I²C Master Bus

Typedefs
typedef float	i2c_freq_t
	Type for I²C clock frequency in Hz.
typedef uint8_t	i2c_sda_t
	Type for I²C SDA pin number.
typedef uint8_t	i2c_scl_t
	Type for I²C SCL pin number.

Functions
i2c_bus_handle_t	i2c_master_bus_init (i2c_port_t p, i2c_sda_t d, i2c_scl_t c, i2c_freq_t f)
	Initialize an I²C master bus.
esp_err_t	i2c_master_bus_scan (i2c_bus_handle_t bus)
	Scan for devices on the given I²C bus.
void	i2c_master_bus_deinit (i2c_bus_handle_t bus)
	Deinitialize the I²C master bus.

I²C Master Default Pins and Settings
#define	I2C_MASTER_SCL_IO   (8)
	GPIO number for I²C SCL.
#define	I2C_MASTER_SDA_IO   (7)
	GPIO number for I²C SDA.
#define	I2C_MASTER_NUM   I2C_NUM_0
	I²C port number.
#define	I2C_MASTER_FREQ_HZ   (100000)
	I²C clock frequency in Hz.

Detailed Description

Copyright

Copyright (c) 2026 Adrien Chevrier. Under AGPL-3.0-or-later license.

ESP-IDF wrapper for default I²C master bus management.

Uses the new ESP-IDF I²C interface.

Macro Definition Documentation

I2C_MASTER_FREQ_HZ

#define I2C_MASTER_FREQ_HZ   (100000)

I²C clock frequency in Hz.

I2C_MASTER_NUM

#define I2C_MASTER_NUM   I2C_NUM_0

I²C port number.

I2C_MASTER_SCL_IO

#define I2C_MASTER_SCL_IO   (8)

GPIO number for I²C SCL.

I2C_MASTER_SDA_IO

#define I2C_MASTER_SDA_IO   (7)

GPIO number for I²C SDA.

Typedef Documentation

i2c_freq_t

typedef float i2c_freq_t

Type for I²C clock frequency in Hz.

i2c_scl_t

typedef uint8_t i2c_scl_t

Type for I²C SCL pin number.

i2c_sda_t

typedef uint8_t i2c_sda_t

Type for I²C SDA pin number.

Function Documentation

i2c_master_bus_deinit()

void i2c_master_bus_deinit

(

i2c_bus_handle_t

bus

)

Deinitialize the I²C master bus.

Releases resources and frees memory associated with the bus handle.

Parameters

[in,out]

bus

Handle to the I²C bus to deinitialize.

Warning

This function must run inside a critical section.

i2c_master_bus_init()

i2c_bus_handle_t i2c_master_bus_init	(	i2c_port_t	p,
		i2c_sda_t	d,
		i2c_scl_t	c,
		i2c_freq_t	f )

Initialize an I²C master bus.

Configures the I²C controller with the given pins, port, and clock frequency.

Parameters

[in]	p	I²C port number.
[in]	d	SDA pin number.
[in]	c	SCL pin number.
[in]	f	Clock frequency.

Return values

i2c_bus_handle_t	Handle to the initialized I²C bus.
NULL	On failure.

Note

Must call i2c_master_bus_deinit() to free resources later.

Warning

This function must run inside a critical section.

i2c_master_bus_scan()

esp_err_t i2c_master_bus_scan

(

i2c_bus_handle_t

bus

)

Scan for devices on the given I²C bus.

Logs detected device addresses.

Parameters

[in]

bus

Handle to the I²C bus.

Return values

ESP_OK	On success.
ESP_ERR_INVALID_ARG	If any parameter is NULL.