ATMEGA328P-20PU Atmel, ATMEGA328P-20PU Datasheet - Page 278

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ATMEGA328P-20PU

Manufacturer Part Number
ATMEGA328P-20PU
Description
Manufacturer
Atmel
Datasheet

Specifications of ATMEGA328P-20PU

Cpu Family
ATmega
Device Core
AVR
Device Core Size
8b
Frequency (max)
20MHz
Interface Type
SPI/TWI/USART
Program Memory Type
Flash
Program Memory Size
32KB
Total Internal Ram Size
2KB
# I/os (max)
23
Number Of Timers - General Purpose
3
Operating Supply Voltage (typ)
3.3/5V
Operating Supply Voltage (max)
5.5V
Operating Supply Voltage (min)
2.7V
On-chip Adc
6-chx10-bit
Instruction Set Architecture
RISC
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Through Hole
Pin Count
28
Package Type
PDIP
Lead Free Status / Rohs Status
Compliant
26.6
8025K–AVR–10/09
Entering the Boot Loader Program
Table 26-2.
Note:
Table 26-3.
Note:
Entering the Boot Loader takes place by a jump or call from the application program. This may
be initiated by a trigger such as a command received via USART, or SPI interface. Alternatively,
the Boot Reset Fuse can be programmed so that the Reset Vector is pointing to the Boot Flash
start address after a reset. In this case, the Boot Loader is started after a reset. After the applica-
tion code is loaded, the program can start executing the application code. Note that the fuses
cannot be changed by the MCU itself. This means that once the Boot Reset Fuse is pro-
grammed, the Reset Vector will always point to the Boot Loader Reset and the fuse can only be
changed through the serial or parallel programming interface.
Table 26-4.
Note:
BLB0 Mode
BLB1 Mode
BOOTRST
1
2
3
4
1
2
3
4
1
0
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
Boot Lock Bit0 Protection Modes (Application Section)
Boot Lock Bit1 Protection Modes (Boot Loader Section)
Boot Reset Fuse
BLB02
BLB12
Reset Address
Reset Vector = Application Reset (address 0x0000)
Reset Vector = Boot Loader Reset (see
1
1
0
0
1
1
0
0
BLB01
BLB11
1
0
0
1
1
0
0
1
(1)
Protection
No restrictions for SPM or LPM accessing the Application
section.
SPM is not allowed to write to the Application section.
SPM is not allowed to write to the Application section, and LPM
executing from the Boot Loader section is not allowed to read
from the Application section. If Interrupt Vectors are placed in
the Boot Loader section, interrupts are disabled while executing
from the Application section.
LPM executing from the Boot Loader section is not allowed to
read from the Application section. If Interrupt Vectors are placed
in the Boot Loader section, interrupts are disabled while
executing from the Application section.
Protection
No restrictions for SPM or LPM accessing the Boot Loader
section.
SPM is not allowed to write to the Boot Loader section.
SPM is not allowed to write to the Boot Loader section, and LPM
executing from the Application section is not allowed to read
from the Boot Loader section. If Interrupt Vectors are placed in
the Application section, interrupts are disabled while executing
from the Boot Loader section.
LPM executing from the Application section is not allowed to
read from the Boot Loader section. If Interrupt Vectors are
placed in the Application section, interrupts are disabled while
executing from the Boot Loader section.
ATmega48P/88P/168P
Table 26-7 on page
(1)
(1)
286)
278

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