ATTINY43U-MUR Atmel, ATTINY43U-MUR Datasheet - Page 52

• Manufacturer Part Number: ATTINY43U-MUR
• Description: MCU AVR 4KB FLASH 8MHZ 20QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY43U-MUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 64 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.8.1
9.8.1.1
52
ATtiny43U
Timed Sequences for Changing the Configuration of the Watchdog Timer
Safety Level 1
clock cycle periods can be selected to determine the reset period. If the reset period expires
without another Watchdog Reset, the ATtiny43U resets and executes from the Reset Vector.
For timing details on the Watchdog Reset, refer to
The Wathdog Timer can also be configured to generate an interrupt instead of a reset. This can
be very helpful when using the Watchdog to wake-up from Power-down.
To prevent unintentional disabling of the Watchdog or unintentional change of time-out period,
two different safety levels are selected by the fuse WDTON as shown in Table 9-1. See
Sequences for Changing the Configuration of the Watchdog Timer” on page 52
Table 9-1.
Figure 9-7.
The sequence for changing configuration differs slightly between the two safety levels. Separate
procedures are described for each level.
In this mode, the Watchdog Timer is initially disabled, but can be enabled by writing the WDE bit
to one without any restriction. A timed sequence is needed when disabling an enabled Watch-
dog Timer. To disable an enabled Watchdog Timer, the following procedure must be followed:
WDTON
Unprogrammed
Programmed
1. In the same operation, write a logic one to WDCE and WDE. A logic one must be writ-
2. Within the next four clock cycles, in the same operation, write the WDE and WDP bits
ten to WDE regardless of the previous value of the WDE bit.
as desired, but with the WDCE bit cleared.
WDT Configuration as a Function of the Fuse Settings of WDTON
Watchdog Timer
Safety
Level
WATCHDOG
1
2
OSCILLATOR
RESET
128 kHz
WDP0
WDP1
WDP2
WDP3
WDE
WDT Initial
State
Disabled
Enabled
How to Disable the
WDT
Timed sequence
Always enabled
Table 9-3 on page
MCU RESET
PRESCALER
WATCHDOG
56.
How to Change Time-
out
No limitations
Timed sequence
for details.
8048B–AVR–03/09
“Timed