STMicroelectronics STM8 Manual page 115

void BH1750_write(unsigned char cmd)
{
I2C_GenerateSTART(ENABLE);
while(!I2C_CheckEvent(I2C_EVENT_MASTER_MODE_SELECT));
I2C_Send7bitAddress(BH1750_addr, I2C_DIRECTION_TX);
while(!I2C_CheckEvent(I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
I2C_SendData(cmd);
while(!I2C_CheckEvent(I2C_EVENT_MASTER_BYTE_TRANSMITTED));
I2C_GenerateSTOP(ENABLE);
}
unsigned int BH1750_read_word(void)
{
unsigned long value = 0x0000;
unsigned char num_of_bytes = 0x02;
unsigned char bytes[2] = {0x00, 0x00};
while(I2C_GetFlagStatus(I2C_FLAG_BUSBUSY));
I2C_GenerateSTART(ENABLE);
while(!I2C_CheckEvent(I2C_EVENT_MASTER_MODE_SELECT));
I2C_Send7bitAddress(BH1750_addr, I2C_DIRECTION_RX);
while(!I2C_CheckEvent(I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
while(num_of_bytes)
{
if(I2C_CheckEvent(I2C_EVENT_MASTER_BYTE_RECEIVED))
{
if(num_of_bytes == 0)
{
I2C_AcknowledgeConfig(I2C_ACK_NONE);
I2C_GenerateSTOP(ENABLE);
}
bytes[(num_of_bytes - 1)] = I2C_ReceiveData();
num_of_bytes--;
}
};
value = ((bytes[1] << 8) | bytes[0]);
return value;
}
unsigned int get_lux_value(unsigned char mode, unsigned int delay_time)
{
unsigned long lux_value = 0x00;
unsigned char dly = 0x00;
unsigned char s = 0x08;
while(s)
{
BH1750_write(power_up);
BH1750_write(mode);
lux_value += BH1750_read_word();
for(dly = 0; dly < delay_time; dly += 1)
{
delay_ms(1);
}