Hi Nguyen,

yes, it is possible and works excellent.

I use it in many older designs, where no internal Flash exist, which can be updated in the application.


There are only two points to pay attention:

1.
The lock bits must leave unprogrammed

2.
The code which change the EA pin must be located in this address range, where the state of EA was dont care and always the external code memory was addressed, e.g. 0FF00h.


Peter