How to Use Adafruit 4-channel I2C-safe Bi-directional Logic Level Converter: Examples, Pinouts, and Specs

The Adafruit 4-Channel I2C-Safe Bi-directional Logic Level Converter is a small device that safely steps down 5V signals to 3.3V and steps up 3.3V to 5V simultaneously. This level converter is specifically designed to interface with I2C, a popular communication protocol, which makes it ideal for connecting a 3.3V device to a 5V system without any worry of damage. Common applications include interfacing 5V microcontrollers with 3.3V sensors, or vice versa.

• Voltage Levels: 3.3V to 5V and 5V to 3.3V
• Channels: 4 bidirectional channels
• Baud Rate: Supports I2C standard mode (100 kbps) and fast mode (400 kbps)
• Dimensions: 0.63" x 0.52" x 0.1" (16mm x 13mm x 2.54mm)

1. Power Connections:

   • Connect the HV pin to the higher voltage level (e.g., 5V).
   • Connect the LV pin to the lower voltage level (e.g., 3.3V).
   • Connect the GND pin to the common ground of both systems.

2. Signal Connections:

   • Connect the high voltage (5V) logic signals to HV1 to HV4.
   • Connect the corresponding low voltage (3.3V) logic signals to LV1 to LV4.

3. I2C Communication:

   • For I2C communication, connect SDA and SCL lines from the 5V system to the HV side channels.
   • Connect the corresponding SDA and SCL lines from the 3.3V system to the LV side channels.

• Ensure that the power supply is stable and within the specified voltage range.
• Do not exceed the maximum baud rate supported by the converter.
• Avoid running high-speed signals through the level converter as it may not perform well with frequencies higher than I2C fast mode.
• Always connect the ground pin first before making any other connections to prevent potential damage.

#include <Wire.h>

void setup() {
  Wire.begin(); // join i2c bus
  Serial.begin(9600); // start serial for output
}

void loop() {
  Wire.requestFrom(0x3C, 6); // request 6 bytes from slave device #0x3C

  while (Wire.available()) { // slave may send less than requested
    char c = Wire.read(); // receive a byte as character
    Serial.print(c); // print the character
  }

  delay(500);
}

• No Signal Conversion:

  • Check if the power supply is connected correctly and the ground is common to both systems.
  • Ensure that the pins are not swapped between the HV and LV sides.

• Device Not Recognized:

  • Verify that the I2C address is correct and the device is properly connected to the SDA and SCL lines.

• If you encounter issues with I2C communication, use pull-up resistors on the SDA and SCL lines appropriate for the voltage level you are working with.
• Use a multimeter to check the continuity and voltage levels on the HV and LV sides to ensure proper operation.
• If the logic level converter is not functioning, it may be damaged due to a voltage spike or incorrect connection. Replace the component if necessary.

Q: Can this converter be used with SPI or UART? A: While it is designed for I2C, it may work with other protocols like SPI or UART at low speeds. However, it is not guaranteed and should be tested thoroughly.

Q: Is this converter bidirectional on all channels? A: Yes, all four channels are bidirectional and can be used for voltage stepping in both directions.

Q: What is the maximum current this converter can handle? A: The converter is designed for low-power signals and is not intended for high current applications. It is recommended to keep the current below 10mA per channel.