uI2C.h File Reference

Low level utility for I2C communication on Raspberry Pi using lgpio library. More...

#include <cstring>
#include <errno.h>
#include <fcntl.h>
#include <iostream>
#include <termios.h>
#include <unistd.h>

Go to the source code of this file.

Macros
#define	ACK   'O'
#define	NACK   'N'
#define	RFLAGS_SIZE   1
	Size of the return flags in bytes.
#define	MAX_BUFFER   4
	Maximum size of I2C Payload in bytes.

Functions
int	openI2CDevHandle (const int dev_addr)
	Initiates an I2C device on the bus.
int	readFromI2CDev (const int dev_handle, const int reg, char *buffer, const int data_length)
	reads block of bytes from device to buffer
int	writeToI2CDev (const int dev_handle, const int reg, char *tx_buffer, const int data_length, char *RFLAGS_buffer)
	writes block of bytes from buffer to device
int	closeI2CDevHandle (int &dev_handle)
	close an I2C device on the bus

Detailed Description

Low level utility for I2C communication on Raspberry Pi using lgpio library.

Author

sbstorz

Version

0.1

Date

2025-05-28

Copyright

Copyright (c) 2025

lgpio needs to be installed and linked! Installation:

cd ~
sudo apt update
sudo apt install -y swig
wget https://github.com/joan2937/lg/archive/master.zip
unzip master.zip
cd lg-master
make
sudo make install
cd ..
sudo rm -rf lg-master
rm master.zip

bash

Macro Definition Documentation

ACK

#define ACK   'O'

MAX_BUFFER

#define MAX_BUFFER   4

Maximum size of I2C Payload in bytes.

4 bytes used to transmit floats and int32_t

NACK

#define NACK   'N'

RFLAGS_SIZE

#define RFLAGS_SIZE   1

Size of the return flags in bytes.

Only one byte used and hence set to 1.

Function Documentation

closeI2CDevHandle()

int closeI2CDevHandle

(

int &

dev_handle

)

close an I2C device on the bus

Parameters

dev_handle

device handle obtained from openI2CDevHandle

Returns

0 on OK, negative on error.

openI2CDevHandle()

int openI2CDevHandle

(

const int

dev_addr

)

Initiates an I2C device on the bus.

Parameters

dev_addr

7-bit device adress [0 - 0x7F]

Returns

the device handle, negative on error.

readFromI2CDev()

int readFromI2CDev	(	const int	dev_handle,
		const int	reg,
		char *	buffer,
		const int	data_length
	)

reads block of bytes from device to buffer

Parameters

dev_handle	device handle obtained from openI2CDevHandle
reg	the command/data register
buffer	pointer to data buffer to hold received values
data_length	number of bytes to read

Returns

number of bytes read, negative on error.

writeToI2CDev()

int writeToI2CDev	(	const int	dev_handle,
		const int	reg,
		char *	tx_buffer,
		const int	data_length,
		char *	RFLAGS_buffer
	)

writes block of bytes from buffer to device

Parameters

dev_handle	device handle obtained from openI2CDevHandle
reg	the command/data register
tx_buffer	pointer to data buffer holding the data to send
data_length	number of bytes to send
RFLAGS_buffer	buffer to hold returned flags

Returns

0 on OK, negative on error.