erdetn / vi2c

A tiny I2C library written in V

vi2c

vi2c is a tiny I2C communication library written in V.

Documentation

struct I2CDevice

Represents an I2C device. Fields:

• m_fd (int): File descriptor (-1 if not open).
• m_name (string): Name of the device.
• m_device_address (u8): I2C device address.
• m_device_filename (string): File path of the I2C device.
• m_is_connected (bool): Indicates if the device is connected.
• m_is_forced (bool): Indicates if the connection was forced.
• m_is_10bit (bool): true if 10 bit address, otherwise 7 bit address.

Functions

Function new(filename string, address u8, name string, is_10bit bool) I2CDevice

Creates a new I2CDevice instance.

• filename (string): File path of the I2C device.
• address (u8): I2C device address.
• name (string): Name of the device.
• is_10bit (bool): true if 10 bit address, otherwise 7 bit address.

---

Function connect(force_connection bool) bool

Connects to the I2C device.

• force_connection (bool): Indicates if the connection should be forced. Force (or not) using this slave address, even if it is already in use by a driver.

Returns true if the connection is successful, otherwise false.

---

Function read_data(max_length int) (int, []u8)

Reads data from the I2C device.

• max_length (int): Maximum length of data to read.

Returns the number of bytes read and the data as a byte slice.

---

Function write_data(data []u8) u32

Writes data to the I2C device.

• data ([]u8): Data to write.

Returns the number of bytes written.

---

Function read_data_from_reg(reg u8, max_length int) (int, []u8)

Reads data from a register of the I2C device.

• reg (u8): Register address to read from.
• max_length (int): Maximum length of data to read.

Returns the number of bytes read and the data as a byte slice.

---

Function read_reg(reg u8) (int, []u8)

Reads a register from the I2C device.

• reg (u8): Register address to read.

Returns the value read from the register as a byte slice.

---

Function write_reg_data(reg u8, data []u8) u32

Writes data to a register of the I2C device.

• reg (u8): Register address to write to.
• data ([]u8): Data to write.

Returns the number of bytes written.

---

Function write_reg(reg u8, value u8) u32

Writes a value to a register of the I2C device.

• reg (u8): Register address to write to.
• value (u8): Value to write.

Returns the number of bytes written.

---

Function disconnect()

Disconnects from the I2C device.

---

Function is_forced() bool

Checks if the connection to the I2C device was forced. Returns true if the connection was forced, otherwise false.

---

Functon is_connected() bool

Checks if the connection to the I2C device is established. Returns true if connected, otherwise false.

---

Function name() string

Gets the name of the I2C device. Returns the name of the device.

---

Function filename() string

Gets the file path of the I2C device. Returns the file path of the device.

---

Function address() u8

Gets the address of the I2C device. Returns the address of the device.

---

Function fd() int

Gets the file descriptor of the I2C device. Returns the file descriptor.

---

Function set_retries(retries int) bool

Sets the number of retries for I2C communication.

• retries (int): The number of retries to set.

Returns (bool): true if the retries were successfully set, otherwise false.

---

Function set_timeout(timeout_ms int) bool

Sets the timeout for I2C communication.

• timeout_ms (int): Timeout value in milliseconds.

Returns (bool): true if the timeout was successfully set, otherwise false.

---

Function is_10bit() bool

Checks if the I2C device address is 10-bit. Returns (bool): true if the I2C device address is 10-bit, otherwise false.

---

Function str() string

Returns a formatted string representing the I2C device.

---

Example

module main

import time
import vi2c

fn main() {
	mut ic2_dev := vi2c.new('/dev/i2c-9', 0x48, 'Temp sensor')

	println(ic2_dev)

	if !ic2_dev.connect(true) {
		println('Failed to connect')
		return
	}

	println(ic2_dev)

	for _ in 1 .. 100 {
		len, data := ic2_dev.read_data_from_reg(~0, 2)

		if len == 2 {
			val := 0.00390625 * f32(u32(data[0]) << 8 | u32(data[1]))
			println('data: <${data.hex()}> temp: ${val} *C')
		}
		time.sleep(1000000000)
	}

	ic2_dev.disconnect()
}

Compile

cd ~/.vmodules
cd vi2c/playground/

To compile it for Linux host machine (x64/x86-64), make sure to specify the include path:

v -cflags '-I /usr/include/' . -o test_i2c_comm_x64

To cross-compile it for Aarch64, make sure that aarch64-linux-gnu-gcc and corresponding libraries are installed. Set aarch64-linux-gnu-gcc as -cc compiler, disable and add the include of Aarch64 - in this case /usr/aarch64-linux-gnu/include/.

v -cc aarch64-linux-gnu-gcc -gc none -cflags '--static -I /usr/aarch64-linux-gnu/include/' test_i2c_comm.v -o test_i2c_comm_aa64

NOTE: Please note that the library and the example code are tested in my Ubuntu 20.4 and an Aarch64 machine.