C8051F310/1/2/3/4/5/6/7
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.
10.4.3. 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.
SFR Definition 10.1. PSCTL: Program Store R/W Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
Bit7
-
Bit6
-
Bit5
-
Bit4
-
Bit3
-
Bit2
PSEE
Bit1
PSWE
Bit0
00000000
SFR Address:
0x8F
Bits7–2: UNUSED: Read = 000000b, Write = don’t care.
Bit1:
PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memory
to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the loca-
tion addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
Bit0:
PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash program memory disabled.
1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash
memory.
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SILABS [ SILICON LABORATORIES ]
