ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 287

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

27.8.11
27.8.12
9223B–AVR–09/11
Preventing Flash Corruption
Programming Time for Flash when Using SPM
During periods of low V
too low for the CPU and the Flash to operate properly. These issues are the same as for board
level systems using the Flash, and the same design solutions should be applied.
A Flash program corruption can be caused by two situations when the voltage is too low. First,
a regular write sequence to the Flash requires a minimum voltage to operate correctly. Sec-
ondly, the CPU itself can execute instructions incorrectly, if the supply voltage for executing
instructions is too low.
Flash corruption can easily be avoided by following these design recommendations (one is
sufficient):
The calibrated RC Oscillator is used to time Flash accesses.
gramming time for Flash accesses from the CPU.
Table 27-6.
Flash write (Page Erase, Page Write, and
write Lock bits by SPM)
Note:
1. If there is no need for a Boot Loader update in the system, program the Boot Loader
2. Keep the AVR RESET active (low) during periods of insufficient power supply voltage.
3. Keep the AVR core in Power-down sleep mode during periods of low V
Atmel ATmega48PA/88PA/168PA [Preliminary]
Lock bits to prevent any Boot Loader software updates.
This can be done by enabling the internal Brown-out Detector (BOD) if the operating
voltage matches the detection level. If not, an external low V
can be used. If a reset occurs while a write operation is in progress, the write opera-
tion will be completed provided that the power supply voltage is sufficient.
prevent the CPU from attempting to decode and execute instructions, effectively pro-
tecting the SPMCSR Register and thus the Flash from unintentional writes.
1. Minimum and maximum programming time is per individual operation.
SPM Programming Time
Symbol
CC
, the Flash program can be corrupted because the supply voltage is
(27.8.13)
Min. Programming Time
3.7ms
Table 27-6
CC
reset protection circuit
Max Programming Time
shows the typical pro-
CC
4.5ms
. This will
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