Motorola MC9S12GC-Family - Manual (Page 105)

Device User Guide — 9S12C128DGV1/D V01.05
105
B.5 NVM, Flash and EEPROM
B.5.1 NVM timing
The time base for all NVM program or erase operations is derived from the oscillator. A minimum
oscillator frequency f
NVMOSC
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 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
NVMOP
.
The minimum program and erase times shown in Table B-8 are calculated for maximum f
NVMOP
and
maximum f
bus
. The maximum times are calculated for minimum f
NVMOP
and a f
bus
of 2MHz.
B.5.1.1 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.
B.5.1.2 Row Programming
Generally the time to program a consecutive word can be calculated as:
For the C16, GC16, C32 and GC32 device flash arrays, where up to 32 words in a row can be programmed
consecutively by keeping the command pipeline filled, the time to program a whole row is:
For the C64, GC64, C96, C128 and GC128 device flash arrays, where up to 64 words in a row can be
programmed consecutively by keeping the command pipeline filled, the time to program a whole row is:
Row programming is more than 2 times faster than single word programming.
t
swpgm
9
1
f
NVMOP
---------------------
⋅
25
1
f
bus
----------
⋅
+ =
t
bwpgm
4
1
f
NVMOP
---------------------
⋅
9
1
f
bus
----------
⋅
+ =
t
brpgm
t
swpgm
31 t
bwpgm
⋅
+ =
t
brpgm
t
swpgm
63 t
bwpgm
⋅
+ =