mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 585

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

All bits in the FRSV4 register read 0 and are not writable.
19.4
19.4.1
Flash command operations are used to modify Flash memory contents.
The next sections describe:
19.4.1.1
Prior to issuing any Flash program or erase command after a reset, the user is required to write the
FCLKDIV register to divide OSCCLK down to a target FCLK of 1 MHz.
values for the FDIV field based on OSCCLK frequency.
When the FCLKDIV register is written, the FDIVLD bit is set automatically. If the FDIVLD bit is 0, the
FCLKDIV register has not been written since the last reset. If the FCLKDIV register has not been written,
any Flash program or erase command loaded during a command write sequence will not execute and the
ACCERR bit in the FSTAT register will set.
Freescale Semiconductor
Offset Module Base + 0x0013
Reset
•
•
•
W
R
How to write the FCLKDIV register that is used to generate a time base (FCLK) derived from
OSCCLK for Flash program and erase command operations
The command write sequence used to set Flash command parameters and launch execution
Valid Flash commands available for execution
Functional Description
Flash Command Operations
Writing the FCLKDIV Register
0
0
7
Programming or erasing the Flash memory cannot be performed if the bus
clock runs at less than 1 MHz. Setting FDIV too high can destroy the Flash
memory due to overstress. Setting FDIV too low can result in incomplete
programming or erasure of the Flash memory cells.
= Unimplemented or Reserved
0
0
6
Figure 19-25. Flash Reserved4 Register (FRSV4)
S12XS Family Reference Manual, Rev. 1.10
0
0
5
NOTE
0
0
4
0
0
3
128 KByte Flash Module (S12XFTMR128K1V1)
Table 19-7
0
0
2
shows recommended
0
0
1
0
0
0
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