MC9S12DT128B Device User Guide — V01.07

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-11are 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 f¨NVMOP and can be calculated according to the following formula.

tswpgm = 9

---------------------1

+ 25

---------1-

 

fNVMOP

 

fbus

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:

tbwpgm = 4

---------------------1

+ 9

---------1-

 

fNVMOP

 

fbus

The time to program a whole row is:

tbrpgm = tswpgm + 31 tbwpgm

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

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Motorola MC9S12DB128B, MC9S12DT128B manual NVM, Flash and Eeprom, NVM timing, Single Word Programming, Burst Programming