Extract Chip ATmega169P Code after decode atmel avr processor atmega169p flash memory and restore embedded heximal from microcontroller atmega169p eeprom memory;
The calibrated internal RC Oscillator provides a fixed 8.0 MHz clock. The frequency is nominal value at 3V and 25°C. If 8 MHz frequency exceeds the specification of the device (depends on VCC), the CKDIV8 Fuse must be programmed in order to divide the internal frequency by 8 during start-up.
The device is shipped with the CKDIV8 Fuse programmed. See “System Clock Prescaler” on page 29. for more details. This clock may be selected as the system clock by programming the CKSEL Fuses as shown in Table 8. If selected, it will operate with no external components when copying atmega169pv ic mcu flash memory heximal file. During reset, hardware loads the calibration byte into the OSCCAL Register and thereby automatically calibrates the RC Oscillator.
At 3V and 25°C, this calibration gives a frequency within ± 10% of the nominal frequency. Using calibration methods as described in application notes available at www.atmel.com/avr it is possible to achieve ± 2% accuracy at any given VCC and Temperature. When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the Watchdog Timer and for the Reset Time-out.
For more information on the pre-programmed calibration value, see the section “Calibration Byte” on page 269. When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in Table 9. Selecting internal RC Oscillator allows the XTAL1/TOSC1 and XTAL2/TOSC2 pins to be used as timer oscillator pins.
Writing the calibration byte to this address will trim the internal Oscillator to remove process variations from the Oscillator frequency. This is done automatically during Chip Reset. When OSCCAL is zero after readout ic mcu controller atmega1284 source code of flash memory, the lowest available frequency is chosen. Writing nonzero values to this register will increase the frequency of the internal Oscillator.
Writing 0x7F to the register gives the highest available frequency. The calibrated Oscillator is used to time EEPROM and Flash access. If EEPROM or Flash is written, do not calibrate to more than 10% above the nominal frequency. Otherwise, the EEPROM or Flash write may fail. Note that the Oscillator is intended for calibration to 8.0 MHz. Tuning to other values is not guaranteed, as indicated in Table 10.
When applying an external clock, it is required to avoid sudden changes in the applied clock frequency to ensure stable operation of the MCU. A variation in frequency of more than 2% from one clock cycle to the next can lead to unpredictable behavior. It is required to ensure that the MCU is kept in Reset during such changes in the clock frequency.
Note that the System Clock Prescaler can be used to implement run-time changes of the internal clock frequency while still ensuring stable operation. Refer to “System Clock Prescaler” on page 29 for details. When the CKOUT Fuse is programmed, the system Clock will be output on CLKO. This mode is suitable when chip clock is used to drive other circuits on the system.
The clock will be output also during reset and the normal operation of I/O pin will be overridden when the fuse is programmed. Any clock source, including internal RC Oscillator, can be selected when CLKO serves as clock output. If the System Clock Prescaler is used, it is the divided system clock that is output when the CKOUT Fuse is programmed.
