ATTINY20-MMHR Atmel, ATTINY20-MMHR Datasheet - Page 37

• Manufacturer Part Number: ATTINY20-MMHR
• Description: MCU AVR 2KB FLASH 12MHZ 20QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY20-MMHR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 12MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 12
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

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
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