Circuit Documentation

Summary of the Circuit

This circuit is designed to interface an Arduino Nano with a SIM800L GSM module and a 4-channel 5V relay module. It is powered by a USB power source, and an electrolytic capacitor is used for power stabilization. The Arduino Nano controls the relay module and communicates with the SIM800L module for GSM operations.

Component List

Arduino Nano

• Microcontroller board based on the ATmega328P
• It has a variety of digital and analog I/O pins
• Used for controlling the relay module and communicating with the SIM800L GSM module

Relay 4 Channel 5v

• A 4-channel relay module that operates at 5V
• Allows for controlling high power devices with Arduino's low power signals
• Each channel has a Normally Open (NO) and a Normally Closed (NC) contact

Electrolytic Capacitor

• A polarized capacitor with a specific capacitance
• Used for power supply filtering to reduce voltage spikes and noise

Sim800l

• A GSM/GPRS module that allows for cellular communication
• Can be used for sending SMS, making calls, or connecting to the internet

USB Power

• Provides power to the circuit
• Typically outputs 5V and can be sourced from a computer USB port or a USB power adapter

Wiring Details

Arduino Nano

• D2 connected to SIM800L RXD
• D3 connected to SIM800L TXD
• D4 connected to Relay Module IN1
• D5 connected to Relay Module IN2
• D6 connected to Relay Module IN3
• D7 connected to Relay Module IN4

Relay 4 Channel 5v

• GND connected to common ground net
• VCC connected to common power net
• IN1 to IN4 controlled by Arduino Nano digital pins D4 to D7

Electrolytic Capacitor

• + connected to common power net
• - connected to common ground net

Sim800l

• RXD connected to Arduino Nano D2
• TXD connected to Arduino Nano D3
• VCC connected to common power net
• GND connected to common ground net

USB Power

• + connected to common power net
• - connected to common ground net

Documented Code

Arduino Nano Code (sketch.ino)

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

Note: The provided code is a template and does not contain any functional code. It needs to be populated with the logic to control the relay module and communicate with the SIM800L module.