How to Use ILI: Examples, Pinouts, and Specs

The ILI (Inter-Integrated Circuit) is a communication protocol designed for connecting low-speed devices such as sensors, microcontrollers, and other peripherals in a circuit. It enables efficient data transfer between devices using a simple two-wire interface, consisting of a data line (SDA) and a clock line (SCL). ILI is widely used in embedded systems due to its simplicity, scalability, and ability to support multiple devices on the same bus.

• Communication between microcontrollers and sensors (e.g., temperature, pressure, or light sensors)
• Interfacing with EEPROMs, ADCs, and DACs
• Connecting real-time clocks (RTC) to microcontrollers
• Driving small displays or other peripherals
• Multi-device communication in embedded systems

• Protocol Type: Serial, synchronous
• Number of Wires: 2 (SDA - Serial Data, SCL - Serial Clock)
• Data Transfer Rate: Standard mode (100 kHz), Fast mode (400 kHz), Fast mode plus (1 MHz), High-speed mode (3.4 MHz)
• Addressing: 7-bit or 10-bit addressing
• Maximum Devices: Up to 127 devices (7-bit addressing)
• Voltage Levels: Typically 3.3V or 5V (depending on the system)
• Pull-up Resistors: Required on both SDA and SCL lines

The ILI protocol does not refer to a specific physical component but rather a communication standard. However, devices using ILI typically have the following pin configuration:

1. Connect the SDA and SCL Lines:

   • Connect the SDA and SCL pins of all devices to the corresponding lines on the ILI bus.
   • Use pull-up resistors (typically 4.7 kΩ or 10 kΩ) on both SDA and SCL lines to ensure proper signal levels.

2. Power the Devices:

   • Connect the VCC and GND pins of all devices to the appropriate power supply and ground.

3. Assign Unique Addresses:

   • Ensure each device on the ILI bus has a unique address. This is typically set by hardware (e.g., address pins) or software.

4. Write Code for Communication:

   • Use a microcontroller or processor to send and receive data over the ILI bus. Libraries like Wire.h (for Arduino) simplify this process.

• Pull-up Resistors: Always include pull-up resistors on the SDA and SCL lines. Without them, the bus will not function correctly.
• Bus Length: Keep the bus length as short as possible to minimize signal degradation and interference.
• Clock Speed: Ensure all devices on the bus support the selected clock speed.
• Address Conflicts: Avoid address conflicts by verifying the unique address of each device.

Below is an example of how to use the ILI protocol to communicate with a sensor using an Arduino UNO:

#include <Wire.h> // Include the Wire library for ILI communication

#define SENSOR_ADDRESS 0x40 // Replace with the ILI address of your sensor

void setup() {
  Wire.begin(); // Initialize the ILI bus
  Serial.begin(9600); // Start serial communication for debugging
}

void loop() {
  Wire.beginTransmission(SENSOR_ADDRESS); // Start communication with the sensor
  Wire.write(0x00); // Send a command or register address (example: 0x00)
  Wire.endTransmission(); // End the transmission

  Wire.requestFrom(SENSOR_ADDRESS, 2); // Request 2 bytes of data from the sensor
  if (Wire.available() == 2) { // Check if 2 bytes are available
    int data = Wire.read() << 8 | Wire.read(); // Read and combine the 2 bytes
    Serial.println(data); // Print the received data to the serial monitor
  }

  delay(1000); // Wait for 1 second before the next communication
}

1. No Communication on the Bus:

   • Cause: Missing or incorrect pull-up resistors.
   • Solution: Ensure pull-up resistors are connected to both SDA and SCL lines.

2. Address Conflicts:

   • Cause: Two devices on the bus have the same address.
   • Solution: Check the datasheets of the devices and configure unique addresses.

3. Data Corruption:

   • Cause: Excessive bus length or noise.
   • Solution: Shorten the bus length and use shielded cables if necessary.

4. Device Not Responding:

   • Cause: Incorrect wiring or power supply issues.
   • Solution: Double-check all connections and ensure proper power supply.

• Q: Can I connect devices with different voltage levels on the same ILI bus?
  A: Yes, but you will need a level shifter to safely interface devices with different voltage levels.

• Q: What happens if I forget to add pull-up resistors?
  A: The ILI bus will not function correctly, as the lines will not return to a high state.

• Q: How many devices can I connect to the ILI bus?
  A: Up to 127 devices can be connected using 7-bit addressing, but practical limits depend on bus capacitance and signal integrity.

• Q: Can I use ILI for long-distance communication?
  A: ILI is not designed for long distances. For longer distances, consider using protocols like RS-485 or CAN.

This documentation provides a comprehensive guide to understanding and using the ILI protocol in your projects.