ATTINY43U-SUR Atmel, ATTINY43U-SUR Datasheet - Page 53

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

Specifications of ATTINY43U-SUR

• 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

9.8.1.2
9.8.2
8048B–AVR–03/09
Code Example
Safety Level 2
In this mode, the Watchdog Timer is always enabled, and the WDE bit will always read as one. A
timed sequence is needed when changing the Watchdog Time-out period. To change the
Watchdog Time-out, the following procedure must be followed:
The following code example shows one assembly and one C function for turning off the WDT.
The example assumes that interrupts are controlled (e.g., by disabling interrupts globally) so that
no interrupts will occur during execution of these functions.
Note:
Assembly Code Example
C Code Example
1. In the same operation, write a logical one to WDCE and WDE. Even though the WDE
2. Within the next four clock cycles, in the same operation, write the WDP bits as desired,
WDT_off:
void WDT_off(void)
{
}
always is set, the WDE must be written to one to start the timed sequence.
but with the WDCE bit cleared. The value written to the WDE bit is irrelevant.
wdr
; Clear WDRF in MCUSR
ldi
out
; Write logical one to WDCE and WDE
; Keep old prescaler setting to prevent unintentional Watchdog Reset
in
ori r16, (1<<WDCE)|(1<<WDE)
out WDTCR, r16
; Turn off WDT
ldi r16, (0<<WDE)
out WDTCR, r16
ret
_WDR();
/* Clear WDRF in MCUSR */
MCUSR = 0x00
/* Write logical one to WDCE and WDE */
WDTCR |= (1<<WDCE) | (1<<WDE);
/* Turn off WDT */
WDTCR = 0x00;
1. See
r16, WDTCR
r16, (0<<WDRF)
MCUSR, r16
“Code Examples” on page
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