8051 Micro-controller Multiple Choice Questions on “Interfacing with RTC”.
1. DS12887 is a ____________
a) Timer IC
b) Serial communication IC
c) RTC IC
d) Motor
Answer: c
Clarification: DS12887 is a real time clock that is widely used to provide accurate time and date for many applications.
2. DS12887 has _____ amount of RAM.
a) 14 bytes
b) 114 bytes
c) 128 bytes
d) 64 bytes
Answer: c
Clarification: DS12887 has 128 bytes of non-volatile RAM.
3. DS12887 has _____ amount of RAM for general purpose applications.
a) 9 bytes
b) 114 bytes
c) 128 bytes
d) 14 bytes
Answer: b
Clarification: DS12887 has 128 bytes of non-volatile RAM. Out of 128 bytes, 14 bytes of RAM for clock/calendar and control registers, and another 114 bytes of RAM for general purpose data storage.
4. In DS12887, which bits of the Register A are used to turn on the oscillator?
a) D4
b) D5
c) D6
d) All of the mentioned
Answer: d
Clarification: In DS12887, D4-D6 bits of register A are used to turn on the oscillator. A specific value of 010 of D4-D6 is desirable for turning on the oscillator.
5. In DS12887, which out of the following is correct about the SQW pin?
a) it is an output pin
b) it can provide up to 15 different square waves
c) the frequency of the square wave is set by the register A
d) all of the mentioned are correct
Answer: d
Clarification: In DS12887, SQW pin stands for SQuare Wave. It is an output pin that can provide us with 15 different square waves. The frequency of the square wave is selected by programming register A.
6. In DS12887, what is correct about the UIP bit of the register A?
a) it is a read only bit
b) it is used to know about the result
c) it is used to select the DS12887 datasheet
d) all of the mentioned
Answer: a
Clarification: In DS12887, UIP bit of register A stands for Update In Progress. The update-in-progress (UIP) bit is a status flag i.e. read-only bit.
7. In DS12887, what is the range of RAM addresses which are used to store the values of time, calendar and alarm data?
a) 00-7FH
b) 00-09H
c) 0EH-7FH
d) 0A-0DH
Answer: b
Clarification: In DS12887, the first ten locations i.e. 00-09H are used to store the values of time, calendar and alarm data.
8. Is DS12887 has non-volatile RAM?
a) Yes
b) No
c) Can’t be determined
d) None of the mentioned
Answer: a
Clarification: Yes, DS12887 has non-volatile RAM.
9. Name the read only registers are present in the DS12887?
a) register A, register B
b) register B, register C
c) register C, register D
d) register D, register A
Answer: c
Clarification: Register C and D are the read only registers in the DS12887 found at memory locations 0C-0DH.
10. In DS12887, when the external source is turned-off, how does DS12887 get power to retain its data?
a) Internal Lithium Battery
b) Internal Lead Battery
c) Additional external Alkaline Battery
d) Additional external Lithium Battery
Answer: a
Clarification: When Vcc falls below 3V or external voltage source is switched-off, internal lithium battery provides power to DS12887. And this will prevent loss of data.