Feature: RF design
Inputs IN1-4 of the relay board are connected to port pins 2-5
of the Arduino, respectively. Also, the Arduino GND and +3.3V pins are connected to the GND and VCC
pins of the relay board. Make sure that jumper JD an external +5V power supply to the JD
is removed from the board, and connect -VCC
Program listing In this project, the connectionless UDP protocol is used to send commands over Wi-Fi to control the relays remotely from an Android smartphone. Te following are the valid commands:
n = ON n = OFF
Figure 2: Four-channel relay board
Turn on relay n, where n = 1 to 4 Turn off relay n, where n= 1 to 4
For example, entering command 2 = ON on the smartphone will activate relay 2 (Figure 5). Similarly, sending command 2 = OFF will deactivate relay 2. Figure 6 shows the Arduino Uno R4 Wi-Fi program listing. Te
module header files are included at the beginning of the program. Wi-Fi SSID and password are entered and port is set to 5000. Inside the setup() function, relay inputs IN1-4 are configured
pin of the relay board.
Figure 3: Arduino Uno R4 Wi-Fi board
development board (Figure 3), released only a few months ago. Its basic features include: • Wi-Fi 2.4GHz, 802.11b/g/n, up to 150Mbit/s; • Bluetooth LE and Bluetooth 5; • Built-in antenna; • 12 x 8 LED matrix; • Connector to add external battery to a real-time clock; • Qwicc-style connector for 3.3V I2 MCU);
• Secondary 240MHz, 3.3V dual-core 32-bit Espressif ESP32-S3- MINI-1-N8 processor;
• 384kbyte ROM; • 512kbyte RAM; • On-board programmable header; • VRTC
Figure 4: Circuit diagram of the project
C (additional channel from the Figure 5:
Command sent to turn ON relay 2
pin for external RTC battery. Te circuit diagram of the project is shown in Figure 4, where
a 4-way relay board is connected to the Arduino Uno R4 Wi-Fi board.
20 February 2024
www.electronicsworld.co.uk
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