MC9S12A256 Motorola, MC9S12A256 Datasheet - Page 105

• Manufacturer Part Number: MC9S12A256
• Description: MC9S12DT256 Device User Guide V03.03
• Manufacturer: Motorola

A.3 NVM, 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 f
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 f
The minimum program and erase times shown in Table A-11 are calculated for maximum f
maximum f
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
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.
NOTE:
bus
. The maximum times are calculated for minimum f
Unless otherwise noted the abbreviation NVM (Non Volatile Memory) is used for
both Flash and EEPROM.
NVMOP
NVMOSC
and can be calculated according to the following formula.
NVMOP
is required for performing program or erase operations. The NVM modules
.
t
t
swpgm
t
bwpgm
brpgm
=
=
=
9
t
4
swpgm
---------------------
f
---------------------
f
NVMOP
NVMOP
1
1
+
31 t
+
+
25
9
bwpgm
MC9S12DT256 Device User Guide V03.03
NVMOP
----------
f
----------
f
bus
bus
1
1
and a f
bus
of 2MHz.
NVMOP
and
103