Extract IC ATMEGA8V Binary from its memory and by using focus ion beam to disable the security fuse bit, turn the status of MCU from locked to unlocked one through MCU breaking technique;
On the IC ATMEGA8V devices, the DRT runs any time the device is powered up. The DRT operates on an internal oscillator. The processor is kept in Reset as long as the DRT is active.
The DRT delay allows VDD to rise above VDD min. and for the oscillator to stabilize. The on-chip DRT keeps the devices in a Reset condition for approximately 18 ms after MCLR has reached a logic high (VIH MCLR) level if mcu atmega261pv code extraction.
Programming GP3/MCLR/VPP as MCLR and using an external RC network connected to the MCLR input is not required in most cases. This allows savings in cost-sensitive and/or space restricted applications, as well as allowing the use of the GP3/MCLR/VPP pin as a general purpose input.
The Device Reset Time delays will vary from chip-to- chip due to VDD, temperature and process variation. See AC parameters for details. Reset sources are POR, MCLR, WDT time-out and wake-up on pin change.
See Section 9.9.2 “Wake-up from Sleep”, Notes 1, 2 and 3.
The WDT has a nominal time-out period of 18 ms, (with no prescaler). If a longer time-out period is desired, a prescaler with a division ratio of up to 1:128 can be assigned to the WDT (under software control) by writing to the OPTION register.
Thus, a time-out period of a nominal 2.3 seconds can be realized. These periods vary with temperature, VDD and part-to-part process variations (see DC specs).
Under worst-case conditions (VDD = Min., Temperature = Max., max. WDT prescaler), it may take several seconds before a WDT time-out occurs before chip atmega461pa firmware reading.
9.6.2 WDT PROGRAMMING CONSIDERATIONS
The CLRWDT instruction clears the WDT and the postscaler, if assigned to the WDT, and prevents it from timing out and generating a device Reset. The SLEEP instruction resets the WDT and the postscaler, if assigned to the WDT. This gives the maximum Sleep time before a WDT wake-up Reset.
