9. Input devices¶
A Hero Shot !
Group Assignment¶
For more details, visit our lab site: Tech Works - Input devices
We started by testing various analog and digital sensors using the Arduino Uno and plotting their outputs using the Arduino Serial Plotter.
Infrared Speed Sensor¶
The Infrared Speed Sensor consists of an IR transmitter and receiver. When an obstacle is placed between these sensors, the reading will be “0”, and when there is nothing in between, the reading will be “1”.
We connected the sensor to the Arduino and plotted the output. When there is no object between the photo diode and phototransistor, the output is zero, and when an object is present, the output becomes one.
NTC (Thermistor)¶
The NTC thermistor is a type of variable resistor whose resistance changes with the temperature. NTC stands for Negative Temperature Coefficient.
We connected the sensor to the Arduino and plotted the output. When we brought the soldering iron close to the thermistor, the resistance of the thermistor decreased, causing a higher voltage to be measured.
Encoder¶
The encoder is a position sensor that generates electrical signals to track the angular position and direction of a rotating shaft.
We connect this sensor to the Arduino by connecting the GND and 5V pins to the corresponding ground and power pins on the Arduino, and the CLK pin to a PWM-capable pin (pin 3). Each time the encoder moves one step, it generates a pulse, as shown below.
Individual Assignment¶
PCB Design and CNC Production¶
This week i built a new board basically i just add headers with the XIAO RP2040 so i could use it in different general use.
I used Altium Designer to design my board I used the same procedure explained in Week6-Electronics Design the new thing i did that i make my oun footprint for the smd headers as well i make the board in circular shape.
I used ModsCE to cut the board same procedure used in Week8-Electronics Production.
Adding headers footprint:
It tooks me lot of time in searching on Header-Female-2.54_1x9 footprint but i didn’t found while I found a one but it was through hole so I decided to install it and make modification on the pad footprint.
1️⃣ after installing the library I changed the pads’ layer into top layer rather than multi layer.
2️⃣ changed the pads’ chape from circular into rectangular.
Making the board circular:
1️⃣ I draw a circle at the middle of my PCB design
2️⃣ from design .. board chape.. define board chape from selected object
📌Failed PCB After cutting the board i figured out that it didn’t cuts two pads correctly due to the small amount between the pads and a trace i were place.
How I solved this issue:
I had two choices whether to manually cut a gap between the two adherent pads using scalpel , or to re design it using a 0 ohm resistor which was an advice by my colleague so i choose to re design the board caus it’s more efficent way.
IR Infrared Sensor¶
It consists of photo diode “IR transmitter” and photo transistor “IR receiver” ,The IR transmitter continuously emits the IR light and the IR receiver keeps on checking for the reflected light. If the light gets reflected back by hitting any object in front it, the IR receiver receives this light.
Wiring (1)leg to 5V (Power) (2)leg to GND (3)leg split to D0
#define Sensor 26
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
pinMode(Sensor,INPUT);
}
void loop() {
// put your main code here, to run repeatedly:
int Sread = digitalRead (Sensor);
Serial.println(Sread);
delay(100);
}
LDR¶
A light dependent resistor(LDR) is used to detect the presence or level of light. It consist of a resistor when light falls on the LDR then the resistance decreases, and increases in the dark.
Wiring (1)leg to 5V (Power) (2)GND with 10k Ohm resistor (3)leg split to A1 and the resistor
this based on the voltage divider rule
Plotting the LDR analog signal
#define Sensor A0
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
pinMode(Sensor,INPUT);
}
void loop() {
// put your main code here, to run repeatedly:
int Sread = analogRead (Sensor);
Serial.println(Sread);
delay(100);
}
Then I connect the LDR with XIAO and controlled the built in led I placed on pin (P26) i want to represent the phone display brightness how works so when its lights up the led turn on and when its dark the led stays off.
Files
