mc9s12vr48 Freescale Semiconductor, Inc, mc9s12vr48 Datasheet - Page 485

• Manufacturer Part Number: mc9s12vr48
• Description: S12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

17.4.3
IFR is an internal NVM resource readable by CPU , when NVMRES is active. The IFR fields are shown
in
The NVMRES global address map is shown in
17.4.4
Flash command operations are used to modify Flash memory contents.
The next sections describe:
17.4.4.1
Prior to issuing any Flash program or erase command after a reset, the user is required to write the
FCLKDIV register to divide BUSCLK down to a target FCLK of 1 MHz.
values for the FDIV field based on BUSCLK 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.
17.4.4.2
The Memory Controller will launch all valid Flash commands entered using a command write sequence.
Freescale Semiconductor
Table
•
•
•
•
VERNUM: Version number. The first version is number 0b_0001 with both 0b_0000 and 0b_1111
meaning ‘none’.
How to write the FCLKDIV register that is used to generate a time base (FCLK) derived from
BUSCLK 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, according to MCU functional mode and MCU
security state.
17-4.
Internal NVM resource (NVMRES)
Flash Command Operations
Writing the FCLKDIV Register
Command Write Sequence
Programming or erasing the Flash memory cannot be performed if the bus
clock runs at less than 0.8 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.
MC9S12VR Family Reference Manual, Rev. 2.2
Preliminary - Subject to Change Without Notice
Table 17-25. IFR Version ID Fields
Reserved
[15:4]
Table
NOTE
17-5.
VERNUM
[3:0]
64 KByte Flash Module (S12FTMRG64K512V1)
Table 17-7
shows recommended
485