Техническая Спецификация для Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI
Модели
MEGA328P-XMINI
50
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
Figure 11-3.
MCU Start-up, RESET Extended Externally
11.4
External Reset
An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the minimum pulse
width (see
width (see
) will generate a reset, even if the clock is not
running. Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the Reset
Threshold Voltage – V
Threshold Voltage – V
RST
– on its positive edge, the delay counter starts the MCU after the Time-out period –
t
TOUT
–
has expired. The External Reset can be disabled by the RSTDISBL fuse, see
.
Figure 11-4.
External Reset During Operation
11.5
Brown-out Detection
ATmega48A/PA/88A/PA/168A/PA/328/P has an On-chip Brown-out Detection (BOD) circuit for monitoring the
V
V
CC
level during operation by comparing it to a fixed trigger level. The trigger level for the BOD can be selected
by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure spike free Brown-out Detection. The
hysteresis on the detection level should be interpreted as V
hysteresis on the detection level should be interpreted as V
BOT+
= V
BOT
+ V
HYST
/2 and V
BOT-
= V
BOT
-
V
HYST
/2.When the BOD is enabled, and V
CC
decreases to a value below the trigger level (V
BOT-
in
), the Brown-out Reset is immediately activated. When V
CC
increases above the trigger level (V
BOT+
in
), the delay counter starts the MCU after the Time-out period t
TOUT
has expired.
The BOD circuit will only detect a drop in V
CC
if the voltage stays below the trigger level for longer than t
BOD
.
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
V
CC
CC