Texas Instruments MSP430x1xx User Manual
Page 427
Flash Memory Control Registers
C-15
Flash Memory
C.3.2 Flash Memory Control Register FCTL2
A PUC resets the flash timing generator. The generator is also reset if the
emergency exit bit EMEX is set.
The timing generator generates the timing necessary to write, erase, and
mass-erase from a selected clock source. Two control bits SSEL0 and SSEL1
in control register FCTL2 can select one of three clock sources. The clock
source selected should be divided to meet the frequency requirements for f
x
,
as specified in the device’s data sheet.
Writing to control register FCTL2 should not be attempted if the BUSY bit is set;
otherwise an access violation will occur (ACCVIFG=1). Read access to FCTL2
is possible at any time without restrictions.
7
0
rw–0 rw–1 rw–0 rw–0 rw–0 rw–0 rw–1 rw–0
012Ah
FCTL2
SSEL1
15
8
FCTL2 read:
FCTL2 write:
0 9 6 h
0 A 5 h
SSEL0 FN5
FN4
FN3
FN2
FN1
FN0
The control bits are:
FN0
to
012Ah, bit0,
These six bits define the division rate of the clock signal. The division
rate can be 1 to 64, depending on the digital value of FN5 to FN0
FN5
012Ah, bit5,
plus one
SSEL0
012Ah, bit0,
Determine the clock source.
SSEL1
0:
ACLK
1:
MCLK
2,3 SMCLK