Hi Roelf,

Forget trying to write to the 4051's flash. A serial eeprom is easy to connect if you need some ee storage. Two or three port pins and an 8 pin part.

Ok so it is external, but you'll either have to use external parts or a different uC.

If you're storing any kind of rapidly changing data, you'll more likely run into flash write life limitations even if you could write to flash via some bootloader code.

Dennis