CS2 needs to be pulled up, otherwise data corruption in FRAM can occur during powerup. Most flashers have the cart pins in tri-state during powerup. The FM28V100 datasheet specifically describes the data corruption that will occur if the CE pins are not pulled up.
I have 2 ChisFlash cartridges with FRAM which always get corrupted if I simply plug them into a powered GBFlash (not programming, simply plugging in), or power the GBFlash with the cart plugged in. The same issue occurs on a BurnMaster.
The green LED in the cart seems to be driven by CPLD logic if CS2 is LOW. Every time the data corruption occurs - the green LED is also flashed.
I have soldered a 10k pullup between CS2 and VCC and the issue went away. The green LED stopped flashing during power cycles or plug cycles into flashers.
CS2 needs to be pulled up, otherwise data corruption in FRAM can occur during powerup. Most flashers have the cart pins in tri-state during powerup. The FM28V100 datasheet specifically describes the data corruption that will occur if the CE pins are not pulled up.
I have 2 ChisFlash cartridges with FRAM which always get corrupted if I simply plug them into a powered GBFlash (not programming, simply plugging in), or power the GBFlash with the cart plugged in. The same issue occurs on a BurnMaster.
The green LED in the cart seems to be driven by CPLD logic if CS2 is LOW. Every time the data corruption occurs - the green LED is also flashed.
I have soldered a 10k pullup between CS2 and VCC and the issue went away. The green LED stopped flashing during power cycles or plug cycles into flashers.