Texas Instruments MSP430x1xx - Manual (Page 424)

Flash Memory Data Structure and Operation
C-12
The write cycle is successfully completed if none of the following restrictions
is violated:
- The selected clock source is available until the cycle is completed.
- The predivider is not modified.
- The access to the flash memory module is restricted as long as BUSY is
set.
The conditions to read data from the flash memory with and without access
violation are listed in Table C–2.
Table C–2. Conditions to Read Data From Flash Memory
Flash Operation Instruction
Fetch
(see Note 1)
BUSY WAIT Data on Memory Data
Bus (MDB)
Action
Byte/word program
cycle (see Note 2) No 1 0 3FFF Access violation
Yes 1 0 3FFF
→
JMP $ Nothing
Flash read mode 0 0 Memory contents from
applied address PC = PC + 2
Page erase cycle
(see Note 3) No 1 0 3FFF Access violation
Yes 1 0 3FFF
→
JMP $ Nothing
Mass-erase cycle
(see Note 3) No 1 0 3FFF Access violation
Yes 1 0 3FFF
→
JMP $ Nothing
All erase (mass and in-
formation memory) No 1 0 3FFF Access violation
Yes 1 0 3FFF
→
JMP $ Nothing
Segment write
(see Note 4) N.A. 1 0 3FFF Access violation and
LOCK (see Note 5)
No 1 1 3FFF Nothing
Yes 1 1 3FFF Access violation and
LOCK (see Note 5)
Notes: 1) Instruction fetch refers to the fetch part of an instruction, and reads one word. The instruction fetch reads the first
word of instructions with more than one word. The JMP instruction has one word. The data fetched (3FFFh) is used
by the CPU as an instruction.
2) Ensure that the programmed data does not result in unpredictable program execution, such as destruction of
executable code sequences.
3) If the PC points to the memory location being erased, no access violation indicates this situation. After erase, no
executable code is available and an unpredictable situation occurs.
4) Any software located in a flash memory module can not use the SEGWRT mode to program the same flash memory
module. Using the byte or word programming mode allows programming data in the flash memory module holding
the software code currently executing.
5) The access violation sets the LOCK bit to 1. Setting the LOCK bit allows completion of the active segment write
operation in the normal manner.