C8051F336/7/8/9
viced in priority order after the Flash operation has been completed and interrupts have been
re-enabled by software.
10. Make certain that the Flash write and erase pointer variables are not located in XRAM. See
your compiler documentation for instructions regarding how to explicitly locate variables in dif-
ferent memory areas.
11. Add address bounds checking to the routines that write or erase Flash memory to ensure that
a routine called with an illegal address does not result in modification of the Flash.
16.4.3. System Clock
12. If operating from an external crystal, be advised that crystal performance is susceptible to
electrical interference and is sensitive to layout and to changes in temperature. If the system is
operating in an electrically noisy environment, use the internal oscillator or use an external
CMOS clock.
13. If operating from the external oscillator, switch to the internal oscillator during Flash write or
erase operations. The external oscillator can continue to run, and the CPU can switch back to
the external oscillator after the Flash operation has completed.
Additional Flash recommendations and example code can be found in AN201, "Writing to Flash from Firm-
ware", available from the Silicon Laboratories web site.
Rev. 0.2
103
SILICON [ SILICON ]
