REVIEW QUESTIONS

REVIEW QUESTIONS

1. The ADC module inside the PIC microcontroller used to convert analogue signal from

temperature sensor LM35. If the Vref (+) of the ADC module is taken from an external

source. Sketch a simple circuit to interface temperature sensor LM35 with PIC

microcontroller.

2. A PIC18 is connected to the 10 MHz crystal oscillator. Calculate the conversion time

for the following options: a. Fosc/32

b. Fosc/16

3. A temperature sensor LM35 uses to detect an environment temperature. The output from the sensor is 10mV/ ºC. The sensor is connected to the PIC18F4550 as shown in

Figure 6.11. The 10-bit ADC module in the PIC18F4550 is configured to use VREF(+) =

Vdd, VREF(-)= Vss. Assume Vdd = 5V and Vss = 0V. Calculate the digital output, if the

environment temperature is 32 ºC

Figure 6.11

4. An ADC module inside a PIC microcontroller is used to convert analogue signals from

Maxsonar ultrasonic sensors. The specification analogue output from the sensor is

illustrated in Figure 6.12. Calculate Digital Output, if sensor detect 10 cm in front of sensor

if the ADC module is used with following setting:

Resolution = 10-bit

Vref(+) = 3V Vref(-)= 0V

Figure 6.12

The LM35 series sensors are precision integrated temperature sensors whose output is 10mV

for each degree of centigrade temperature. Demonstrate why we set the Vref of the PIC to

2.56V if the analog input is connected to the LM35?