Driver interface for the BH1750 ambient light sensor. More...

#include "stdint.h"
#include "stddef.h"

Data Structures
struct	BH1750_HandleTypeDef
	BH1750 driver handle. More...

Macros
#define	BH1750_ADDRESS_GND (0x23 << 1)
#define	BH1750_ADDRESS_VCC (0x5C << 1)
#define	BH1750_ADDRESS BH1750_ADDRESS_GND
#define	BH1750_CONTINIOUS_H_RES_MODE 0x10
#define	BH1750_CONTINIOUS_H_RES_MODE2 0x11
#define	BH1750_CONTINIOUS_L_RES_MODE 0x13
#define	BH1750_ONE_TIME_H_RES_MODE 0x20
#define	BH1750_ONE_TIME_H_RES_MODE2 0x21
#define	BH1750_ONE_TIME_L_RES_MODE 0x23
#define	BH1750_PWR_DOWN 0x00
#define	BH1750_PWR_ON 0x01
#define	BH1750_RST 0x07
#define	MEASUREMENT_TIME_H_RES_MODE 120
#define	MEASUREMENT_TIME_H_RES_MODE2 120
#define	MEASUREMENT_TIME_L_RES_MODE 16
#define	BH1750_LUX_COEFF 1.2f
	Lux conversion coefficient: raw / BH1750_LUX_COEFF = lux.

Typedefs
typedef int8_t(*	BH1750_I2C_Read_Func) (uint8_t dev_addr, uint8_t reg_addr, uint8_t *data, uint16_t len)
	Function pointer type for platform I2C read.
typedef int8_t(*	BH1750_I2C_Write_Func) (uint8_t dev_addr, uint8_t reg_addr, uint8_t *data, uint16_t len)
	Function pointer type for platform I2C write.
typedef void(*	BH1750_Delay_Func) (uint32_t ms)
	Function pointer type for platform millisecond delay.

Functions
int8_t	BH1750_Init (BH1750_HandleTypeDef *dev)
	Powers on the BH1750 and sends the initial measurement mode command.
int8_t	BH1750_Read (BH1750_HandleTypeDef *dev)
	Reads the latest illuminance measurement from the BH1750.

Detailed Description

Driver interface for the BH1750 ambient light sensor.

The BH1750 is a 16-bit I2C ambient light sensor with a configurable measurement mode. This driver supports all six modes defined in the datasheet and is platform-independent through injected function pointers.

Typical usage:

BH1750_HandleTypeDef hbh1750;
hbh1750.address   = BH1750_ADDRESS_GND;
hbh1750.mode      = BH1750_ONE_TIME_H_RES_MODE;
hbh1750.i2c_read  = my_i2c_read;
hbh1750.i2c_write = my_i2c_write;
hbh1750.delay_ms  = my_delay;
BH1750_Init(&hbh1750);
 
BH1750_Read(&hbh1750);
float lux = hbh1750.lux;

Author: Şule Nur Demirdaş

Date: April 2026

Macro Definition Documentation

◆ BH1750_ADDRESS

#define BH1750_ADDRESS BH1750_ADDRESS_GND

Default address alias.

◆ BH1750_ADDRESS_GND

#define BH1750_ADDRESS_GND (0x23 << 1)

I2C address when ADDR pin = GND.

◆ BH1750_ADDRESS_VCC

#define BH1750_ADDRESS_VCC (0x5C << 1)

I2C address when ADDR pin = VCC.

◆ BH1750_CONTINIOUS_H_RES_MODE

#define BH1750_CONTINIOUS_H_RES_MODE 0x10

Continuous high-res mode (1 lx, ~120 ms).

◆ BH1750_CONTINIOUS_H_RES_MODE2

#define BH1750_CONTINIOUS_H_RES_MODE2 0x11

Continuous high-res mode2 (0.5 lx, ~120 ms).

◆ BH1750_CONTINIOUS_L_RES_MODE

#define BH1750_CONTINIOUS_L_RES_MODE 0x13

Continuous low-res mode (4 lx, ~16 ms).

◆ BH1750_ONE_TIME_H_RES_MODE

#define BH1750_ONE_TIME_H_RES_MODE 0x20

One-time high-res mode (1 lx, ~120 ms).

◆ BH1750_ONE_TIME_H_RES_MODE2

#define BH1750_ONE_TIME_H_RES_MODE2 0x21

One-time high-res mode2 (0.5 lx, ~120 ms).

◆ BH1750_ONE_TIME_L_RES_MODE

#define BH1750_ONE_TIME_L_RES_MODE 0x23

One-time low-res mode (4 lx, ~16 ms).

◆ BH1750_PWR_DOWN

#define BH1750_PWR_DOWN 0x00

Power-down command.

◆ BH1750_PWR_ON

#define BH1750_PWR_ON 0x01

Power-on command.

◆ BH1750_RST

#define BH1750_RST 0x07

Reset data register command.

◆ MEASUREMENT_TIME_H_RES_MODE

#define MEASUREMENT_TIME_H_RES_MODE 120

Typical conversion time for H-res modes.

◆ MEASUREMENT_TIME_H_RES_MODE2

#define MEASUREMENT_TIME_H_RES_MODE2 120

Typical conversion time for H-res2 mode.

◆ MEASUREMENT_TIME_L_RES_MODE

#define MEASUREMENT_TIME_L_RES_MODE 16

Typical conversion time for L-res mode.

Function Documentation

◆ BH1750_Init()

int8_t BH1750_Init ( BH1750_HandleTypeDef * dev )

Powers on the BH1750 and sends the initial measurement mode command.

Parameters

[in,out] dev Pointer to a BH1750_HandleTypeDef with all fields set.

Returns: 0 on success.; -1 if a required function pointer is NULL.; -2 if an I2C write fails.

◆ BH1750_Read()

int8_t BH1750_Read ( BH1750_HandleTypeDef * dev )

Reads the latest illuminance measurement from the BH1750.

For one-time modes the function re-sends the mode command and waits for conversion before reading. For continuous modes it reads immediately. The result is stored in dev->lux.