ATMEGA48-20MI Atmel, ATMEGA48-20MI Datasheet - Page 52

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ATMEGA48-20MI

Manufacturer Part Number
ATMEGA48-20MI
Description
IC AVR MCU 4K 5V 20MHZ 32-QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA48-20MI

Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
23
Program Memory Size
4KB (2K x 16)
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
ATMEGA48-24MI
ATMEGA48-24MI
10.9
10.9.1
10.9.2
52
Register Description
ATmega48/88/168
MCUSR – MCU Status Register
WDTCSR – Watchdog Timer Control Register
The MCU Status Register provides information on which reset source caused an MCU reset.
• Bit 7..4: Res: Reserved Bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
• Bit 3 – WDRF: Watchdog System Reset Flag
This bit is set if a Watchdog System Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to the flag.
To make use of the Reset Flags to identify a reset condition, the user should read and then
Reset the MCUSR as early as possible in the program. If the register is cleared before another
reset occurs, the source of the reset can be found by examining the Reset Flags.
• Bit 7 - WDIF: Watchdog Interrupt Flag
This bit is set when a time-out occurs in the Watchdog Timer and the Watchdog Timer is config-
ured for interrupt. WDIF is cleared by hardware when executing the corresponding interrupt
handling vector. Alternatively, WDIF is cleared by writing a logic one to the flag. When the I-bit in
SREG and WDIE are set, the Watchdog Time-out Interrupt is executed.
• Bit 6 - WDIE: Watchdog Interrupt Enable
When this bit is written to one and the I-bit in the Status Register is set, the Watchdog Interrupt is
enabled. If WDE is cleared in combination with this setting, the Watchdog Timer is in Interrupt
Mode, and the corresponding interrupt is executed if time-out in the Watchdog Timer occurs.
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
(0x60)
Read/Write
Initial Value
WDIF
R/W
7
0
R
7
0
WDIE
R/W
6
0
R
6
0
WDP3
R/W
5
0
R
5
0
WDCE
R/W
4
0
R
4
0
WDE
WDRF
R/W
R/W
3
X
3
WDP2
R/W
BORF
See Bit Description
R/W
2
0
2
WDP1
R/W
EXTRF
1
0
R/W
1
WDP0
R/W
PORF
0
0
R/W
0
2545S–AVR–07/10
WDTCSR
MCUSR

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