SIMCOM A7680C LTE Cat1 Module Development Board

1. Product Overview

The SIMCOM A7680C is an ultra-small, ultra-thin LTE Cat 1 module designed for the Chinese market. It supports LTE-TDD/LTE-FDD wireless communication standards, offering a maximum downlink rate of 10Mbps and a maximum uplink rate of 5Mbps. This module is compatible with SIMCom's classic 2G products (SIM800C, SIM868, etc.), facilitating a smooth transition to LTE products for compact and feature-rich terminal designs.

The A7680C integrates multiple network protocols and supports mainstream software operating system drivers (USB drivers for Windows, Linux, and Android). It features powerful expansion capabilities through industry-standard interfaces like UART and GPIO, making it suitable for various IoT applications such as vehicle communication terminals, security terminals, POS systems, industrial routers, and telemedicine devices.

2. Setup Guide

2.1. Physical Connections

1. SIM Card Insertion: Locate the SIM card slot on the board (refer to Figure 1). Gently insert a 1.8V or 3V (U)SIM card into the slot until it clicks into place. Ensure correct orientation.
2. Antenna Connection: Connect the appropriate antennas to the GSM ANTA and GPS ANTA connectors on the board. For optimal performance, ensure antennas are securely attached.
3. Power Supply: Connect a power source within the supported voltage range of 3.4V to 4.2V (typical 3.8V) to the designated power pins. Refer to the pinout diagram (Figure 3) for exact power connections.
4. USB Connection: For data communication and power, connect the Micro USB port on the board to your computer or host device using a compatible USB cable.
5. UART/Serial Connection: If using serial communication, connect your host device to the UART pins as indicated in the pinout diagram (Figure 3).

2.2. Driver Installation

Before operating the module, ensure the necessary USB drivers are installed on your host system. The A7680C supports USB drivers for:

• Microsoft Windows 7/8/10
• Linux
• Android (RIL support for Android 5.0/6.0/7.0/8.0/9.0)

Drivers are typically provided by the module manufacturer or can be found on their official support website.

3. Operating Instructions

3.1. AT Command Operation

The A7680C module is primarily controlled via AT commands sent through the serial port (UART) or USB virtual serial port. Refer to the official SIMCOM A7680C AT Command Set documentation for a comprehensive list of commands and their usage.

3.2. Data Transmission

The module supports LTE Cat 1 data transmission with:

• Upstream: Maximum 5Mbps
• Downlink: Up to 10Mbps

It supports various network protocols including TCP/IP/IPV4/IPV6/MultiPDP/FTP/HTTP/DNS, RNDIS/ECM/PPP, and TLS.

3.3. Software Functions

The A7680C offers a range of software functionalities:

• Remote Upgrade (FOTA): Supports Firmware Over-The-Air updates for convenient software maintenance.
• Base Station Positioning (LBS): Provides location information based on cellular network data.
• SSL Protocol: Ensures secure communication.
• TTS Support: Text-to-Speech functionality.
• MQTT Support: For lightweight messaging protocol in IoT applications.
• WIFI Scan: Ability to scan for Wi-Fi networks (note: this is a cellular module, Wi-Fi scan functionality may be for specific use cases or integrated features).

4. Maintenance

To ensure the longevity and optimal performance of your A7680C module, follow these maintenance guidelines:

• Software Updates: Regularly check for and apply firmware updates using the USB port software upgrade or FOTA (Firmware Over-The-Air) remote software upgrade feature. This ensures you have the latest features and bug fixes.
• Environmental Conditions: Operate the module within its specified working temperature range of -40℃ to +85℃. Avoid exposure to extreme temperatures, high humidity, dust, or corrosive environments.
• Cleaning: Keep the module clean and free from dust. Use a soft, dry cloth for cleaning. Do not use liquid cleaners or solvents.
• Physical Inspection: Periodically inspect the board for any signs of physical damage, loose connections, or corrosion.

5. Troubleshooting

If you encounter issues with your A7680C module, consider the following troubleshooting steps:

• No Power: Verify that the power supply is connected correctly and provides the specified voltage (3.4V ~ 4.2V). Check power indicator LEDs on the board, if available.
• Module Not Detected by Host: Ensure USB drivers are correctly installed. Try a different USB port or cable. For serial connections, verify UART wiring and baud rate settings.
• No Network Connection: Check if the SIM card is inserted correctly and is active. Ensure antennas are properly connected. Verify network coverage in your area. Use AT commands to query network registration status (e.g., AT+CREG?).
• AT Command Issues: Confirm that the serial port settings (baud rate, data bits, parity, stop bits) match the module's requirements. Ensure the AT command syntax is correct according to the official documentation.
• Software Functionality Problems: Ensure the module firmware is up to date. Check for any specific error codes returned by AT commands related to the function (e.g., LBS, MQTT).

For advanced troubleshooting, consult the SIMCOM A7680C documentation or contact technical support.

6. Specifications

6.1. General Characteristics

• Model Number: A7680C Board
• Origin: Mainland China
• Frequency Bands:
  • LTE-TDD: B34/B38/B39/B40/B41
  • LTE-FDD: B1/B3/B5/B8
• Supported Voltage Range: 3.4V ~ 4.2V (typical: 3.8V)
• Working Temperature: -40℃ ~ +85℃
• Dimensions: 15.7mm x 17.6mm x 2.1mm (Module only)
• Weight: TBD
• Control Interface: AT command operation

6.2. Data Transmission

• LTE Cat 1 Upstream: Max 5Mbps
• LTE Cat 1 Downlink: Up to 10Mbps

6.3. Software Features

• OS Driver Support: Microsoft Windows 7/8/10, Linux, Android
• Android RIL Support: Android 5.0/6.0/7.0/8.0/9.0
• Software Upgrade: USB port software upgrade, FOTA remote software upgrade
• Network Protocols: TCP/IP/IPV4/IPV6/MultiPDP/FTP/HTTP/DNS, RNDIS/ECM/PPP, TLS
• Additional Features: LBS (Location-Based Services), TTS (Text-to-Speech), MQTT, WIFI Scan

6.4. Hardware Interfaces

• USB2.0
• Serial Port (UART)
• (U)SIM Card (1.8V/3V)
• Analog Audio
• ADC (Analog-to-Digital Converter)
• GPIO (General Purpose Input/Output)
• Antenna Interfaces: Main Set (GSM ANTA, GPS ANTA, BT ANTA)

6.5. Certifications

• 3C#/SRRC#/NAL#
• RoHS#/REACH#

7. User Tips

• Compatibility Check: Always verify the module's frequency bands (LTE-TDD B34/B38/B39/B40/B41, LTE-FDD B1/B3/B5/B8) are compatible with your regional cellular network before deployment.
• Stable Power Supply: Ensure a stable power supply within the recommended voltage range (3.4V-4.2V) to prevent unexpected behavior or damage to the module. Fluctuations can lead to connectivity issues.
• Antenna Quality: Use high-quality, impedance-matched antennas for both GSM and GPS to maximize signal reception and transmission efficiency.
• AT Command Reference: Keep the official SIMCOM A7680C AT Command Set documentation handy for quick reference during development and debugging.

8. Warranty and Support

8.1. Limited Warranty

This product comes with a 12-month Manufacturer's Limited Warranty. This warranty covers defective items but excludes items damaged and/or misused after receipt. Please retain your proof of purchase for warranty claims.

8.2. Technical Support

For technical assistance, detailed documentation, or specific inquiries regarding the SIMCOM A7680C module, please refer to the official SIMCOM website or contact the seller/manufacturer directly. Provide your product model and a detailed description of the issue for efficient support.