In the lab this week, I learned a lot about the serial communication of Arduino between other platforms and devices. The biggest challenge I encountered was the different languages between each output and input (ASCII decimal, ASCII character, binary…) 

Following the lab and videos step by step, I understood the p5.serial library and the call back functions. Though I still feel like there’s a lot of default setting or variables of the library that is a bit confusing, I had no trouble connecting Arduino to the browser and having the input data. 

[Read more…] about PComp Lab W6 : Serial Communication I

A Spooky Music Box

PComp project in collaboration with Gabe and Yiting

 

[Read more…] about PComp : Project 1

Analog Output

This week we’re mainly learning about analog output, and the three ways to write in Arduino IDE which can control different elements on the board.

analog.write();
tone();
servo.write();

Since Arduino board can only output a high or low voltage, so to create a seemingly changing voltage, we have to turn the pins on and off really fast (in milliseconds) to create a pseudo-analog output. [Read more…] about PComp Lab W3 – Analog Output

1. Digital Input and Output

starting week 2 lab by controlling digital input and output from a pushbutton. (figure 1.01, 1.02)

Question

• Why need a voltage divider? (or is it only a potentiometer that does not need it?)

 

 

 

 

 

 

2. Analog In with an Arduino

Adding a potentiometer to the breadboard, the input was read from an Analog pin, which was  what made it adjustable (not all-or-nothing like a digital pin) (figure 2.01, 2.02)

Then in the second circuit, 2 LED lights are controlled by 2 photocells. The input of the photocell determined the brightness of LED. (figure 2.03, 2.04)
However, 2 photocells (with same kind of fixed resistor) had 2 different ranges, so I had to map them separately. (figure 2.05)

Notes

• analogRead (pin) – value goes from 0 to 1023
  ➔ which means the resolution of Arduino’s reading is 1024 
• analogWrite (pin, value) – value goes from 0 to 255
• In the case of the potentiometer, who can give a full range from 0 to 1023, the read value should be divided by 4 in order to fit into the range of analogWrite
• When using other senses with a fixed resistor (voltage divider), it limits the range  and so the number divided should also be adjusted accordingly. To do so:
  ➔ 1. find the range – use Serial.print();
  ➔ 2. map the new range – let value = map (sensorValue, rangeMin, rangeMax, 0,255);

Question

• What does Serial.begin(9600) mean exactly, and when do we need to type this?

 

 

 

 

 

 

 

3. Sensor Change Detection

In this lab, we learned how to note the peak of input data, and printed them in the Serial Monitor. I used a pushbutton for digital input and a photocell for analog input. 

In the digital one, we practiced 2 states of the peak – one when the threshold is crossed, and one categorizing the length of pressing time. (figure 3.01, 3.02)

 

 

 

 

 

and in the analog one, I used a photocell, recording peaks of the values. (figure 3.03, 3.04)

 

 

 

 

 

 

Question

• I don’t quite understand the logic of the code in figure 3.04. When I hid the line ” if (sensorValue <= threshold) { ” the whole program still worked. I felt that the line was a bit redundant and lost my thread of the logic here.

 

1. connect a LED light

The first one I started with connecting a LED light to Arduino Nano 33 board.
I tried to connect the LED to 3 different pins of electricity supply on the board – 5V, 3.3V and V-in. (figure 1.1, 1.2,1.3)

Questions

•  Why doesn’t the LED light up when connecting to 5V?
• How many voltages are supplied by the V-in pin?

 

 

 

 

 

2. control a LED light with a pushbutton

adding a pushbutton in between the resistance and the LED light. (figure 2.1, 2.2)

 

 

 

 

 

3. control a LED light with 2 pushbuttons

2 pushbuttons parallel controlling the same LED light (figure 3.1, 3.2, 3.3)
also tried to draw a schematic of this circuit on Circuit Diagram (figure 3.4)

 

 

 

 

 

 

 

 

 

 

4. measure voltage with a multimeter

I used a multimeter to measure voltages of components of the same circuit as the previous one – both when the LED is on (figure 4.1, 4.2, 4.3) and off (figure 4.4, 4.5, 4.6)

Questions

• Why are the totals of voltages different when the switch is on and off?
  When the light was on the total voltage is around 5.77V, while when off it was 3.8V. 
• Why do the pushbuttons still have voltages when they are not pressed? (figure 

 

 

 

 

 

 

 

 

 

 

5. Using a potentiometer

Finally, I tried to control a LED light with a potentiometer (video demo) (figure 5.1)