ATmega16HVB Atmel Corporation, ATmega16HVB Datasheet - Page 50

• Manufacturer Part Number: ATmega16HVB
• Manufacturer: Atmel Corporation

Specifications of ATmega16HVB

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 17
• Ext Interrupts: 15
• 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): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

50
ATmega16HVB/32HVB
• Bit 6 – WDIE: Watchdog Interrupt Enable
When this bit is written to one and the I-bit in the Status Register is set, the Watchdog Interrupt is
enabled. If WDE is cleared in combination with this setting, the Watchdog Timer is in Interrupt
Mode, and the corresponding interrupt is executed if time-out in the Watchdog Timer occurs.
If WDE is set, the Watchdog Timer is in Interrupt and System Reset Mode. The first time-out in
the Watchdog Timer will set WDIF. Executing the corresponding interrupt vector will clear WDIE
and WDIF automatically by hardware (the Watchdog goes to System Reset Mode). This is use-
ful for keeping the Watchdog Timer security while using the interrupt. To stay in Interrupt and
System Reset Mode, WDIE must be set after each interrupt. This should however not be done
within the interrupt service routine itself, as this might compromise the safety-function of the
Watchdog System Reset mode. If the interrupt is not executed before the next time-out, a Sys-
tem Reset will be applied.
Table 11-1.
Note:
• Bit 5, 2:0 – WDP3:0 : Watchdog Timer Prescaler three, two, one, and null
The WDP3..0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is
enabled. The different prescaling values and their corresponding Timeout Periods are shown in
Table 11-2 on page
• Bit 4 – WDCE: Watchdog Change Enable
This bit is used in timed sequences for changing WDE and prescaler bits. To clear the WDE bit,
and/or change the prescaler bits, WDCE must be set.
Once written to one, hardware will clear WDCE after four clock cycles.
• Bit 3 – WDE: Watchdog System Reset Enable
WDE is overridden by WDRF in MCUSR. This means that WDE is always set when WDRF is
set. To clear WDE, WDRF must be cleared first. This feature ensures multiple resets during con-
ditions causing failure, and a safe start-up after the failure.
• Bits 5, 2:0 – WDP3:0: Watchdog Timer Prescaler three, two, one, and null
The WDP3..0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is
enabled. The different prescaling values and their corresponding Timeout Periods are shown in
Table 11-2 on page
WDTON
1
1
1
1
0
1. WDTON fuse set to “0” means programmed, “1” means unprogrammed.
(1)
Watchdog timer configuration.
WDE
0
0
1
1
x
51.
51.
WDIE
0
1
0
1
x
Mode
Stopped
Interrupt mode
System Reset mode
Interrupt and System Reset
mode
System Reset mode
Action on timeout
None
Interrupt
Reset
Interrupt, then go to System Reset
mode
Reset
8042D–AVR–10/11