Q:
Why do we need a ULN2803 in driving a relay?
belongs to collection: COMPUTER ARCHITECTURE - 8051 MICROCONTROLLER MCQ
COMPUTER ARCHITECTURE - 8051 MICROCONTROLLER MCQ
- 8051 series of micro controllers are made by which of the following companies?
- AT89C2051 has RAM of:
- 8051 series has how many 16 bit registers?
- When 8051 wakes up then 0x00 is loaded to which register?
- When the micro controller executes some arithmetic operations, then the flag bits of which register are affected?
- How is the status of the carry, auxiliary carry and parity flag affected if write instruction
- How are the bits of the register PSW affected if we select Bank2 of 8051?
- If we push data onto the stack then the stack pointer
- On power up, the 8051 uses which RAM locations for register R0- R7
- How many bytes of bit addressable memory is present in 8051 based micro controllers?
- DJNZ R0,label is how many bit instruction?
- JZ, JNZ, DJNZ, JC, JNC instructions monitor the bits of which register ?
- Calculate the jump code for again and here if code starts at 0000H
- When the call instruction is executed the top most element of stack comes out to be
- LCALL instruction takes
- Are PUSH and POP instructions are a type of CALL instructions?
- What is the time taken by one machine cycle if crystal frequency is 20MHz?
- Find the number of times the following loop will be executed
- What is the meaning of the instruction MOV A,05H ?
- Does the two instructions mean the same?
- To initialise any port as an output port what value is to be given to it?
- Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port?
- Which of the ports act as the 16 bit address lines for transferring data through it?
- Which of the following registers are not bit addressable?
- Which instruction is used to check the status of a single bit?
- Which addressing mode is used in pushing or popping any element on or from the stack?
- Which operator is the most important while assigning any instruction as register indirect instruction?
- What is the advantage of register indirect addressing mode?
- Which of the following comes under indexed addressing mode?
- Is this a valid statement ? SETB A
- When we add two numbers the destination address must always be
- DAA command adds 6 to the nibble if:
- If SUBB A,R4 is executed, then actually what operation is being applied?
- A valid division instruction always makes:
- In 8 bit signed number operations, OV flag is set to 1 if:
- In unsigned number addition, status of which bit is important?
- Which instructions have no affect on the flags of PSW?
- ANL instruction is used
- CJNE instruction makes
- XRL, ORL, ANL commands have
- What is the clock source for the timers?
- What is the frequency of the clock that is being used as the clock source for the timer?
- What is the function of the TMOD register?
- What is the maximum delay that can be generated with the crystal frequency of 22MHz?
- Auto reload mode is allowed in which mode of the timer?
- Find out the roll over value for the timer in Mode 0, Mode 1 and Mode 2?
- What steps are followed when we need to turn on any timer?
- If Timer 0 is to be used as a counter, then at what particular pin clock pulse need to be applied?
- In the instruction “MOV TH1,#-3”, what is the value that is being loaded in the TH1 register ?
- TF1, TR1, TF0, TR0 bits are of which register?
- Which devices are specifically being used for converting serial to parallel and from parallel to serial respectively?
- What is the difference between UART and USART communication?
- Which of the following best describes the use of framing in asynchronous means of communication?
- Which of the following signal control the flow of data?
- Which of the following is the logic level understood by the micro-controller/micro-processor?
- What is null modem connection?
- Which of the following best states the reason that why baud rate is mentioned in serial communication?
- With what frequency UART operates( where f denoted the crystal frequency )?
- What is the function of SCON register?
- What should be done if we want to double the baud rate?
- When any interrupt is enabled, then where does the pointer moves immediately after this interrupt has occurred?
- What are the contents of the IE register, when the interrupt of the memory location 0x00 is caused?
- After RETI instruction is executed then the pointer will move to which location in the program?
- Which pin of the external hardware is said to exhibit INT0 interrupt?
- Which bit of the IE register is used to enable TxD/RxD interrupt?
- Which of the following combination is the best to enable the external hardware interrupt 0 of the IE register (assuming initially all bits of the IE register are zero)?
- Why normally LJMP instructions are the topmost lines of the ISR?
- Which register is used to make the pulse a level or a edge triggered pulse?
- What is the disadvantage of a level triggered pulse?
- What is the correct order of priority that is set after a controller gets reset?
- How many rows and columns are present in a 16*2 alphanumeric LCD?
- How many data lines are there in a 16*2 alphanumeric LCD?
- Which pin of the LCD is used for adjusting its contrast?
- For writing commands on an LCD, RS bit is
- Which command of an LCD is used to shift the entire display to the right?
- Which command is used to select the 2 lines and 5*7 matrix of an LCD?
- What changes are to be made to send data to an LCD?
- For reading operation from an LCD what changes in the software are introduced?
- Which instruction is used to select the first row first column of an LCD?
- The RS pin is an input or output for a controller?
- Which of the following steps detects the key in a 4*4 keyboard matrix about the key that is being pressed?
- What is described by this command: CJNE A,#00001111b, ROW1
- To detect that in which column, the key is placed?
- In reading the columns of a matrix, if no key is pressed we should get all in binary notation
- If we need to operate a key of a keyboard in an interrupt mode, then it will generate what kind of interrupt?
- To identify that which key is being pressed, we need to:
- Key press detection and Key identification are:
- Why two pins for ground are available in ADC0804?
- When is the function of the WR pin?
- State which of the following statements are false?
- While programming the ADC0804 IC what steps are followed?
- Step size is selected by which two bits?
- What is the difference between ADC0804 and MAX1112?
- Which of the following statements are true about DAC0808 ?
- 8 input DAC has
- INTR, WR signal are an input/output signal pin ?
- What is the function of the SCLK pin in MAX1112 ?
- A thermistor is a:
- What is the difference between LM 34 and LM 35 sensors?
- Transducers produce output voltage in the form of?
- What is signal conditioning?
- What steps have to be followed for interfacing a sensor to a micro controller 8051?
- LM35 has how many pins?
- Why Vref is set of ADC0848 to 2.56 V if analog input is connected to the LM35?
- What is the function of 8255 chip?
- Which pins of a micro controller are directly connected with 8255?
- Find the control word for PA= out, PB= in, PCL=out, PCH=out (Mode0)?
- Which pins are used to select the ports and the control register?
- What is the value of the control register when RESET button is set to zero?
- Why MOVX instruction is being used to access the ports of the 8255?
- What is correct about the BSR mode from below?
- How many pins of the 8255 can be used as the I/O ports?
- DS12887 is a
- What is the RAM space that a DS12887 have?
- How many bytes of the ROM are there for the general purpose applications?
- Which bits of the Register A are used for turning on the oscillator?
- Which out of the following is correct about the SQW pin?
- What is correct about the UIP pin of the register A?
- What is the byte address where time, calendar, alarm address locations etc are kept?
- Are the RAM locations of the DS12887 non volatile?
- Name the read only registers are present in the DS12887?
- What is the supply that a DS12887 consumes even when the power is switched off?
- What is the principle on which electromagnetic relays operate?
- What are DPDT relays?
- Why do we need a ULN2803 in driving a relay?
- Why are solid relays advantageous over electromagnetic relays?
- What are optoisolators?
- How can we control the speed of a stepper motor?
- Which of the following can be a unit for torque?
- The RPM rating given for the DC motor is for?
- PWM allows the control of a DC motor with the same phase, but with different amplitude phases?
- How can the direction of the DC motor be changed?
- Everything compatible with PHP on client side is also compatible with
Computer
PIC (Programmable Integrated Circuits)
(b).for increasing the current limit in the relays
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