Arduino Questions and Answers – ADXL335 Accelerometer Sensor


This set of Arduino online quiz focuses on “ADXL335 Accelerometer Sensor”.

1. What is the use of the ADXL-335 sensor?
a) To measure acceleration
b) To measure heat
c) To measure temperature
d) To measure GPS Location
View Answer

Answer: a
Explanation: The ADXL-335 is an accelerometer which can calculate the instantaneous acceleration. It can be used for many applications, most importantly in phones, since it can be also used for calculating the roll or tilt.

2. How many pins are present in the ADXL-335?
a) 1
b) 4
c) 2
d) 5
View Answer

Answer: d
Explanation: The ADXL-335 Accelerometer has 5 pins which correspond to Vcc for powering the device, GND for completing the circuit, and X,Y,Z pins which give the sensor’s output to be calculated with the help of a microcontroller.

3. What mode should the 3 axis pins of the ADXL-335 be read in, in an Arduino in order to obtain meaningful values?
a) Analog
b) Digital
c) PCM
d) TDM
View Answer

Answer: a
Explanation: The axis pins of the ADXL-335 Accelerometer give output in the form of analog signals. These should then be read from the Arduino with the help of the “analogRead()” method so as to obtain the full voltage value that they are putting out.
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4. What will happen if we supply a voltage of 25V to the Vcc of the ADXL-335 sensor?
a) Damage is caused
b) Sensor will work fine
c) Sensor will not respond for the time the voltage is applied
d) Sensor will function normally
View Answer

Answer: a
Explanation: The ADXL-335 Accelerometer modules are mostly built to work on a voltage range of approximately 3.3V to 5V. Any voltage lower than that and the sensor will not be able to power on, but however any voltage significantly above that and the sensor may suffer permanent damage.

5. Which of the formulae give us the value of acceleration for the x-axis in the ADXL-335?
a) Axout = (((Value * Vref) / 1024) – 1.65) / 0.330
b) Axout = (((Value * Vref) / 1024) – 1.65) / 2000
c) Axout = (((Value * Vref) / 1024) – 1.65) / 330
d) Axout = (((Value * Vref) / 1024) – 1.65) / 0.12
View Answer

Answer: a
Explanation: (((Value * Vref) / 1024) – 1.65) / 0.330 gives the correct value of acceleration along any axis of the accelerometer module. However, in order to make the equation work, we would need to plug in the values of the X-axis, Y-axis, and Z-axis separately in 3 different variables to obtain the value of acceleration along each individual axis.

6. Which of the formulae give us the angle of inclination in the ADXL-335?
a) theta=atan(X_Value/sqrt((Y_Value*Y_Value)+(Z_Value*Z_Value)))
b) theta=atan(X_Value/sqrt((Y_Value*Y_Value)*(Z_Value*Z_Value)))
c) theta=atan(X_Value/sqrt((Y_Value)+(Z_Value*Z_Value)))
d) theta=atan(X_Value/sqrt((Y_Value*Y_Value)+(Z_Value)))
View Answer

Answer: a
Explanation: atan(X_Value/sqrt((Y_Value*Y_Value)+(Z_Value*Z_Value))) gives the correct value of the angle of inclination of the accelerometer module. Here all the three values read from the 3 data pins of the ADXL-335 module are to be replaced in the equation at the same time in order for this to work.

7. Can you measure the acceleration of a train, if the train is moving at a constant velocity and the sensor is located on the train?
a) Yes
b) No
View Answer

Answer: a
Explanation: Yes, you can measure the acceleration of the train but in this case the acceleration value of the train is going to be 0 since acceleration is the rate of change of velocity with time and in this case since the velocity of the train is constant with respect to time, then the acceleration measured by the sensor should be 0.

8. What kind of sensor is the ADXL-335 Accelerometer Module?
a) Passive
b) Active
c) Radio
d) Pressure based
View Answer

Answer: b
Explanation: The ADXL-335 sensor is an active sensor since it requires an active DC voltage source to function properly. On the contrary, an LDR can be said to be a sort of a passive sensor since it does not require the input of current from an external source for its working.

9. The ADXL-335 Accelerometer sensor module uses capacitive technology to detect changes. The Equation governing that function is given by C=f(A/d). What is the meaning of ‘A’ in the equation?
a) Area
b) Air
c) Antenna
d) Acceleration
View Answer

Answer: a
Explanation: The ADXL-335 Accelerometer sensor uses capacitive technology to carry out its functions. I the equation C=f(A/d), ‘A’ stands for the area of the plate, and the ‘d’ stands for the distance of separation between the two plates.

10. What is the drawback of the code given below?

  1. int val, Vref=5;
  2. void setup() {
  3.     Serial.begin(9600);
  4. }
  5. void loop() {
  6.     val= (((analogRead(A3) * Vref) / 1024) – 1.65) / 0.330;
  7. }

a) Wrong pin number
b) Wrong equation
c) Wrong target datatype
d) Incorrect parenthesis
View Answer

Answer: c
Explanation: The code gives the value of acceleration along one of the axes of the accelerometer. The equation is alright but the target datatype should be a double, and not an int, since then it would be very inaccurate.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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