This week's assignment is about Output Devices. Since my PCB fabrication is not yet completed, I am using an Arduino UNO to complete this week's work.
Output device example
An LED display is a module designed to display letters, numbers, and symbols. It is widely used in industrial applications such as digital clocks and temperature displays.I am using an I2C 1602A LCD.
Note: If the LCD backlight is too dim, adjust the blue potentiometer on the back of the LCD module.
The I2c 1602 LCD is a common 16Γ2 character liquid crystal display often used in embedded systems such as Arduino or microcontroller projects. It can display 2 rows with up to 16 characters per row. The common interface methods include parallel interface (4-bit or 8-bit mode) and I2C interface (via the PCF8574 expansion module).
Components Required: Arduino board, LED display module, and jumper wires.
Start β Initialize β Display "Hello WorldοΌ" on the LED screen β End
| LCD Pin | Arduino Uno Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| SDA | A4 |
| SCL | A5 |
The first time testing the code, the display did not show any content, so I used the following code to check the I2C Address.
#include <Wire.h>
void setup() {
Serial.begin(9600);
while (!Serial);
Serial.println("I2C Scanner is running...");
Wire.begin();
}
void loop() {
Serial.println("Scanning...");
byte count = 0;
for (byte address = 1; address < 127; address++) {
Wire.beginTransmission(address);
if (Wire.endTransmission() == 0) {
Serial.print("I2C device found at address 0x");
Serial.println(address, HEX);
count++;
}
delay(5);
}
if (count == 0) Serial.println("No I2C devices found!");
Serial.println("Scan complete.\n");
delay(5000);
}
lcd.backlight(); is called to turn on the display.The correct I2C address is foundοΌ0x27οΌ, use the following test code:
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() {
lcd.init();
lcd.backlight();
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Hello, World!");
}
void loop() {}
Unfortunately,there was still no display content. I continued troubleshooting and found that the contrast needed to be adjusted. Finally, the test was completed.
This device uses the DS18B20 sensor as the temperature input and an I2C 1602 LCD as the output display.
DS18B20 is a common digital temperature sensor that uses a unique single-wire interface. Compared to analog temperature sensors, it is more functional, simple in hardware, easy to expand, and highly resistant to interference.
| Feature | Specification |
|---|---|
| Power Supply | DC 5V |
| Temperature Range | -55 to +125β |
| Communication Interface | 1-Wire |
| Accuracy | Β±0.5β |
| Resolution | 9-12 bits adjustable |
The pin configuration is as follows:
| Pin | Description |
|---|---|
| VCC | Power Supply (5V) |
| GND | Ground |
| I/O | Data Line |
The following Arduino code reads temperature from the DS18B20 sensor and displays it on an I2C 1602 LCD:
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <OneWire.h>
#include <DallasTemperature.h>
// LCD setup
LiquidCrystal_I2C lcd(0x27, 16, 2);
// DS18B20 setup
#define ONE_WIRE_BUS 2
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
void setup() {
lcd.init();
lcd.backlight();
sensors.begin();
lcd.setCursor(0, 0);
lcd.print("Temp Monitor");
}
void loop() {
sensors.requestTemperatures();
float temperatureC = sensors.getTempCByIndex(0);
lcd.setCursor(0, 1);
lcd.print("Temp: ");
lcd.print(temperatureC);
lcd.print(" C ");
delay(1000);
}
Tools β Board and select your Arduino Uno.Tools β Port and select the correct port COM5.Tools β Serial Monitor .(shift+alt+M)