to start im new here and have very little experience in this so please bear with me. what im looking to do is design and implement device that takes place of eproms in an car ECU allowing them to be flashed over USB. the one atmel device i discovered that lead me here is the AT90USB646 so thats why im here. the thing here is i need to essentially flash 2 different eeproms as the cars computer has 2 separate processors and eeproms so i need a way to differentiate where one flash belongs instead of flashing both with the same data. the second idea is to have one large flash and a way to sort of split it in half somehow between both sides of the ECU. yes i want to get rid of eproms and use surface mount flash chips because im limited on space.
now the other problem here is the one chip because its an 87c257 latched eprom stock and a standard 27c256 does not work at all on it without a special adapter. in the past i have used a 74HC373 tri state latch to adapt that side to allow the use of standard 27c256 chips or SST27SF512 EEPROMS. so with that information would be be possible to put the 74HC373 in line as usual with a flash on that side than when the flash itself needs programmed flash it on the back side before the 74HC373 latch and pray that the latch being in circuit doesnt affect the flashing process? yes i know this is a lot for a first timer. any insight would be great. thanks.