SIM7600 Arduino: 4G LTE Cellular IoT Projects

As wireless connectivity becomes essential for embedded systems and IoT applications, the transition from 2G to 4G LTE technology has opened new possibilities for remote monitoring, data transmission, and cellular communication. The SIM7600 Arduino combination represents a powerful solution for engineers developing cellular-connected projects, offering reliable 4G LTE connectivity where WiFi isn’t available.

With 2G networks shutting down across multiple regions including Australia, Canada, and parts of Europe, designers are rapidly migrating to 4G LTE modules like the SIM7600. This guide provides practical insights from a PCB design perspective, covering hardware interfaces, software libraries, real-world project implementations, and troubleshooting techniques that work.

Understanding the SIM7600 4G LTE Module

The SIM7600 series represents SIMCom’s latest generation of multi-band LTE cellular modules designed specifically for IoT applications. These modules bridge the gap between legacy 2G/3G systems and modern 4G networks, providing backward compatibility while delivering significantly improved data speeds and network coverage.

Technical Specifications Overview

The SIM7600 comes in two main categories based on LTE performance capabilities:

Feature	SIM7600 (Cat-1)	SIM7600-H (Cat-4)
Downlink Speed	Up to 10 Mbps	Up to 150 Mbps
Uplink Speed	Up to 5 Mbps	Up to 50 Mbps
Form Factor	LCC (87 pins)	LCC (87 pins)
Operating Voltage	3.4V – 4.2V	3.4V – 4.2V
Peak Current	2A	2A
Operating Temperature	-40°C to +85°C	-40°C to +85°C

Supported Network Technologies

Technology	Frequency Support
LTE-FDD	Varies by region (B1/B2/B3/B4/B5/B7/B8/B20/B28)
LTE-TDD	B38/B39/B40/B41
WCDMA	850/900/1900/2100 MHz
GSM	850/900/1800/1900 MHz

The multi-band support allows for global deployment, but regional variants like SIM7600A (Americas), SIM7600E (Europe), and SIM7600G (Global) optimize frequency bands for specific markets.

Integrated GPS/GNSS Positioning

Beyond cellular connectivity, the SIM7600 integrates multi-constellation GNSS positioning supporting:

• GPS (USA)
• GLONASS (Russia)
• BeiDou (China)
• Galileo (Europe)

This built-in positioning capability eliminates the need for separate GPS modules in vehicle tracking, asset monitoring, and location-based IoT applications.

Hardware Interface Design for Arduino Integration

Power Supply Considerations

One of the most critical aspects of SIM7600 Arduino interfacing involves proper power supply design. The module can draw up to 2A during network registration and data transmission peaks, which exceeds typical USB port capabilities by 4x.

Power Supply Requirements:

• Minimum supply voltage: 3.4V
• Nominal supply voltage: 3.8V (recommended)
• Maximum supply voltage: 4.2V
• Peak current: 2A
• Average current (idle): 25mA

From a PCB design perspective, the power supply circuit should include:

1. Low ESR capacitors (330μF to 470μF electrolytic + 100nF ceramic) placed close to VBAT pins
2. Power supply capable of sourcing sustained 2A current
3. Voltage monitoring circuit for under-voltage detection
4. Optional battery backup using 3.7V Li-ion cells

Many Arduino boards cannot provide the required current through their 5V or 3.3V rails. External power supplies or battery packs are mandatory for stable operation.

UART Serial Communication

The SIM7600 communicates with Arduino microcontrollers primarily through UART serial interface at 115200 baud rate (default). However, there’s a critical voltage level consideration:

Voltage Level Translation:

The SIM7600 RX/TX pins operate at 1.8V logic levels, while most Arduino boards use 3.3V or 5V logic. Direct connection will damage the module. Three solutions exist:

1. Level shifter ICs (BSS138-based bidirectional shifters)
2. Voltage divider for Arduino TX to module RX (simple resistor divider)
3. Pre-built modules with integrated level shifting (Maduino Zero, Waveshare shields)

Pin Configuration Reference

SIM7600 Pin	Function	Arduino Connection	Notes
RX	Serial Receive	TX (with level shift)	1.8V logic
TX	Serial Transmit	RX (with level shift)	1.8V logic
PWRKEY	Power Key	Digital Pin	Active LOW (1-2s pulse)
RESET	Reset	Digital Pin	Active LOW
STATUS	Network Status	Digital Pin (Input)	LED indicator
DTR	Data Terminal Ready	Digital Pin	Sleep control
RI	Ring Indicator	Digital Pin (Input)	Incoming call/SMS

Antenna Connections

Proper antenna design significantly impacts cellular performance:

• Main LTE Antenna: SMA connector, 50Ω impedance
• Diversity Antenna: Optional for improved reception
• GPS/GNSS Antenna: Active antenna requiring 2.85V power supply

RF trace routing requires careful impedance control (50Ω) and proper ground plane design to minimize signal loss and EMI.

Arduino Software Libraries and Setup

TinyGSM Library – The Standard Solution

TinyGSM has emerged as the industry-standard Arduino library for cellular modules including SIM7600. This lightweight library provides standardized Arduino Client interface for GPRS/LTE data connections.

Key Features:

• Small memory footprint (significantly smaller than Arduino GSM library)
• Supports multiple modem types with unified API
• Non-blocking architecture where practical
• Built-in auto-bauding capability
• Standard Arduino Client interface compatibility

Installation Process:

// Arduino IDE: Sketch > Include Library > Manage Libraries

// Search: “TinyGSM” and click Install

Basic TinyGSM Implementation:

#define TINY_GSM_MODEM_SIM7600  // Define modem type

#define TINY_GSM_RX_BUFFER 1024  // Set RX buffer size

#include <TinyGsmClient.h>

// Hardware Serial for ESP32

#define SerialAT Serial1

#define SerialMon Serial

// APN settings (carrier specific)

const char apn[] = “your-apn-here”;

const char gprsUser[] = “”;

const char gprsPass[] = “”;

TinyGsm modem(SerialAT);

TinyGsmClient client(modem);

void setup() {

  SerialMon.begin(115200);

  SerialAT.begin(115200);

  // Restart modem

  SerialMon.println(“Initializing modem…”);

  modem.restart();

  // Wait for network

  SerialMon.print(“Waiting for network…”);

  if (!modem.waitForNetwork()) {

    SerialMon.println(” fail”);

    while (true);

  }

  SerialMon.println(” OK”);

  // Connect to GPRS

  SerialMon.print(“Connecting to “);

  SerialMon.print(apn);

  if (!modem.gprsConnect(apn, gprsUser, gprsPass)) {

    SerialMon.println(” fail”);

    while (true);

  }

  SerialMon.println(” OK”);

}

AT Command Alternative Approach

For projects requiring more direct control or when TinyGSM doesn’t fit requirements, native AT commands provide complete module access.

Essential AT Commands:

Command	Function	Response
AT	Test connection	OK
ATI	Module information	Module details
AT+CPIN?	Check SIM status	+CPIN: READY
AT+CSQ	Signal quality	+CSQ: rssi,ber
AT+CREG?	Network registration	+CREG: status
AT+CGATT=1	Attach GPRS	OK
AT+CGDCONT=1,”IP”,”apn”	Set APN	OK
AT+CGACT=1,1	Activate PDP context	OK

Arduino Board Compatibility

Directly Compatible Boards:

• Maduino Zero 4G LTE: ATSAMD21G18A-based, Arduino Zero compatible with integrated SIM7600
• ESP32 boards: Popular choice due to dual-core processing and ample memory
• Arduino Mega 2560: Multiple hardware serial ports beneficial
• Arduino Due: 3.3V logic simplifies level shifting

Requires Adaptation:

• Arduino Uno/Nano: Limited to SoftwareSerial, requires level shifting, tight memory constraints
• Arduino Leonardo: USB conflicts possible, careful serial port management needed

Common Compilation Issues and Solutions

Engineers frequently encounter specific compilation errors when working with SIM7600 Arduino projects:

Issue 1: SerialUSB Not Declared

error: ‘SerialUSB’ was not declared in this scope

Solution: SerialUSB only exists on SAMD-based boards (Arduino Zero/Due). Replace with Serial on AVR boards (Uno/Mega).

Issue 2: Memory Overflow

Arduino Uno’s 2KB RAM can overflow with TinyGSM. Solutions:

• Reduce TINY_GSM_RX_BUFFER size
• Upgrade to boards with more memory (ESP32, Mega)
• Implement custom lightweight AT command parser

Issue 3: Baud Rate Communication Failures

If AT commands return gibberish:

• Verify 115200 baud rate on both sides
• Check level shifting circuit
• Try auto-bauding sequence
• Reduce to 9600 baud if issues persist

Real-World IoT Project Implementations

Project 1: Remote Environmental Monitoring with HTTP POST

This project demonstrates sending DHT11 temperature and humidity data to ThingSpeak cloud platform using HTTP POST requests.

Hardware Requirements:

• SIM7600 module (any variant)
• Arduino-compatible board (ESP32 recommended)
• DHT11 temperature/humidity sensor
• Power supply (5V 2A minimum)
• 4G SIM card with data plan

Implementation Approach:

The system reads environmental data every 60 seconds and transmits it to ThingSpeak server using SIM7600’s built-in HTTP client functionality.

// HTTP POST Implementation

String http_url = “http://api.thingspeak.com/update?api_key=” +

                  apiKey +

                  “&field1=” + String(temperature) +

                  “&field2=” + String(humidity);

sendData(“AT+HTTPINIT”, 1000, DEBUG);

sendData(“AT+HTTPPARA=\”URL\”,\”” + http_url + “\””, 1000, DEBUG);

sendData(“AT+HTTPACTION=0”, 2000, DEBUG);  // GET request

sendData(“AT+HTTPTERM”, 1000, DEBUG);

Key Learning Points:

• APN configuration varies by carrier
• HTTP timeout handling is critical
• Network registration can take 30-90 seconds on cold boot
• Data transmission success should be verified with AT+HTTPACTION response codes

Project 2: MQTT-Based Sensor Network

MQTT protocol provides lightweight publish-subscribe messaging ideal for IoT applications. The SIM7600 includes built-in MQTT stack accessible through AT commands.

MQTT AT Command Workflow:

Step	AT Command	Purpose
1	AT+CMQTTSTART	Start MQTT service
2	AT+CMQTTACCQ=0,”clientid”	Acquire MQTT client
3	AT+CMQTTCONNECT=0,”tcp://broker”,60,1	Connect to broker
4	AT+CMQTTTOPIC=0,12	Set topic length
5	sensor/data	Send topic name
6	AT+CMQTTPAYLOAD=0,20	Set payload length
7	{“temp”:25,”hum”:60}	Send JSON payload
8	AT+CMQTTPUB=0,1,60	Publish message

Advantages of MQTT vs HTTP:

• Reduced bandwidth consumption (60-70% less data)
• Persistent connections reduce latency
• Quality of Service (QoS) levels ensure delivery
• Built-in keep-alive mechanism

Project 3: GPS Asset Tracking System

Leveraging the integrated GNSS receiver, this project creates a vehicle/asset tracking solution transmitting location data to a server.

GPS Initialization Sequence:

sendData(“AT+CGPS=1”, 1000, DEBUG);  // Power on GPS

delay(30000);  // Wait for satellite acquisition

// Read GPS data

sendData(“AT+CGPSINFO”, 1000, DEBUG);

// Response: +CGPSINFO: lat,N,lon,E,date,time,alt,speed,course

Important GPS Considerations:

• Cold start acquisition: 30-45 seconds
• Warm start: 10-15 seconds
• Antenna must have clear sky view
• Active antennas require 2.85V supply (module provides this)
• Indoor GPS acquisition unreliable

Project 4: SMS Alert System for Critical Events

Despite modern alternatives, SMS remains reliable for critical alerts due to its guaranteed delivery and no internet dependency.

SMS AT Commands:

// Send SMS

sendData(“AT+CMGF=1”, 500, DEBUG);  // Text mode

sendData(“AT+CMGS=\”+1234567890\””, 500, DEBUG);

sendData(“Alert: Temperature exceeded threshold”, 500, DEBUG);

sendData(“\x1A”, 500, DEBUG);  // Ctrl+Z to send

// Read SMS

sendData(“AT+CMGF=1”, 500, DEBUG);

sendData(“AT+CMGR=1”, 500, DEBUG);  // Read message index 1

Troubleshooting Common Integration Issues

Power-Related Problems

Symptom: Module restarts randomly, NET LED stops blinking

Root Causes:

• Insufficient current capability (most common)
• Voltage drop during transmission peaks
• Poor PCB power distribution

Solutions:

• Use dedicated 5V 2A power supply
• Add 470μF low-ESR capacitor near VBAT pins
• Implement battery backup
• Monitor supply voltage with AT+CBC command

Network Registration Failures

Symptom: AT+CREG? returns 0,2 (searching) continuously

Diagnostic Steps:

1. Check signal strength: AT+CSQ (should return >10)
2. Verify SIM card: AT+CPIN? (should return READY)
3. Check antenna connection and placement
4. Verify correct frequency bands for your carrier
5. Confirm data plan is active

Signal Quality Interpretation:

RSSI Value	Signal Quality	Status
0-9	Poor	Network issues likely
10-14	Fair	Usable but unstable
15-19	Good	Reliable connection
20-31	Excellent	Optimal performance
99	Unknown	Not registered

Serial Communication Issues

Symptom: No response from module or garbled characters

Checklist:

• Verify 115200 baud rate setting
• Check TX/RX wiring (often swapped)
• Confirm level shifting circuit functionality
• Test with hardware serial (not SoftwareSerial)
• Verify PWRKEY power-on sequence (1-2 second LOW pulse)

HTTP/HTTPS Connection Failures

Symptom: AT+HTTPACTION returns error codes

Common Error Codes:

Code	Meaning	Solution
602	HTTP timeout	Increase timeout parameter
603	No HTTP session	Initialize with AT+HTTPINIT
604	DNS resolve failed	Check APN configuration
606	Socket error	Verify network registration

Useful Resources and Documentation

Official Documentation Downloads

Resource	Description	Download Link
SIM7600 AT Command Manual	Complete AT command reference	SIMCom Website
Hardware Design Guide	PCB layout and schematic reference	SIMCom Documentation Portal
SIM7600 Datasheet	Electrical and RF specifications	Available from distributors
MQTT Application Note	MQTT AT command implementation	SIM7500/7600 Series MQTT ATC

Arduino Libraries and Code Repositories

Library/Repository	Purpose	Link
TinyGSM	Primary Arduino cellular library	GitHub – vshymanskyy/TinyGSM
Waveshare Examples	Board-specific examples	Waveshare Wiki
ElementZ Sample Codes	MQTT and HTTP examples	GitHub – elementzonline
Maduino Examples	ATSAMD-based implementations	Makerfabs GitHub

Development Boards and Modules

Product	Features	Typical Use Case
Maduino Zero 4G LTE	ATSAMD21 + SIM7600, Arduino compatible	Rapid prototyping
Waveshare SIM7600 HAT	Raspberry Pi compatible shield	Linux-based applications
LilyGO T-SIM7600	ESP32 + SIM7600 integrated board	Battery-powered IoT
Generic SIM7600 Breakout	Bare module with minimal circuitry	Custom PCB integration

Carrier APN Settings Database

Correct APN configuration is critical for data connectivity:

North America:

• AT&T: “phone”
• T-Mobile: “fast.t-mobile.com”
• Verizon: “vzwinternet”

Europe:

• Vodafone: “internet”
• Orange: “orange.fr”
• O2: “mobile.o2.co.uk”

Asia-Pacific:

• Airtel (India): “airtelgprs.com”
• Telstra (Australia): “telstra.internet”
• China Mobile: “cmnet”

Note: APN settings vary by carrier and plan type. Contact your carrier for accurate settings.

Online Communities and Support

• Arduino Forum – Networking Section: Active community for GSM/LTE troubleshooting
• SIMCom Support Portal: Official technical support and firmware updates
• GitHub Issues: TinyGSM repository for library-specific questions
• Element14 Community: Hardware design discussions and PCB layout reviews

Performance Optimization Tips

Minimizing Power Consumption

For battery-powered applications, power management becomes critical:

Sleep Mode Implementation:

// Enter minimum functionality mode

sendData(“AT+CFUN=0”, 1000, DEBUG);

// Use DTR pin for wake control

digitalWrite(DTR_PIN, HIGH);  // Sleep

delay(60000);  // Sleep period

digitalWrite(DTR_PIN, LOW);   // Wake

Power Consumption Modes:

Mode	Current Draw	Wake Method
Active (transmitting)	1.5-2.0A	N/A
Idle (registered)	25mA	N/A
Sleep mode	3-5mA	DTR, incoming SMS/call
Power down	<1mA	PWRKEY pulse

Improving Data Throughput

Buffer Size Optimization:

#define TINY_GSM_RX_BUFFER 2048  // Increase for higher throughput

TCP/IP Socket Configuration:

• Use larger packet sizes (1024-1460 bytes)
• Minimize socket open/close cycles
• Implement connection pooling for multiple requests
• Consider UDP for applications tolerating packet loss

Reducing Connection Latency

Network registration and connection establishment can take significant time:

Optimization Strategies:

1. Keep connections alive: Maintain TCP/IP connection rather than reconnecting
2. Cache DNS results: Store resolved IP addresses when possible
3. Use IP addresses directly: Bypass DNS lookup entirely if practical
4. Implement fast dormancy: AT+CFDCFG for LTE power state management

Frequently Asked Questions (FAQs)

1. Can I use Arduino Uno with SIM7600 module?

Yes, but with significant limitations. Arduino Uno’s 2KB RAM restricts buffer sizes, and SoftwareSerial is required since Uno has only one hardware serial port (used by USB). Level shifting is mandatory since Uno operates at 5V. For production projects, consider upgrading to Arduino Mega, ESP32, or SAMD-based boards offering better performance and multiple hardware serial ports.

2. Why does my SIM7600 keep resetting randomly?

Random resets almost always indicate power supply issues. The SIM7600 draws up to 2A during peak transmission, which exceeds USB port capabilities (500mA). Solutions include using a dedicated 5V 2A power adapter, adding large capacitors (330-470μF) near the VBAT pins, or implementing a Li-ion battery backup. Verify stable voltage with AT+CBC command during transmission.

3. What’s the difference between SIM7600 and SIM7600-H modules?

The primary difference is LTE category performance: SIM7600 is LTE Cat-1 (10Mbps down/5Mbps up) while SIM7600-H is LTE Cat-4 (150Mbps down/50Mbps up). For most IoT applications sending small sensor data packets, Cat-1 performance suffices and costs less. Choose Cat-4 for applications requiring faster data transfer like image transmission or video streaming.

4. How do I determine the correct APN for my SIM card?

Contact your cellular carrier’s technical support or check their website for IoT/M2M APN settings. Alternatively, test the APN on a smartphone: Settings > Mobile Networks > Access Point Names. Note that consumer phone APNs may differ from IoT/M2M APNs. Some carriers require special IoT plans with static IP addresses.

5. Can TinyGSM library work with SIM7600 for HTTPS connections?

TinyGSM provides basic HTTP support through the SIM7600’s native AT commands. For HTTPS/SSL, additional implementation is needed using the SSLClient library wrapper or the module’s built-in SSL AT commands (AT+CSSLCFG, AT+SHSSL). The GitHub repository govorox/SSLClient provides Arduino compatibility for secure connections with cellular modules.

Conclusion

The SIM7600 Arduino combination delivers a robust solution for cellular IoT applications requiring 4G LTE connectivity. Successful implementation requires careful attention to power supply design, proper voltage level translation, and understanding of both hardware interfaces and software libraries. The transition from legacy 2G modules to LTE technology provides not only faster data speeds but also future-proof designs as cellular networks continue evolving.

For PCB engineers and embedded developers, the key success factors include adequate power supply provisioning, proper antenna design, correct serial communication setup, and leveraging established libraries like TinyGSM. While challenges exist around memory constraints on smaller Arduino boards and the complexity of AT command protocols, the extensive documentation and active community support make the SIM7600 an accessible choice for both prototyping and production deployments.

Whether building remote sensors, GPS trackers, environmental monitors, or industrial control systems, the SIM7600 provides the cellular connectivity backbone for reliable, long-range wireless communication in locations where traditional networking isn’t feasible.