LILYGO Sim Shield Expansion Board User Guide

Version History:

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Table of Contents

• Overview
• Electrical Parameters
• Mainboard Compatibility Configuration
• Interface Description
• Usage Examples
• Schematics & Resources

Overview

The Sim Shield is a multifunction expansion board specifically designed for the LilyGo T-Sim Series, integrating the following features:

1. Triple-Channel Current Sensing: Based on the INA3221 chip, supports independent current monitoring.
2. LoRa Wireless Communication: Integrated SX1262 module, supports long-range transmission.
3. Wide Voltage DC Input: Supports 7~36V DC input with built-in voltage regulation circuitry.
4. RS485 Interface: Hardware auto direction control (ADCDC), supports industrial communication.
5. I2C/SPI Expansion: Provides standard interfaces for connecting peripherals.

⚠️ Important Warning:
Always check jumper cap and DIP switch settings before powering on. Incorrect configuration may cause hardware damage.

Electrical Parameters

Mainboard Compatibility Configuration

1. SIM7000G / A7670X / A7608X (ESP32 Version)

Applicable Models:

• SIM7000G-ESP32
• A7608X-ESP32
• A7670X-ESP32

Note: For A7670X/A7608X, a resistor needs to be removed to use the Sim Shield. See this link for details.

Pin Mapping:

2. SIM7600X (ESP32 Version)

Applicable Models:

• SIM7600X-ESP32

Pin Mapping (Special Notes):

Note: These three GPIOs are occupied by the Sim Shield. Do not use them for other purposes.

3. SIM7670G (ESP32-S3 Version)

Applicable Models:

• SIM7670G-ESP32S3

Pin Mapping:

4. A7608X (ESP32-S3 Version)

Applicable Models:

• A7608X-ESP32S3

Pin Mapping:

5. SIM7080G (ESP32-S3 PMU Version)

Important Notes:

1. SIM7080G does not expose external battery pins. The 18650 battery holder positive terminal needs to be soldered to a designated position.
2. The 18650 battery holder on the mainboard must be removed (conflicts with Sim Shield).
3. The DC5 and VSYS pins must be left unconnected.
4. Additional wires need to be soldered to support 5V input (see diagram below).

Applicable Models:

• SIM7080G-ESP32S3

Pin Mapping:

6. Standard Series (SIM7000G/A7670X/SIM7670G/SIM7080G)

Pin Mapping (General):

Interface Description

1. Battery Connection

• Connect the external battery interface to the mainboard battery interface via a jumper cap.
• Note: If using an external battery, do NOT install a battery in the mainboard's 18650 socket.

2. Current Monitoring Setup

• Vertical Jumper Cap: Routes battery current to INA3221 Channel 2, enabling charge/discharge current monitoring.
• No Jumper Cap: Monitors the screw terminal interface current.
• Note: When using battery monitoring, do NOT connect the screw terminals.

3. 5V Power Interface

• 2.00mm 2Pin JST interface for external power supply.
• Can also be connected directly to the mainboard solar port for charging (requires disconnecting J21 jumper).
• This interface is recommended for primary power due to lower voltage drop.

4. SD Card Interface

• The Sim Shield remaps the SPI interface.
• After using the Sim Shield, the SD card must be inserted into the expansion board, NOT the mainboard.

5. RS485 Interface

• Hardware auto direction control (ADCDC).
• Recommended communication baud rate ≤115200.

6. I2C Interface

• Supports standard 0.96-inch OLED displays.
• Note on Pin Order: Ensure the OLED interface pinout is correct.

7. SPI Interface

• Exposes the SPI bus for the SD card and LoRa module.

8. Current Sensing Channels

Terminal Definitions:

• IN+: Current flow direction into the sensor.
• G: Load GND.
• IN-: Current flow direction out of the sensor.

Usage Examples

Schematics & Resources

• Schematic: T-SimShield-Rev1.0.pdf
• Solar Panel Specifications: 3D5ETR00372_233153V01_20250828.pdf
• Compatibility List: Supports all LilyGo T-Sim series mainboards.

Summary of Important Notes

1. Always check jumper and DIP switch settings before powering on.
2. Do NOT install a battery in the mainboard's 18650 socket when using an external battery.
3. The SD card must be inserted into the expansion board, NOT the mainboard.
4. Pin mappings differ between mainboard models. Configure according to the corresponding table.
5. Recommended RS485 baud rate is ≤115200.