Real Time Clock

Question 1

Main component of RTC

Answer 1

Oscillator

Question 2

Which oscillator is used and why?

Answer 2

Quartz crystal oscillator with frequency 3.2768 kHz. easy to obtain 1 Hz using frequency divider, 2^15 is 32768. Above audible range

Question 3

Components of RTC

Answer 3

Oscillator - frequency divider and control - square wave output - time and calendar register - alarms and control registers - I2C ; power supply, temperature sensor

Question 4

How is error tuned in RTC

Answer 4

f’ = (f + ppm)/ 1 million

Question 5

Role of temperature sensor

Answer 5

To get data related to change in frequency with respect to change in temperature

Question 6

Methods of changing frequency

Answer 6

Comparing with estimated frequency - changing that particular count or distributing the change between a set of counts; using watchdog timer

Question 7

How is watchdog timer used in RTC?

Answer 7

Watchdog time goes of from a fixed time and if the program does not stop it on a particular time it will reboot or take some triggered action. This checks the RTC for any malfunctioning

Question 8

How is frequency changed in RTC?

Answer 8

Using load capacitor