ATmega8HVA Atmel Corporation, ATmega8HVA Datasheet - Page 47

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ATmega8HVA

Manufacturer Part Number
ATmega8HVA
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of ATmega8HVA

Flash (kbytes)
8 Kbytes
Pin Count
28
Max. Operating Frequency
4 MHz
Cpu
8-bit AVR
# Of Touch Channels
3
Hardware Qtouch Acquisition
No
Max I/o Pins
6
Ext Interrupts
3
Usb Speed
No
Usb Interface
No
Spi
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
6
Adc Resolution (bits)
12
Adc Speed (ksps)
1.9
Resistive Touch Screen
No
Temp. Sensor
Yes
Crypto Engine
No
Sram (kbytes)
0.5
Eeprom (bytes)
256
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-20 to 85
I/o Supply Class
1.8 to 9.0
Operating Voltage (vcc)
1.8 to 9.0
Fpu
No
Mpu / Mmu
no / no
Timers
2
Output Compare Channels
4
Input Capture Channels
2
32khz Rtc
No
Calibrated Rc Oscillator
Yes
8024A–AVR–04/08
1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE) and
2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP) as
The following code example shows one assembly and one C function for turning off the Watch-
dog Timer. The example assumes that interrupts are controlled (e.g. by disabling interrupts
globally) so that no interrupts will occur during the execution of these functions.
Note:
Assembly Code Example
C Code Example
WDE. A logic one must be written to WDE regardless of the previous value of the WDE
bit.
desired, but with the WDCE bit cleared. This must be done in one operation.
WDT_off:
void WDT_off(void)
{
*/
}
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Clear WDRF in MCUSR
in
andi
out
; Write logical one to WDCE and WDE
; Keep old prescaler setting to prevent unintentional time-out
in
ori
out
; Turn off WDT
ldi
out
; Turn on global interrupt
sei
ret
__disable_interrupt();
__watchdog_reset();
/* Clear WDRF in MCUSR */
MCUSR &= ~(1<<WDRF);
/* Write logical one to WDCE and WDE */
/* Keep old prescaler setting to prevent unintentional time-out
WDTCSR |= (1<<WDCE) | (1<<WDE);
/* Turn off WDT */
WDTCSR = 0x00;
__enable_interrupt();
1. See “About Code Examples” on page 7.
r16, MCUSR
r16, (0xff & (0<<WDRF))
MCUSR, r16
r16, WDTCSR
r16, (1<<WDCE) | (1<<WDE)
WDTCSR, r16
r16, (0<<WDE)
WDTCSR, r16
(1)
(1)
ATmega8HVA/16HVA
47

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