Texas Instruments MSP430x4xx - Manual (Page 144)

Flash Memory Registers
5-19 Flash Memory Controller
FCTL2, Flash Memory Control Register
15 14 13 12 11 10 9 8
FWKEYx, Read as 096h
Must be written as 0A5h
7 6 5 4 3 2 1 0
FSSELx FNx
rw−0 rw−1 rw-0 rw-0 rw-0 rw−0 rw-1 rw−0
FWKEYx Bits
15-8 FCTLx password. Always read as 096h. Must be written as 0A5h or a PUC
will be generated.
FSSELx Bits
7−6 Flash controller clock source select
00
ACLK
01 MCLK
10 SMCLK
11 SMCLK
FNx Bits
5-0 Flash controller clock divider. These six bits select the divider for the flash
controller clock. The divisor value is FNx + 1. For example, when FNx=00h,
the divisor is 1. When FNx=03Fh the divisor is 64.