How to Use sx1509-breakout: Examples, Pinouts, and Specs

The SX1509 Breakout is a convenient solution for expanding the number of input/output (I/O) pins available on a microcontroller. Based on the Semtech SX1509 chip, this breakout board allows users to add 16 additional I/O pins through a simple I2C interface, which requires only two pins on the microcontroller. This component is particularly useful in projects where there is a need to control a large number of LEDs, buttons, or other digital devices, and it is commonly used with platforms like Arduino, Raspberry Pi, and others.

• LED matrix control
• Keypad input reading
• Additional GPIOs for microcontrollers
• Home automation
• Robotics

• Voltage: 1.2V to 3.6V
• I2C Interface: 400kHz max
• Output Current: Up to 15mA per channel
• Internal Resistor: Pull-up and pull-down
• PWM Outputs: 16 (8-bit resolution)
• Input Debouncing
• Interrupt Output

1. Powering the SX1509: Connect the VCC pin to a power supply within the range of 1.2V to 3.6V and the GND pin to the ground.

2. Connecting to a Microcontroller:

   • Connect the SDA pin to the I2C data line on your microcontroller.
   • Connect the SCL pin to the I2C clock line on your microcontroller.
   • If interrupt functionality is required, connect the INT pin to an interrupt-capable GPIO on your microcontroller.

3. Address Selection: The SX1509 supports multiple I2C addresses. Set the address by connecting the ADDR pins according to the datasheet.

4. Initialization: Initialize the SX1509 in your microcontroller's setup routine.

5. Configuration: Configure the I/O pins as either inputs or outputs depending on your application.

• Ensure that the power supply voltage does not exceed the maximum rating of 3.6V.
• Use pull-up resistors on the I2C lines if your microcontroller does not have them built-in.
• Avoid drawing more than 15mA from any single I/O pin.
• When using the interrupt feature, ensure that your microcontroller's interrupt pin is configured correctly.

#include <Wire.h>
#include <SparkFunSX1509.h> // Include SX1509 library

// Create an SX1509 object
SX1509 io;

void setup() {
  Wire.begin(); // Start I2C
  if (!io.begin(0x3E)) { // Start SX1509 at I2C address 0x3E
    Serial.println("SX1509 not found. Please check wiring.");
    while (1);
  }

  // Configure pin 7 as an output
  io.pinMode(7, OUTPUT);
}

void loop() {
  // Blink LED on pin 7
  io.digitalWrite(7, HIGH); // Turn on LED
  delay(500);
  io.digitalWrite(7, LOW); // Turn off LED
  delay(500);
}

• I2C Communication Failure: Ensure that the SDA and SCL lines are connected properly and that there are pull-up resistors if needed.
• Insufficient Power Supply: Verify that the power supply is within the specified voltage range and can provide enough current.
• Non-Responsive I/O Pins: Check if the pins are configured correctly in your code as inputs or outputs.

• Use I2C scanner code to confirm that the SX1509 is detected on the I2C bus.
• Check for soldering issues on the breakout board.
• Ensure that the interrupt pin is not floating if used.

Q: Can I use the SX1509 with a 5V microcontroller? A: Yes, but ensure that the SX1509's VCC is connected to a voltage within its range (1.2V to 3.6V), and use level shifters for the I2C lines if necessary.

Q: How many SX1509 boards can I chain together? A: You can chain multiple boards by setting unique I2C addresses for each SX1509 using the ADDR pins.

Q: Is it possible to use the PWM functionality on all pins? A: Yes, all 16 I/O pins of the SX1509 support 8-bit PWM output.