ATmega88 Atmel Corporation, ATmega88 Datasheet - Page 53

• Manufacturer Part Number: ATmega88
• Manufacturer: Atmel Corporation

Specifications of ATmega88

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 24
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

11.9
11.9.1
11.9.2
2545T–AVR–05/11
Register description
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 Atmel 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 writ-
ing 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
ATmega48/88/168
R/W
2
0
2
WDP1
R/W
EXTRF
R/W
1
0
1
WDP0
R/W
PORF
0
0
R/W
0
WDTCSR
MCUSR
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