ATtiny20 Atmel Corporation, ATtiny20 Datasheet - Page 37

• Manufacturer Part Number: ATtiny20
• Manufacturer: Atmel Corporation

Specifications of ATtiny20

• Flash (kbytes): 2 Kbytes
• Pin Count: 14
• Max. Operating Frequency: 12 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 5
• Hardware Qtouch Acquisition: Yes
• Max I/o Pins: 12
• Ext Interrupts: 12
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Self Program Memory: NO
• 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: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8.5.2
8235B–AVR–04/11
RSTFLR – Reset Flag Register
Table 8-3.
The Reset Flag Register provides information on which reset source caused an MCU Reset.
• Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read as zero.
• Bit 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog 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 RSTFLR 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
0x3B
Read/Write
Initial Value
WDP3
1
1
1
1
1
1
WDP2
0
0
1
1
1
1
Watchdog Timer Prescale Select (Continued)
R
7
–
0
WDP1
1
1
0
0
1
1
R
6
–
0
WDP0
0
1
0
1
0
1
R
5
–
0
R
4
–
0
WDT Oscillator Cycles
WDRF
Number of
R/W
X
3
BORF
R/W
X
2
Reserved
EXTRF
R/W
X
1
PORF
R/W
Typical Time-out
X
0
at V
ATtiny20
CC
RSTFLR
= 5.0V
37