Lab 5: IR Lab

In this portion of the lab, we will be looking at control versus communication (communication is what we worked with in the prior lab). The difference between the two is that with control, there is less information sent to devices, with each bit of information carrying a particular function. With communication, there is a stronger focus on sending the information from one device to another.

We will be dealing with two different communication/interpretation processes. During the first process, the raw digital signal is reformatted so that the receiving device will understand it. Other formatting is also done so that the receiving device will be the only one understanding it (a TV will be controlled by only a TV remote). The second process is known as modulation, where the signal is able to put the signal into a specific frequency band. This will prevent signals from interfering (which could cause constructive or destructive interference) and will also filter out background noise.

We first set up the Arduino IR Remote Library and created two circuits: a receiver circuit and a transmit circuit.

The receiver circuit is shown below:


The transmit circuit is shown below:



Our video shows the overall performance of this setup. The code is attached here.

Next, we sent the same IR code to trigger an action in the previous step. Since we are working with Sony codes, we'll use Sony-specific protocol. We set up both the receiver and transmit circuits so that the first Arduino can translate the IR signal into a command, and turn the LED on and off each second.

Here is the video.

Receiver and transmitter code are both attached here.

Lab 5: Bluetooth Lab

Part 1

Many of us have utilized several bluetooth-enabled technologies, as the advantages of this wireless communication have caused it to become a widely used tool. Radio frequency (RF) communication operates at a frequency of 2.4 GHz and allows for data transmission through a "sending" and "listening" module. Bluetooth devices that are communicating are "paired" together so that only one particular listening module receives information from a specific sending module.

With regards to this class, we will receive two modules that are pre-programmed to communicate only with each other. Then we will connect the serial input and output of the Arduino to the serial input and output of the bluetooth module. We will use SofwareSerial to set up the software serial connection.

The purpose of this lab is to set up a bluetooth transmitter and receiver and create a wireless button to buzzer connection.

In the first portion, we set up the bluetooth transmitter so that the Serial Monitor would print "H" when the button is pressed and print "L" when the button is released. Rather than work with one Arduino, the signal will be wirelessly delivered. Since we didn't want the transmitter to be sending a continuous stream of letters, like what usually happens, we made use of an if statement so that the "H" or "L" would only be displayed once. Below is an image of our circuit.



For this part, our code is attached here.

Then we had to create a bluetooth receiver. After connecting the second bluetooth module to the other Arduino Board, setting up the LED, and writing a program for the LED to turn on if the Serial Monitor had an "H" (and off when "L"), we obtained our results. Below is an image of our circuit.



The code is attached here.

Finally, below is a video for this portion of the lab.

 Next, we wrote a program so that our transmitter could print different numbers to the serial port once every second. For example, the number would increment every second. Then, the integer value would be transmitted onto the LCD screen.

The code is attached here. Here is the video for this part of the lab.

Part 2

In this portion of the lab, we will acquire a continuously varying signal from a sensor and then send this signal wirelessly. We will use an inertial measurement unit (IMU) as our sensor, which can measure acceleration, rotation rate, and magnetic field all around three axes. It also has an on-board micro-controller that can perform calculations and provides data combining all of the detailed measurements.

We started off by installing two libraries developed by Adafruit, created the apparatus, and then used the program by Dr. Bogen. Then we wrote the program to monitor the IMU's orientation about a specific axis and map the orientation angle into a tune on an Arduino device that is located away from this apparatus.

Some issues we faced: the provided code gave instructions on calibrating the IMU but we were unable to find a rotation that calibrated the IMU. Soon enough, we figured out that if the IMU and the circuit board was rotated into different positions and then held there, it would eventually calibrate.

In order for the tune to play, we had to associate each orientation angle with a different frequency that would then result in a unique sound. First we converted the angle values into tone frequency values. Then we broadcasted these values using the bluetooth module (and this was through our transmitter-Arduino). Next, we had the second receiver-Arduino collect the data from the transmitter-Arduino. Then, the tones were played.

Our new circuit was a little different:




Our video is shown below.

Finally, the code is attached here.

Lab 4: Nonvolatile Storage

The purpose of this lab was to store data in nonvolatile storage, construct a data logger from nonvolatile data, and work with RC servos.

Essentially, memory on the Arduino is erased when the Arduino shuts off however, by storing the data into Electrically, Erasable, Programmable, Read-Only Memory (EEPROM), we can go around this to add greater utility to our Arduino. By using the Write() and Read() functions, we were able to write the data to the EEPROM and then read it after the Arduino shut down.

In our program, when we type a W into the Serial Monitor, the program began writing the data into the EEPROM and when we type a an R, we have the program read and display the data into the Serial Monitor. The code is attached here.

The following is what we obtained in our Serial Monitor. In the first line, the Serial Monitor displays "saving 0 at location 0." This means that the Serial Monitor read the value of 0 and wrote it onto the EEPROM.



Some issues we had in this portion of the lab: we accidentally created an infinite loop with i equal to 0 by typing "for(int i = 0; i < 6; i = i++)" but to fix this, we changed the loop to "for(int i = 0; i < 6; i = i+1)."
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Part 2

In the second portion of this lab, we built a data logger for light intensity measurements by the Arduino. Our circuit resembled a variable resistance sensor with a photo-resistor, a voltage divider circuit, and the analogRead() function. This was similar to the work that we did in Lab 2. Once again, we used a 5.1 kOhm resistor because it was closest to the resistance of the photo-resistor provided.

Of course, we had to remember that not all pins work with the analog output and input, which was something we momentarily forgot. Luckily, we didn't take too much time to realize this was one of the issues we ran into.

Our circuit looked like this:



The code for the light sensor is found here.

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Next, we had to write code so that the data logging device we make takes a measurement from the sensor at a regular rate (15 seconds for a duration of 3 minutes) and stores all of these data points into the EEPROM. The code for this portion is found here. (The code from the previous portion was slightly edited to achieve this.)

Next, we had to have this information displayed in the Serial Monitor. Here is the code. The image below shows the readings from the Serial Monitor. We can see that for 3 minutes, or 180 seconds, these readings were taken and recorded.



One of the issues we faced in this portion of the lab was receiving different outputs from EEPROM.read() versus analogRead(). We discovered that analogRead() pins produce an output between 0 and 1023, which is why they had to be scaled down when we were writing them through the EEPROM.write() function.

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Then, we wrote a front end which would allow us to select if we wanted to start the data-logging process or whether we wanted to read the already-logged data. The serial input from the Serial Monitor was used to choose between data-logging and data-reading. The code is attached here.

The image below shows the Serial Monitor when w is pressed.



and




The image below shows the Serial Monitor display when r is pressed.



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In the third portion of this lab, we built a rotational positioning device. Our circuit was to look like this:



The actual circuit looked like this:



Next, we started to control the servo position, or the rotation of the motor with the Arduino. We controlled the servo by sending pulses to the Arduino every 20 ms or so, with pulses that were approximately 1-2 ms in width. The code can be found here.

In the next portion, we had to write a program to have the motor move at a specified angular position, which was to be inputted into the Serial Monitor. We had a significant amount of trouble in this portion of the lab. One important component of this code was a while loop, through which we could enter integers into the Serial Monitor and the output would be the ASCII equivalent. The second component was when we had to close the if loop for serial.available(). Without these parts, entering inputs into the Serial Monitor would result in the motor taking a single-step towards the direction of the inputted location.

We have a video that displays what our code was before we corrected this mistakes:



And one after we corrected for this mistake:


We believed it would be worth while to really understand this mistake as our final project would require similar code. The code is attached here.

Next, we made the servo motor rotate back and forth between two different positions. The code is attached here and the video is below.



Next, we controlled for the servo speed for the back and forth motion of the prior task. The code is attached here and the video is below.



Then, we created a program that would allow us to set the servo speed from the Serial Monitor. The code is attached here and the video is below.



Finally, we had to build a rotational positioning device. Meaning, after mounting a cardboard disk on a servo motor, we want to make the hole positioned over the sensor on command. Essentially, the motor would take information based on the light in the area in order to figure out where the hole is and where to position the servo motor.

Our circuit looked like this:


Finally, our code is attached here and the video is attached below.