridge
Short Summary
This project allows a Wonderswan developer to upload 64 kB of code/data and execute it on real Wonderswan handheld gaming hardware.
Long Summary
We started by opening up one of our Wonderswan cartridges and identifying the various chips and circuitry found inside. We found the main ROM chip, and guessed that it would follow standard JEDEC pinouts for programmable ROM chips of this nature. Having a nonstandard pinout would've increased production costs. We then mapped the pins on the cartridge edge connector to the pins on the ROM chip, so we had a rough idea of what type of chip it was and how the address and data lines were connected.
After verifying possibility of success, we proceeded to build a memory programmer. Since the Wonderswan uses a 16bit wide word data bus, we purchased two SRAM chips, each 8bit wide. We then chained these together to provide a total of 32768 16bit words over a 15bit address space. Since the Wonderswan and our MCU operated on different voltages and we didn't have enough pins on the MCU to directly address all 31 lines and still be able to communicate over a serial line, we built a demultiplexer circuit out of 74AHC logic family chips. This allowed us to buffer out the various lines over time, and also allowed us to drive a 3.3V output level chip with 5V signals.
After the hardware was built, we programmed on the MCU a XModemCRC compatible transfer program so that we can both upload and download from our "cartridge."
In order to interface with the Wonderswan, we etched our own board using a laser toner transfer method, and trimmed it so that it fit into the cartridge slot on the Wonderswan. After everything was attached, we realized that the Wonderswan had a hardware handshake to check for valid cartridges. A valid cartridge has a custom chip, which we could not reproduce. Thus, we tricked the Wonderswan into accepting our cartridge by booting into its preferences mode (which needs a cartridge to load up but doesn't run off the cartridge), and then inserting our cartridge and letting the mode continue to normal play.
Link: http://instruct1.cit.cornell.edu/courses/e...zz25/index.html
Short Summary
This project allows a Wonderswan developer to upload 64 kB of code/data and execute it on real Wonderswan handheld gaming hardware.
Long Summary
We started by opening up one of our Wonderswan cartridges and identifying the various chips and circuitry found inside. We found the main ROM chip, and guessed that it would follow standard JEDEC pinouts for programmable ROM chips of this nature. Having a nonstandard pinout would've increased production costs. We then mapped the pins on the cartridge edge connector to the pins on the ROM chip, so we had a rough idea of what type of chip it was and how the address and data lines were connected.
After verifying possibility of success, we proceeded to build a memory programmer. Since the Wonderswan uses a 16bit wide word data bus, we purchased two SRAM chips, each 8bit wide. We then chained these together to provide a total of 32768 16bit words over a 15bit address space. Since the Wonderswan and our MCU operated on different voltages and we didn't have enough pins on the MCU to directly address all 31 lines and still be able to communicate over a serial line, we built a demultiplexer circuit out of 74AHC logic family chips. This allowed us to buffer out the various lines over time, and also allowed us to drive a 3.3V output level chip with 5V signals.
After the hardware was built, we programmed on the MCU a XModemCRC compatible transfer program so that we can both upload and download from our "cartridge."
In order to interface with the Wonderswan, we etched our own board using a laser toner transfer method, and trimmed it so that it fit into the cartridge slot on the Wonderswan. After everything was attached, we realized that the Wonderswan had a hardware handshake to check for valid cartridges. A valid cartridge has a custom chip, which we could not reproduce. Thus, we tricked the Wonderswan into accepting our cartridge by booting into its preferences mode (which needs a cartridge to load up but doesn't run off the cartridge), and then inserting our cartridge and letting the mode continue to normal play.
Link: http://instruct1.cit.cornell.edu/courses/e...zz25/index.html