Is it possible to use flash memory to store data?

Writing stuff to flash is not a good idea.

I have to do it on a silabs 8051 in a system that has no other way to store items.
In the case of this part, you have to go through some gyrations to open the flash for writing.
BUT this risks corrupting flash that you are running code in.

As it turned out the product has been experiencing random flash corruption. It took a very very
long time to find the reason. like a couple of years.

Essentially on the 8051, if you disable the interrupt mask with EA=0; unless the next instruction is a EA=0 instruction, you can get an interrupt.

In my case, I found quite by accident that my sequence was allowing an interrupt to happen between the EA=0, and after the redirection bit was set, so the interrupt would run with
flash open to writing. It happened rarely, but we finally got a device that did it repeatedly for some reason, and got it to happen with an unprotected flash load, and I was able to track it down.

So IF you write to flash, be very very careful of things like this.

Writing stuff to flash is not a good idea.

I have to do it on a silabs 8051 in a system that has no other way to store items.
In the case of this part, you have to go through some gyrations to open the flash for writing.
BUT this risks corrupting flash that you are running code in.

As it turned out the product has been experiencing random flash corruption. It took a very very
long time to find the reason. like a couple of years.

Essentially on the 8051, if you disable the interrupt mask with EA=0; unless the next instruction is a EA=0 instruction, you can get an interrupt.

In my case, I found quite by accident that my sequence was allowing an interrupt to happen between the EA=0, and after the redirection bit was set, so the interrupt would run with
flash open to writing. It happened rarely, but we finally got a device that did it repeatedly for some reason, and got it to happen with an unprotected flash load, and I was able to track it down.

So IF you write to flash, be very very careful of things like this.

... flash has limited 'wear'. in the datasheet you will find a number of erase cycles that flash can 'endure' when you pass that you have no guarantee that the write will be succesful. Also you can not just write to a flash, the page must be erased first