ADC, DAC, and Sensor Interfacing - Unit 13 - Review Questions & Answers from 8051 Microcontrollers & Embedded Systems by Mazidi

 SECTION 13.1: PARALLEL AND SERIAL ADC

1. In the ADC0804, the INTR signal is an ______ (input, output). 

2. In the ADC0804, to begin conversion, send a(n) pulse to pin_______.

3. Which pin of the ADC0804 indicates end-of-conversion?

4. Both the ADC0804 and ADCOSOS/0809 are ________ -bit converters.

5. Indicate the direction (out, in) for each of the following pins of the ADCOSOS/0809. 

    (a) A, B, C     (b) SC     (c) EOC

6. In the ADC0848, the INTR signal is an _______ (input, output).

7. In the ADC0848, to begin conversion, send a(n) ______ pulse to ________

8. Which pin of the ADC0848 indicates end-of-conversion? 

9. The ADC0848 is a(an) _______ -bit converter.

10. True or false. While the ADC0848 has 8 pins for Dout, the MAX1112 has only one Dout pin. 

11. Indicate the number of analog input channels for each of the following ADC chips.

    (a) ADC0804     (b) ADC0848     (c) MAX1112 

12. Explain how to select analog input channel for the MAXl 112. 

Answers: 

1. Output 

2. L-to-H, WR

3. INTR 

4. 8 

5. (a) all in     (b) in     (c) out

6. Output 

7. L-to-H, WR

8. INTR 

9. 8 

10. True

11. (a) 1     (b) 8     (c) 8

12. We send the control byte to the DIN pin one bit at a time. 

SECTION 13.2: DAC INTERFACING

1. In a DAC, input is ___________ (digital, analog) and output is _______ (digital, analog). 

2. In an ADC, input is ___________ (digital, analog) and output is ________ (digital, analog).

3. DAC0808 is a(an) _______ -bit D-to-A converter. 

4. (a) The output of DAC0808 is in ___________ (current, voltage).

    (b) True or false. The output of DAC0808 is ideal to drive a motor. 

Answers: 

1. Digital, analog. 

2. In ADC the input is analog, the output is digital. 

3. 8 

4. (a) current (b) true 

SECTION 13.3: SENSOR INTERFACING AND SIGNAL CONDITIONING

1. True or false. The transducer must be connected to signal conditioning circuitry before it is sent to the ADC.

2. The LM35 provides m V for each degree of (Fahrenheit, Celsius) temperature. 

3. The LM34 provides m V for each degree of (Fahrenheit, Celsius) temperature.

4. Why do we set the 

V,ef of ADC0848 to 2.56 V if the analog input is connected to the LM35? 

5. In Question 4, what is the temperature if the ADC output is 0011 1001? 

Answers: 

1. True 

2. 10, Celsius.

3. 10, Fahrenheit. 

4. Since ADC0848 is an 8-bit ADC, it gives us 256 steps, and 2.56 V /256 = 10 mV. LM35 produces 10 m V for each degree of temperature which matches the ADC's step size. 

5. 00111001 = 57, which indicates it is 57 degrees.