STM32 Code Example

This example (ISXMPL3750ex2) demonstrates how to use the IS3750 Addressable LED Controller chip with a STM32 microcontroller using the HAL I2C functions.

For clarity and brevity, all extra HAL definitions have been removed, leaving only the code related with the IS3750.

You can find the complete example at: www.inacks.com/isxmpl3750ex2

You can get the IS3750 evaluation board (Kappa3750Ard) compatible with STM32 Nucleo boards at: www.inacks.com/kappa3750ard

#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);
  }
}