Assignment Brief:

1. As a group probe an input device's analog levels and analyze its digital signals.
2. Measure a parameter using a sensor. Integrate the sensor with a custom-designed microcontroller board and read its data.

Input Devices: Previously

Input devices are hardware components that allow users to enter data, commands, or signals into a computer or other electronic systems. They convert physical actions or external data into digital signals that the system can process.

Personally, I had used an ultra sonic sensor in on eof the mini projects I did a year age, which was the first time I understood basics of Input and output devices. So, the first input device I used was an ultra sonic sensor. I also used a servo motor as an output. The project was a simple game, inspired by the mobile application game of Talking Tom, I built a frowning Cat, who uses a knife whenever a user comes near.

Input Devices: Week 09

Later, to understand the existing Input devices, I referred to the internet and chat gpt to leanr about the existing Input devices and their range of study. To learn more about sensors you can visit Autodesk Instructables to find DIY projects related to these sensors.

In this week, as I learnt about different sensors, I analysed the sensor that I could incorporate in my Final Project. After talking to my mentors Pranav Gawde and Jesal Mehta, I finalized the sensors that could help my final project idea. As per this and as an explorative lense I chose the sensors I would use for this week. That is:

1. Touch sensor
2. Accelorometer MP6040 6-axis (This I tried for explorative purpose.)

You can buy the Accelerometer and Ultrasonic sensor from Robu.in, Bolow is the link attatched to buy, MPU-6050 3-Axis Accelerometer and Gyro Sensor, the price for which is Rs. 189 as per Indian currency and an Touch sensor, the price for which is Rs. 24 as per Indian currency. As the products arrived, I understood the pinouts of both the sensors.

Touch Sensor

For better understanding of how I went through the project, lets go step by step. First Lets understand the Touch sensor. A touch sensor detects physical contact (like a finger touch) and converts it into an electrical signal. It is commonly used in touchscreens, buttons, and interactive devices.

Touch Sensor Type	Working Principle	Applications	Advantages	Limitations
Capacitive	Measures changes in capacitance when a conductive object (finger) disrupts the electric field.	Smartphones, touchpads, control panels, tablets.	High sensitivity, multi-touch support, durable, scratch-resistant.	Doesn't work with non-conductive objects (gloves, stylus), affected by water/humidity, higher cost.
Resistive	Two conductive layers separated by a gap touch when pressed, completing a circuit.	ATMs, industrial touchscreens, older touch devices.	Works with any object (stylus, gloves), lower cost, durable in harsh conditions.	Less sensitive, no multi-touch support, prone to wear and tear.
Infrared	Uses IR LEDs and photodetectors; touch blocks the infrared beam.	Interactive kiosks, public touch displays, medical devices.	Works with any material, long lifespan, high durability.	Can be affected by dirt, dust, and strong ambient light.
Piezoelectric	Generates a small electric charge when pressure is applied.	Industrial applications, harsh environments, touch-sensitive musical instruments.	High durability, works in extreme conditions, no need for conductive materials.	Expensive, requires strong force to activate.
Optical	Uses cameras or light sensors to detect touch disruptions.	Large interactive displays, multi-touch tables, high-end kiosks.	High accuracy, supports multi-touch, durable.	Expensive, bulky, requires calibration.

I used the a capacitive touch sensorwhich detects touch by measuring changes in electrical capacitance. It consists of a conductive surface and an electric field. When a conductive object (like a human finger) comes close, it disrupts the field, changing the capacitance. Surface Capacitive - Uses a thin conductive layer where a small current flows upon touch.

Design and Fabrication: refer to Week 06: Electronics Design.
Pcb production: refer to Week 08: PCB Production

Coding part: Made flow chart and used Chatgpt Ai prompt: Give a code for rp2040 connection on aurdino ide for the above connection. I was mesmerized by the code output that i received from chatgpt. As I read the code. the code read every bit well.

Once, I soldered the componenets and used the chatgpt generated code to power my input device code. At first the code didn't work.

Learnings: The code was pushed succesfully but didnt work perfectly. I realised the pin numbers needed to be changes. The biggest issue with the code was the aurdino Uno Library. The code that ai generated didnt include the libraried to run the code.

Later, I chose to go step by step to give the code. Fist I generated the code for the touch sensor. Ai i used code for Xaio . I mentioned pin numbers and other specifications as weel. Ai prompt:

                #define TOUCH_SENSOR_PIN D0  // Define the touch sensor pin
void setup() {
    Serial.begin(115200);  // Start serial communication
}
void loop() {
    int touchValue = analogRead(TOUCH_SENSOR_PIN);  // Read analog value
    Serial.print("Touch Sensor Value: ");
    Serial.println(touchValue);  // Print value to Serial Monitor
    delay(500);  // Small delay to prevent flooding
} 

Learnings: I burnt an RP2040.

Step Response

I referred to

Step response Link 1 and Andrian Toress Step response links to understand the how step response works.

Sensing with Step Response (transmit-receive, or tx-rx)

The transmit (TX) pin is alternately made high (5V or 3.3V) and low (0V). Note that the figures show values for 5V boards. For 3V boards (like ATSAM-based Adafruit boards), the highest voltage is 3.3V.

This process charges and discharges the TX electrode.

On the RX electrode, a small 'blip' (up or down) occurs as the TX pin toggles.

These blips are measured by the Arduino analog input (ADC), and the "low" value is subtracted from the "high" value.

This result varies depending on how closely the two plates are coupled by the electric field. It increases as the distance decreases and also changes with the amount of overlap and the material between the plates.