The PIC 12F629 and 12F675 devices have an internal 4Mhz oscillator that enables the devices to be used without an external crystal or RC network. This frees up one or two pins for I/O use and allows the device to be built into minimum component count designs.
What is the frequency of the oscillator in the Pic?
The frequency of the internal oscillator in the PIC varies with both changes in temperature and supply voltage. As the supply voltage increases the frequency decreases slightly. When switch S1 is open the 5 volt supply to the PIC is dropped across the two diodes to about 3.4 volts.
Why do I need to calibrate my oscillator?
This frees up one or two pins for I/O use and allows the device to be built into minimum component count designs. The internal oscillator needs to be calibrated and this is achieved by reading a factory programmed calibration setting and writing it into the OSCCAL register during initialisation of the device by the application software.
How to calibrate the osccal value in eeeeprom?
EEPROM address 0x00 contains 0x34 and address 0x01 contains 0xNN where NN is the new calibration setting. then the code ran successfully (finished with ‘done’ LED on) and calibrated the OSCCAL value correctly. Use the 0xNN value in address 0x01 for the calibration memory.
