Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI 数据表
产品代码
MEGA328P-XMINI
259
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
26.2.3 Preventing Flash Corruption
During periods of low V
CC
, the Flash program can be corrupted because the supply voltage is 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.
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. Secondly, the CPU itself can execute
instructions incorrectly, if the supply voltage for executing instructions is too low.
sequence to the Flash requires a minimum voltage to operate correctly. Secondly, 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):
1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage. 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
not, an external low V
CC
reset protection circuit can be used. If a reset occurs while a write operation is in
progress, the write operation will be completed provided that the power supply voltage is sufficient.
2.
Keep the AVR core in Power-down sleep mode during periods of low V
CC
. This will prevent the CPU from
attempting to decode and execute instructions, effectively protecting the SPMCSR Register and thus the
Flash from unintentional writes.
Flash from unintentional writes.
26.2.4 Programming Time for Flash when Using SPM
The calibrated RC Oscillator is used to time Flash accesses.
Flash accesses from the CPU.
Note:
1.
Minimum and maximum programming time is per individual operation.
Table 26-1.
SPM Programming Time
Symbol
Min. Programming Time
Max Programming Time
Flash write (Page Erase, Page Write, and
write Lock bits by SPM)
write Lock bits by SPM)
3.7ms
4.5ms