MC9S12E128CFUE Datasheet, PDF (102/606 Pages) Freescale Semiconductor, Inc – MC9S12E128 Data Sheet

Chapter 2 128 Kbyte Flash Module (FTS128K1V1)
Module Base + 0x000F
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 2-20. RESERVED6
All bits read 0 and are not writable.
2.4 Functional Description
2.4.1 Flash Command Operations
Write operations are used for the program, erase, and erase verify algorithms described in this section. The
program and erase algorithms are controlled by a state machine whose timebase FCLK is derived from the
oscillator clock via a programmable divider. The FCMD register as well as the associated FADDR and
FDATA registers operate as a buffer and a register (2-stage FIFO) so that a new command along with the
necessary data and address can be stored to the buffer while the previous command is still in progress. This
pipelined operation allows a time optimization when programming more than one word on a specific row,
as the high voltage generation can be kept active in between two programming commands. The pipelined
operation also allows a simplification of command launching. Buffer empty as well as command
completion are signalled by flags in the FSTAT register with corresponding interrupts generated, if
enabled.
The next sections describe:
• How to write the FCLKDIV register
• Command write sequence used to program, erase or erase verify the Flash array
• Valid Flash commands
• Errors resulting from illegal Flash operations
2.4.1.1 Writing the FCLKDIV Register
Prior to issuing any Flash command after a reset, it is first necessary to write the FCLKDIV register to
divide the oscillator clock down to within the 150-kHz to 200-kHz range. Since the program and erase
timings are also a function of the bus clock, the FCLKDIV determination must take this information into
account.
If we define:
• FCLK as the clock of the Flash timing control block
• Tbus as the period of the bus clock
• INT(x) as taking the integer part of x (e.g., INT(4.323) = 4),
MC9S12E128 Data Sheet, Rev. 1.07
102
Freescale Semiconductor