9. Input Devices

This week I worked on making a device using analog input.

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Group assignment:

• Probe an input device(s)’s analog levels and digital signals
• Document your work on the group work page and reflect on your individual page what you learned

Individual assignment:

• Measure something: add a sensor to a microcontroller board that you have designed and read it.

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Group Assignment

This week’s group work page is here

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Individual Assignment

Basic Idea

This week I’d like to try analog input using slider, because slider movement may be used in my final project. I will make color changing LED with sliders.

Design

I made the board connecting with 3 sliders and xiao putting board. I put 9 females pins in center for sliders. Wires had been grouped by functions, as each slider has 3 headers(Data,VCC,GND).

After finishing the design, 2exported files are made(week9-F_Cu.svg, week9-B_Cu.svg).

Milling

Before starting mods application, we had to make 3 functional files as there are holes in the board.
(See “HOW TO MAKE MILLING DATA FILE WITH HOLES” in week8-page for detail)

I made 3 milling data files(toolpath design, hole design, and outside line design), before mods application is started.

📌 I made a mistake in making holes. The holes were too big, because wrong mill data file was set.

So I made another holes’ milling file with checking the procedure.

Files	Invert	Endmill size
Toolpath File	Do Invert	1/64
Holes File	x	1/32
Outline File	x	1/32

Soldering

I put the 9 female sockets for putting cables from sliders,1 3-male pinheader for the slider values, and 2-male pinheaders for ground and vcc. I used 0Ω resistors as a jumper for the first time.

Test

I had several tests for connecting and working properly.

1) Connecting check with xiao and LED
First I checked the connection with simple LED.

1) Check if slider is connecting and sending the value
First, one slider is connected with pcb board and “xiao” board. Then I checked analog input value by sliding with arduino ide.

The code I used is as follows:

const int InputPin = A0;
int anaval = 0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {

  // put your main code here, to run repeatedly:
  pinMode(InputPin,INPUT);
  //analogWrite(10,255);
  anaval = analogRead(InputPin);
  Serial.print("input value:");
  Serial.println(anaval);

  delay(1000);

}

When I run this program, the value is displayed and values are changed by sliding.

1) Test all the components are connected
At last, I connected 3 sliders, xiao and RGB fullcolored LED, and test if it works. The code I wrote was at “Code” below.

Result

RGB color was assigned to each slider and it was successfully changed the color and brightness of the LED depending on the value of the slider.

Code

Input: analog value from each slider

Output: LED

/*
  Analog input, analog output
*/

// These constants won't change. They're used to give names to the pins used:
const int analogInPin1 = A0;  // Analog input pin that the potentiometer is attached to
const int analogInPin2 = A1;  // Analog input pin that the potentiometer is attached to
const int analogInPin3 = A2;  // Analog input pin that the potentiometer is attached to

const int OutPin1 = D10;  // Analog output pin that the LED is attached to
const int OutPin2 = D9;  // Analog output pin that the LED is attached to
const int OutPin3 = D8;  // Analog output pin that the LED is attached to

int digi_min = 0;       // Digital min value
int ana_min = 0;        // Analog min value
int digi_max = 255;     // Digital max value
int ana_max = 1023;     // Analog max value

// Initial value
int sensorValue1 = 0;  // value read from the pot
int outputValue1 = 0;  // value output to the PWM (analog out)
int sensorValue2 = 0;  // value read from the pot
int outputValue2 = 0;  // value output to the PWM (analog out)
int sensorValue3 = 0;  // value read from the pot
int outputValue3 = 0;  // value output to the PWM (analog out)

void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600);
}

void loop() {

  // read analog in value and return digital value  
  outputValue1 = ana_digi_Valchange(analogInPin1);
  outputValue2 = ana_digi_Valchange(analogInPin2);
  outputValue3 = ana_digi_Valchange(analogInPin3);

  // Set the pin
  pinMode(OutPin1,OUTPUT);
  pinMode(OutPin2,OUTPUT);
  pinMode(OutPin3,OUTPUT);

  // analog writing
  analogWrite(OutPin1,outputValue1);
  analogWrite(OutPin2,outputValue2);
  analogWrite(OutPin3,outputValue3);

   delay(500);
}

int ana_digi_Valchange(int anaPin){   //input:analog pinNo, Output Value, 
  int sensorVal;
  int OutVal;

  // read the analog in value:
  sensorVal = analogRead(anaPin);

 // Debug
  Serial.print(sensorVal);
  Serial.print(",");

  // Map
  OutVal = map(sensorVal, ana_min, ana_max, digi_min, digi_max);
  return(OutVal);
}

Research

I studied and researched about analog input, and also checked the function of RGB full colored LED. I’ve learned about “Common Anode” and “Common Cathode” through RGB full colored LED has it.

I’ve got an idea from ChatGPT.

Common Anode vs. Common Cathode

Understanding Anode and Cathode

• Anode (+) → Connect to positive voltage (VCC) to turn on.
• Cathode (-) → Connect to ground (0V) to complete the circuit.

Common Anode (CA)

• Anode is shared and connected to VCC (+).
• LEDs turn on when cathode (-) is set to LOW (0V).
• Used when controlling LEDs with LOW signals.

Common Cathode (CC)

• Cathode is shared and connected to GND (0V).
• LEDs turn on when anode (+) is set to HIGH (VCC).
• Easier to use with microcontrollers like Arduino.

Summary Table

Type	Anode (+) Connection	Cathode (-) Connection	How to Turn On LEDs?
Common Anode (CA)	Connected to VCC (+)	Controlled by LOW (0V)	Output LOW to turn on
Common Cathode (CC)	Controlled by HIGH (+)	Connected to GND (0V)	Output HIGH to turn on

Choosing the Right Type

• Use Common Cathode (CC) for simple control with microcontrollers.
• Use Common Anode (CA) when working with circuits that prefer LOW signals.

Links

• The LED Studio