S12SCIV2SLASHD datasheet(103/130 Pages) FREESCALE

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MC9S12H256 Device User Guide — V01.18

A.3 NVM, Flash and EEPROM

NOTE:

Unless otherwise noted the abbreviation NVM (Non Volatile Memory) is used for

both Flash and EEPROM.

A.3.1 NVM timing

The time base for all NVM program or erase operations is derived from the oscillator. A minimum

oscillator frequency fNVMOSC is required for performing program or erase operations. The NVM modules

do not have any means to monitor the frequency and will not prevent program or erase operation at

frequencies above or below the specified minimum. Attempting to program or erase the NVM modules at

a lower frequency a full program or erase transition is not assured.

The Flash and EEPROM program and erase operations are timed using a clock derived from the oscillator

using the FCLKDIV and ECLKDIV registers respectively. The frequency of this clock must be set within

the limits specified as fNVMOP.

The minimum program and erase times shown in Table A-11 are calculated for maximum fNVMOP and

maximum fbus. The maximum times are calculated for minimum fNVMOP and a fbus of 2MHz.

A.3.1.1 Single Word Programming

The programming time for single word programming is dependant on the bus frequency as a well as on

the frequency fNVMOP and can be calculated according to the following formula.

A.3.1.2 Burst Programming

This applies only to the Flash where up to 32 words in a row can be programmed consecutively using burst

programming by keeping the command pipeline filled. The time to program a consecutive word can be

calculated as:

The time to program a whole row is:

Burst programming is more than 2 times faster than single word programming.

swpgm

NVMOP

---------------------

⋅

bus

----------

⋅

bwpgm

NVMOP

---------------------

⋅

bus

----------

⋅

brpgm

swpgm

31 t

bwpgm

⋅

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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