Photo of arduino with force sensors connected to laptop and a speaker

Week 3 Lab: Tone output and servo motor control

Tone outputs

Wiring sensors and speakers

Arduino with force sensors connected to laptop and a speaker

First, I connected one potentiometer and one force sensing resistor to the circuit.

Photo of fingers pressing force sensors that is connected to laptop and a speaker via Arduino

The speaker's loudness changes slightly when pressing the sensor.

After connecting the Arduino to a power source, I could hear the speaker's sound changing.

Arduino's serial monitors giving continuous outputs between 0~250, following the force sensor's pressure

Also, I could see the analog sensor's input values ranging from 0 to 250 from the serial monitor.

Changing frequency

screen capture of arduino code using the map function to convert variable ranges

map() converting the input values to different ranges, from 0~250 to 100~1000

After changing the sound, I wanted to change the frequency, or the tone of the sound. I used the map function to map the analog input values from 0~250 to 100~1000.

Arduino's serial monitor giving a value between 100 and 1000

Unfortunately, after uploading the code, the speaker won't play any sounds. However, the sensor and code seemed to work well because I was getting good values between 100 to 1000 in the serial monitor.

Photo of a speaker that says 4 ohms and 3 watts in the back

Speaker description in the back, indicating 4 ohms and 3 watts

I then discovered my speaker's impedance was 4 ohm, which was different from the 8 ohm speakers in the lab example. After searching, I discovered that 4 ohm speakers required more currents according to Ohm's law. Or, I could connect two 4 ohm speakers in serial.

Unfortunately I had only one speaker which was 4 ohm, so I couldn't solve this issue. However, I learned that I can manipulate different analog inputs and convert them into analog outputs.

Servo motor control

Arduino connected with force sensors and servo motor

Photo of arduino serial monitor giving values around 500 from the force sensor input

Pressing the sensor firmly - giving a maximum value around 500 in the serial monitor

First, I wired the sensors and servo motor. I checked the range of the force sensor - it was roughly from 0 to 500.

Arduino serial monitor giving a mapped input of 0 to 179

I also mapped the input from 0~500 to 0~179, in order to match the controls of servo motor.

Arduino code controlling the servo motor

Next, I modified and uploaded the servo motor code to arduino. However, the motor didn't work. I double-checked the wiring, made sure that the connections to the servo motor was firm, tried changing the servo motor to another one, but I still could not figure out the problem.