Week 9. Group / Input Devices¶

This is group assignment page for West harima student :

Student¶

Koharu Takeda

group assignment¶

probe an input device’s analog levels and digital signals

Touch sensor¶

What is Touch sensor

A touch sensor is a sensor that reacts to human touch. They are used in touch panels, switches, elevators, emergency stop buttons on machines, etc.

TTP223

datasheet

This time I used this touch sensor.

alt text

FEATURES
- Operating voltage 2.0V~5.5V
- Operating current @VDD=3V, no load, SLRFTB=1
- At low power mode typical 1.5uA, maximum 3.0uA At fast mode typical 3.5uA, maximum 7.0uA @VDD=3V, no load, SLRFTB=0
- At low power mode typical 2.0uA, maximum 4.0uA At fast mode typical 6.5uA, maximum 13.0uA
- The response time max about 60mS at fast mode, 220mS at low power mode @VDD=3V
- Sensitivity can adjust by the capacitance(0~50pF) outside
- Have two kinds of sampling length by pad option(SLRFTB pin)
- Stable touching detection of human body for replacing traditional direct switch key
- Provides Fast mode and Low Power mode selection by pad option(LPMB pin)
- Provides direct mode、toggle mode by pad option(TOG pin)
  - Open drain mode by bonding option, OPDO pin is open drain output,
  - Q pin is CMOS output
- All output modes can be selected active high or active low by pad option(AHLB pin)
- Have the maximum on time 100sec by pad option(MOTB pin)
- Have external power on reset pin(RST pin)
- After power-on have about 0.5sec stable-time, during the time do not touch the key pad,and the function is disabled
- Auto calibration for life and the re-calibration period is about 4.0sec, when key has not be touched

1.serial monitor(Touch sensor)¶

Board : XIAO ESP32S3 (made in week8)

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Seeed Xiao ESP32S3 pinout

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1.0 programming

This time I used the program below with the Arduino IDE.

select board

tool > Board > esp32 > XIAO_ESP32S3

select tool

tool > port > /dev/cu.usbmodem14201

source code

reference:Touch Sensor Module

Only the board type and pin settings used have been changed.

/*
  A simple code to read input from a touch sensor
  connected to pin D0 of an XIAO ESP32S3 Development Board.

  Board: XIAO ESP32S3 Development Board
  Component: Touch Sensor
*/

// Define the pin used for the touch sensor
const int sensorPin = D0;

void setup() {
  pinMode(sensorPin, INPUT);     // Set the sensor pin as input
  Serial.begin(9600);            // Start the serial communicatio
}
void loop() {
  if (digitalRead(sensorPin) == 1) {  // If the sensor is touched
    Serial.println("Touch detected!");
  } else {
    Serial.println("No touch detected...");
  }
  delay(100);  // Wait for a short period to avoid rapid reading of the sensor
}

1.1 Enter the program and observe the values in Serial Monitor.

Monitor

2.LED blink¶

2.0 We tried programming the LED to light up when the touch sensor responds. This code is based on the above code, and I asked chatGPT to write a program to light up the LED when the sensor detects it.(ChatGPT-4o mini)

/*
  A simple code to control an LED connected to pin D9
  based on the input from a touch sensor connected to pin D0.

  Board: ESP32 Development Board
  Components: Touch Sensor (D0), LED (D9)
*/

// Define the pin used for the touch sensor and LED
const int sensorPin = D0;  // Touch sensor connected to pin D0
const int ledPin = D9;     // LED connected to pin D9

void setup() {
  pinMode(sensorPin, INPUT);   // Set the sensor pin as input
  pinMode(ledPin, OUTPUT);     // Set the LED pin as output
}

void loop() {
  if (digitalRead(sensorPin) == 1) {  // If the sensor is touched
    digitalWrite(ledPin, HIGH);  // Turn on the LED
  } else {
    digitalWrite(ledPin, LOW);   // Turn off the LED
  }
  delay(100);  // Wait for a short period to avoid rapid reading of the sensor
}

LED blink

Step response¶

What is step response

The step-response is a sensor that is made with two sheets of copper, separated from each other by a porous insulating material. It can be used to calculate the value of force, weight, resistance…

3.Serial Plotter(Step response)¶

Board

Fab XIAO_XIAO ESP32C3(by Adrian design)
Board for step response(by Adrian design)

alt text

Seeed Xiao ESP32C3 pinout

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3.0 Two electrodes

Electrodes of copper foil tape (100x100mm of 0.03mm thickness) are made on an acrylic board. A non-slip sheet was placed in between.

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3.1 programming

This time I used the program below with the Arduino IDE.

source code

reference:Adrian’s site

In this case, it was used as is.

//tx_rx03  Robert Hart Mar 2019.
//https://roberthart56.github.io/SCFAB/SC_lab/Sensors/tx_rx_sensors/index.html

//Modified by Adrián Torres Omaña
//Fab Academy 2023 - Fab Lab León
//Step Response TX, RX
//Fab-Xiao

//  Program to use transmit-receive across space between two conductors.
//  One conductor attached to digital pin, another to analog pin.
//
//  This program has a function "tx_rx() which returns the value in a long integer.
//
//  Optionally, two resistors (1 MOhm or greater) can be placed between 5V and GND, with
//  the signal connected between them so that the steady-state voltage is 2.5 Volts.
//
//  Signal varies with electric field coupling between conductors, and can
//  be used to measure many things related to position, overlap, and intervening material
//  between the two conductors.
//


long result;   //variable for the result of the tx_rx measurement.
int analog_pin = A1; //  GPIO 27 of the XIA0 RP2040 or ESP32-C3 pin A1
int tx_pin = D2;  //     GPIO 28 of the XIAO RP2040 or ESP32-C3 pin D2
void setup() {
pinMode(tx_pin,OUTPUT);      //Pin 2 provides the voltage step
Serial.begin(115200);
}


long tx_rx(){         //Function to execute rx_tx algorithm and return a value
                      //that depends on coupling of two electrodes.
                      //Value returned is a long integer.
  int read_high;
  int read_low;
  int diff;
  long int sum;
  int N_samples = 100;    //Number of samples to take.  Larger number slows it down, but reduces scatter.

  sum = 0;

  for (int i = 0; i < N_samples; i++){
   digitalWrite(tx_pin,HIGH);              //Step the voltage high on conductor 1.
   read_high = analogRead(analog_pin);        //Measure response of conductor 2.
   delayMicroseconds(100);            //Delay to reach steady state.
   digitalWrite(tx_pin,LOW);               //Step the voltage to zero on conductor 1.
   read_low = analogRead(analog_pin);         //Measure response of conductor 2.
   diff = read_high - read_low;       //desired answer is the difference between high and low.
 sum += diff;                       //Sums up N_samples of these measurements.
 }
  return sum;
}                         //End of tx_rx function.


void loop() {

result = tx_rx();
result = map(result, 17000, 23000, 0, 64);  //I recommend mapping the values of the two copper plates, it will depend on their size
Serial.println(result);
delay(100);
}

To observe the response more clearly, we scaled result = map from 0 to 64.

3.2 Enter the program and observe the values in Serial Plotter.

hand

Pinball

result
hand	Response. The waves were large and easy to understand.
pinball	It appears to be responding, but I can’t tell for sure.

Sonar¶

What is sonar

sonar is a sensor that uses ultrasonic waves to detect distance and object location.

4.serial monitor(sonar)¶

Board

XIAO ESP32S3 (made in week8)
Connection

alt text

Seeed Xiao ESP32S3 pinout

alt text

I used HC-SR04 for this project.

alt test

FEATURES
Working Voltage	DC 5 V
Working Current	15mA
Working Frequency	40Hz
Max Range	4m
Min Range	2cm
MeasuringAngle	15 degree
Trigger Input Signal	10uS TTL pulse
Echo Output Signal	Input TTL lever signal and the proportion
Dimension	452015mm

4.0 programming

This time I used the program below with the Arduino IDE.

source code

reference:Try using ultrasonic sensors to measure distance and detect obstacles! [HC-SR04]

I edited only the settings for the pins I use.

// Arduino Beginner Guide ⑪ Measuring Distance with Ultrasonic Sensor HC-SR04
// https://burariweb.info

#define trigPin  D4 // Set trigger pin to D4
#define echoPin  D5 // Set echo pin to D5

float Duration = 0;  // Measured time
float Distance = 0;  // Distance

void setup(){

  Serial.begin(9600);  // Start serial monitor

  pinMode(echoPin,INPUT);   // Set echo pin as input
  pinMode(trigPin,OUTPUT);  // Set trigger pin as output

}

void loop(){

  digitalWrite(trigPin,LOW);              // Set trigger pin LOW before measurement
  delayMicroseconds(2);

  digitalWrite(trigPin,HIGH);             // Set trigger pin HIGH for 10μs
  delayMicroseconds(10);
  digitalWrite(trigPin,LOW);

  Duration = pulseIn(echoPin,HIGH);      // Read input from echo pin

  Duration = Duration / 2;               // Divide time by 2
  Distance = Duration * 340 * 100 / 1000000;   // Multiply by speed of sound to get cm

  if(Distance >= 400 || Distance <= 2){  // Handle out-of-range measurements

    Serial.println("Distance = Out of range");

  }

  else{
    Serial.print("Distance ");            // Display distance on serial monitor
    Serial.print(Distance);
    Serial.println(" cm");

  }

  delay(100);

}

4.1 Enter the program and observe the values in Serial Monitor.

In fact, this process was very time consuming. Because I tried many programs, but the sensor did not respond very well. The reason why it did not respond was a bad solder on the board I made in week8. It took me a lot of time to realize this…
It was already tested with a multimeter after it was made by week8, but it seems that a solder defect was missed.

Debug
problem	The value does not change and continues to display 0.
cause	solder defect
solution	Resolder again and check for continuity.

Reference Links¶

Touch Sensor Basic Program(in Japanese)
Touch Sensor Module(in Japanese)
Touch sensor with ESP32(in Japanese)
How to use HC-SR04(in Japanese)
Try using ultrasonic sensors to measure distance and detect obstacles.(in Japanese)
Adrian’s site(Fab-XIAO)

Impressions　and What’s I learned¶

We learned that there are various types of Input Devices.
In the step response, the response was good when pressed by hand, but it was difficult to tell the response when done with a pinball.
I learned how hard it is to debug the serial monitor (Ultrasonic sensor) and how important it is to work carefully to get to that point. It really took a long time this time…
With the touch sensor, it was possible to observe whether the sensor was touched or not, but with the step response, it was possible to observe not only whether the sensor was touched or not, but also the changes in value that occurred in between.

Week 9. Group / Input Devices¶

Student¶

group assignment¶

Touch sensor¶

1.serial monitor(Touch sensor)¶

2.LED blink¶

Step response¶

3.Serial Plotter(Step response)¶

Sonar¶

4.serial monitor(sonar)¶

Reference Links¶

Impressions and What’s I learned¶

Impressions　and What’s I learned¶