Datasheet
Table Of Contents
- List of Sections
- Table of Contents
- General Description
- Central Processing Unit (CPU)
- Pinout and Signal Description
- System Configuration
- Registers
- Operating Modes
- Resource Mapping
- Bus Control and Input/Output
- Resets and Interrupts
- Voltage Regulator (VREG)
- Flash EEPROM 256K
- EEPROM 4K
- Port Integration Module
- Clocks and Reset Generator (CRG)
- Pulse Width Modulator (PWM)
- Enhanced Capture Timer (ECT)
- Serial Communications Interface (SCI)
- Serial Peripheral Interface (SPI)
- Inter-IC Bus (IIC)
- MSCAN
- Analog to Digital Converter
- Byte Data Link Controller Module
- Contents
- Overview
- Features
- Block Diagram
- Register Map
- Functional Description
- Register Descriptions
- External Pin Descriptions
- Reset Initialization/Basic Operation
- Transmitting A Message
- Receiving A Message
- Transmitting An In-Frame Response (IFR)
- Receiving An In-Frame Response (IFR)
- Special BDLC Operations
- Modes of Operation
- Interrupt Operation
- Low Power Options
- Background Debug Module (BDM)
- Breakpoint (BKP) Module
- Revision History
- Glossary
- Literature Updates

Flash EEPROM 256K
MC9S12DP256 — Revision 1.1
Flash EEPROM 256K
FDIV[5:0] — Flash Clock Divider
The combination of FDIV8 and FDIV[5:0] is used to divide the
oscillator clock down to a frequency of 150KHz - 200KHz. This
resulting clock, FCLK, is used to drive the program and erase state
machines for the flash.
For frequencies of OSCCLK > 12.8MHz the Prescaler bit FDIV8 must
be turned on.
FCLKDIV must be chosen such that the following equation is valid.
If FDIV8 == 1 then CLK = OSCCLK / 8, else CLK = OSCCLK
FCLKDIV = INT (CLK[KHz] / 200KHz)
The clock to the flash timing control is therefore:
FCLK = CLK / (FDIV[5:0] + 1)
150KHz < FCLK <= 200KHz
For example, if OSCCLK = 950KHz, FCLKDIV should be set to 4 and
FDIV8 set to 0. The resulting FCLK is 190KHz. As a result the flash
timings are increased by:
(200 - 190) / 200 x 100% = 5%
Remark: INT means rounding towards 0.
Example: INT(950KHz/200KHz) = 4.
WARNING:
Programming the flash with OSCCLK < 500KHz should be avoided.
Setting FCLKDIV to a value such that FCLK < 150KHz can destroy
the flash due to overstress. Setting FCLKDIV to a value such that
FCLK > 200KHz can result in improperly programmed memory
cells.
NOTE:
Command execution time will increase proportionally with the period of
FCLK.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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