SIM800A GSM/GPRS Module

Name: SIM800A GSM/GPRS Module
Brand: ESP32
Price: 5.27 USD
Availability: InStock

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Overview

The SIM800A is a versatile GSM/GPRS module that provides dual-band connectivity for voice, SMS, and data applications. Its compact design and low power requirements make it suitable for a wide range of communication projects.

Quick Navigation

📋 Specs 📍 Pinout 🔌 Wiring 🔧 Debug

Code Examples

Arduino

C++ Framework

ESP-IDF

Native Framework

ESPHome

YAML Configuration

PlatformIO

IDE & Toolchain

MicroPython

Python Framework

About SIM800A GSM/GPRS Module

The SIM800A is a compact GSM/GPRS module designed for voice, SMS, and data transmission over dual-band (900/1800MHz) networks. With its small size and low power consumption, it is an excellent choice for wearables, IoT devices, and industrial automation.

⚡ Key Features

Dual-Band GSM (900/1800MHz) – Ensures reliable connectivity in supported regions.
Versatile Communication – Supports voice calls, SMS, and GPRS data transfer.
Multiple Interfaces – Includes UART and USB for seamless integration.
Compact & Low Power – Ideal for battery-powered and space-constrained applications.

🔗 Still deciding on a SIM module? Check the ESP32 SIM Modules Comparison Table for a breakdown of LTE, 3G, and GPRS options. 🚀

Where to Buy

Get Your SIM800A

Starting from

5.27$ per unit

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💡 Prices are subject to change. We earn from qualifying purchases as an Amazon Associate.

Technical Specs

SIM800A Specifications

Complete technical specification details for SIM800A GSM/GPRS Module

📊 Technical Parameters

Frequency Bands Dual-band 900/1800MHz

Supply Voltage 3.4V to 4.4V

Power Consumption (Sleep Mode) 1.0mA

Dimensions 24mm x 24mm x 3mm

Operating Temperature -40°C to +85°C

GPRS Connectivity GPRS multi-slot class 12

SIM Card Support 1.8V and 3V SIM cards

Interfaces UART, USB, SIM, GPIO

Download Full Datasheet

Pin Configuration

SIM800A Pinout

The SIM800A pinout includes power, UART communication, control, status indication, antenna connection, and SIM card interface pins for quad-band GSM/GPRS connectivity.

Visual Pinout Diagram

Pinout Diagram Primary

Total Pins

Pin Types

Power

Control

Quick Tips

Quad-band

GSM/GPRS module (850/900/1800/1900MHz),Supports voice calls, SMS, and GPRS data transfer,GPRS multi-slot class 12/10

GPRS

mobile station class B,Requires SIM card for cellular connectivity

Power

consumption: 2A peak during transmission,Default baud rate: 9600 bps (configurable via AT commands)

Pin Descriptions

Pin Name	Type	Description	Notes
1 VBAT	Power	Power supply input (3.4V to 4.4V)	Requires stable power supply with peak current up to 2A
2 GND	Ground	Ground connection	Connect to common ground
3 TXD	UART TX	UART Transmit Data (connects to microcontroller RX)	Default baud rate: 9600 bps
4 RXD	UART RX	UART Receive Data (connects to microcontroller TX)	Default baud rate: 9600 bps
5 PWRKEY	Control	Power on/off control (active low)	Pull low for at least 1 second to power on
6 RST	Control	Module reset (active low)	Pull low to reset the module
7 NETLIGHT	Status	Network status indication	LED indicator for network registration status
8 ANT	Antenna	Antenna connection	Requires external GSM antenna

Connection Guide

Wiring SIM800A to ESP32

Connect the SIM800A to your ESP32 via UART for AT command communication. The module requires a stable 3.4V-4.4V power supply with sufficient current capacity (peak 2A). An external GSM antenna is required for network connectivity.

Visual Wiring Diagram

Wiring Diagram Recommended

SIM800A GSM/GPRS Module wiring with ESP32

Connections

Connection Status

Required

Optional

Protocol

UART

Pin Connections

SIM800A Pin	ESP32 Pin	Description
1 VBAT Required	3.7V-4.4V Power Supply	Provide stable power (NOT from ESP32 pin)
2 GND Required	GND	Common ground connection
3 TXD Required	GPIO16 (RX2)	SIM800A TX to ESP32 RX
4 RXD Required	GPIO17 (TX2)	SIM800A RX to ESP32 TX
5 PWRKEY Optional	GPIO4	Power control (pull low to power on)
6 RST Optional	GPIO5	Module reset control
7 ANT Required	External GSM Antenna	Connect GSM antenna

⚠️

CRITICAL: Use a dedicated power supply (3.4V-4.4V, 2A peak) - DO NOT power from ESP32 pin!

Default

UART baud rate is 9600 bps

Use

logic level shifters if needed (though ESP32 is 3.3V compatible)

External

GSM antenna is mandatory for network connectivity

Pull

PWRKEY low for at least 1 second to power on the module

Monitor

NETLIGHT pin for network registration status

Insert

active SIM card before powering on

Ensure

good antenna placement for optimal signal reception

Help & Support

SIM800A Troubleshooting

Common issues and solutions to help you get your sensor working

Common Issues

Debugging Tips

Additional Resources

Datasheet

Technical specifications and guidelines

Code Examples

SIM800A Programming Examples

Ready-to-use code examples for different platforms and frameworks

#include <SoftwareSerial.h>

SoftwareSerial sim800a(10, 11); // RX, TX

void setup() {
    Serial.begin(9600);
    sim800a.begin(9600);

    // Power on the module
    pinMode(9, OUTPUT);
    digitalWrite(9, LOW);
    delay(1000); // PWRKEY needs to be low for at least 1 second
    digitalWrite(9, HIGH);
    delay(5000); // Wait for the module to initialize

    // Test AT communication
    sim800a.println("AT");
    delay(1000);
    while (sim800a.available()) {
        Serial.write(sim800a.read());
    }
}

void loop() {
    // Send an SMS
    sim800a.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim800a.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim800a.print("Hello from SIM800A");
    delay(1000);
    sim800a.write(26); // CTRL+Z to send SMS
    delay(5000);
}

This Arduino sketch interfaces with the SIM800A module using the SoftwareSerial library. The module is powered on by toggling the PWRKEY pin. An AT command is sent to verify communication. In the loop, the sketch sends an SMS by setting the module to SMS text mode, specifying the recipient's number, and sending the message, finalized with CTRL+Z (ASCII 26) to initiate transmission.

#include <stdio.h>
#include "driver/uart.h"
#include "driver/gpio.h"
#include "freertos/task.h"

#define TX_PIN 17
#define RX_PIN 16
#define PWRKEY_PIN 4
#define UART_PORT UART_NUM_1

void init_uart() {
    uart_config_t uart_config = {
        .baud_rate = 9600,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE
    };

    uart_param_config(UART_PORT, &uart_config);
    uart_set_pin(UART_PORT, TX_PIN, RX_PIN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
    uart_driver_install(UART_PORT, 1024, 0, 0, NULL, 0);
}

void power_on_sim800a() {
    gpio_set_direction(PWRKEY_PIN, GPIO_MODE_OUTPUT);
    gpio_set_level(PWRKEY_PIN, 0);
    vTaskDelay(1000 / portTICK_PERIOD_MS); // Hold PWRKEY low for 1 second
    gpio_set_level(PWRKEY_PIN, 1);
    vTaskDelay(5000 / portTICK_PERIOD_MS); // Wait for the module to initialize
}

void app_main(void) {
    init_uart();
    power_on_sim800a();

    char *test_cmd = "AT\r\n";
    uart_write_bytes(UART_PORT, test_cmd, strlen(test_cmd));

    while (true) {
        char data[128];
        int len = uart_read_bytes(UART_PORT, data, sizeof(data), 100 / portTICK_PERIOD_MS);
        if (len > 0) {
            data[len] = '\0';
            printf("Response: %s\n", data);
        }
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

This ESP-IDF example initializes UART communication with the SIM800A module and powers it on using the PWRKEY pin (GPIO4). The UART interface is configured with GPIO17 as TX and GPIO16 as RX. An AT command is sent to test communication, and responses from the module are printed to the console. The `power_on_sim800a()` function toggles the PWRKEY pin to activate the module.

uart:
  tx_pin: GPIO17
  rx_pin: GPIO16
  baud_rate: 9600

switch:
  - platform: gpio
    name: "SIM800A Power"
    pin:
      number: GPIO4
      inverted: true

switch:
  - platform: template
    name: "Send AT Command"
    turn_on_action:
      - uart.write: "AT\r\n"

sensor:
  - platform: custom
    lambda: |-
      return {nullptr};
    sensors:
      - name: "SIM800A Response"

The ESPHome configuration sets up UART communication with the SIM800A using GPIO17 (TX) and GPIO16 (RX) at 9600 baud. A GPIO-based switch is used to control the PWRKEY pin (GPIO4) for powering the module on or off. A template switch allows sending the AT command, and a custom sensor can be implemented to process responses from the module.

platformio.ini

[env:sim800a]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

main.cpp

#include <HardwareSerial.h>
#include <Arduino.h>

HardwareSerial sim800a(1);
#define PWRKEY 4

void power_on_sim800a() {
    pinMode(PWRKEY, OUTPUT);
    digitalWrite(PWRKEY, LOW);
    delay(1000); // Hold PWRKEY low for 1 second
    digitalWrite(PWRKEY, HIGH);
    delay(5000); // Wait for initialization
}

void setup() {
    Serial.begin(115200);
    sim800a.begin(9600, SERIAL_8N1, 16, 17); // RX, TX
    power_on_sim800a();

    // Test AT command
    sim800a.println("AT");
    delay(1000);
    while (sim800a.available()) {
        Serial.write(sim800a.read());
    }
}

void loop() {
    sim800a.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim800a.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim800a.print("Hello from PlatformIO");
    delay(1000);
    sim800a.write(26); // CTRL+Z to send SMS
    delay(5000);
}

This PlatformIO code interfaces with the SIM800A module using HardwareSerial on an ESP32. The `power_on_sim800a` function toggles the PWRKEY pin (GPIO4) to activate the module. The AT command is sent to test communication, and SMS functionality is implemented in the loop. GPIO16 (RX) and GPIO17 (TX) are configured as serial pins.

from machine import UART, Pin
import time

# Initialize UART
uart = UART(2, baudrate=9600, tx=17, rx=16)
pwrkey = Pin(4, Pin.OUT)

def power_on_sim800a():
    pwrkey.value(0)
    time.sleep(1)  # Hold PWRKEY low for 1 second
    pwrkey.value(1)
    time.sleep(5)  # Wait for module to initialize

def send_at(command):
    uart.write(command + '\r\n')
    time.sleep(1)
    while uart.any():
        print(uart.read().decode('utf-8'), end='')

# Power on the module
power_on_sim800a()

# Test communication
send_at('AT')

# Send SMS
send_at('AT+CMGF=1')  # Set SMS to text mode
send_at('AT+CMGS="+1234567890"')  # Replace with recipient's number
uart.write("Hello from MicroPython" + chr(26))

This MicroPython code communicates with the SIM800A module over UART. The `power_on_sim800a` function activates the module using the PWRKEY pin (GPIO4). The `send_at` function sends AT commands and prints the responses. The script initializes the module, tests communication, and sends an SMS with a specified message.

Summary

Wrapping Up SIM800A

The ESP32 SIM800A GSM/GPRS Module is a powerful SIM sensor that offers excellent performance and reliability. With support for multiple development platforms including Arduino, ESP-IDF, ESPHome, PlatformIO, and MicroPython, it's a versatile choice for your IoT projects.