IS3750 STM32 Traffic Light Example

This example demonstrates how to use the IS3750 Addressable LED Controller Chip with an STM32 microcontroller.
The project is based on STM32CubeIDE and uses the HAL drivers from ST's Cube firmware library.

✅ The example was tested using the Nucleo-C071 evaluation board, but it can be adapted to any STM32 microcontroller using HAL.

📦 The .rar file in this repository contains the full STM32CubeIDE project.

🛒 Buy the IS4310 – Modbus RTU Slave Chip

For more information or to purchase the IS4310, visit:
👉 www.inacks.com/is4310

You can also get the evaluation board for the IS3750, compatible with Arduino and Nucleo boards:
👉 Kappa3750Ard – Available at www.inacks.com/kappa4310ard

For more products and documentation, visit:
👉 www.inacks.com

📄 Example Code

Below is a simplified version of the example excluding the auto-generated HAL files, for quick reference.

#define IS3750_REGISTER_SHOW        0x00
#define IS3750_REGISTER_LED1_RED    0x01
#define IS3750_REGISTER_LED1_GREEN  0x02
#define IS3750_REGISTER_LED1_BLUE   0x03
#define IS3750_REGISTER_LED2_RED    0x04
#define IS3750_REGISTER_LED2_GREEN  0x05
#define IS3750_REGISTER_LED2_BLUE   0x06
#define IS3750_REGISTER_LED3_RED    0x07
#define IS3750_REGISTER_LED3_GREEN  0x08
#define IS3750_REGISTER_LED3_BLUE   0x09


// Sends brightness value to a specific register of the IS3750.
void writeLedRegister(uint16_t registerAddress, uint8_t bright) {
  uint8_t IS3750_I2C_Chip_Address = 0x12 << 1; // STM32 HAL expects 8-bit I2C address
  HAL_I2C_Mem_Write(&hi2c1, IS3750_I2C_Chip_Address, registerAddress, I2C_MEMADD_SIZE_16BIT, &bright, 1, 1000);
}

// Triggers the IS3750 to update the LED outputs.
void showLEDs(void) {
  uint8_t IS3750_I2C_Chip_Address = 0x12 << 1;
  uint8_t dataToWrite[1] = {1}; // Command to show updated values
  HAL_I2C_Mem_Write(&hi2c1, IS3750_I2C_Chip_Address, IS3750_REGISTER_SHOW, I2C_MEMADD_SIZE_16BIT, dataToWrite, 1, 1000);
}

// Sets all LED registers to 0 (turns off all LEDs).
void clearAllLedRegisters(void) {
  uint8_t IS3750_I2C_Chip_Address = 0x12 << 1;
  uint8_t dataToWrite[1200 * 3] = {0}; // 3600 zeroed bytes
  HAL_I2C_Mem_Write(&hi2c1, IS3750_I2C_Chip_Address, IS3750_REGISTER_LED1_RED, I2C_MEMADD_SIZE_16BIT, dataToWrite, sizeof(dataToWrite), 1000);
}


int main(void)
{
  while (1)
  {
    // Show green on LED1
    clearAllLedRegisters();
    writeLedRegister(IS3750_REGISTER_LED1_GREEN, 5);
    showLEDs();
    HAL_Delay(500);

    // Show yellow on LED2 (Red + Green)
    clearAllLedRegisters();
    writeLedRegister(IS3750_REGISTER_LED2_RED, 5);
    writeLedRegister(IS3750_REGISTER_LED2_GREEN, 5);
    showLEDs();
    HAL_Delay(500);

    // Show blue on LED3
    clearAllLedRegisters();
    writeLedRegister(IS3750_REGISTER_LED3_BLUE, 5);
    showLEDs();
    HAL_Delay(500);
  }
}