i2c

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Published: Nov 23, 2019 License: MIT Imports: 6 Imported by: 162

README

I2C-bus interaction of peripheral sensors with Raspberry PI embedded linux or respective clones

Build Status Go Report Card GoDoc MIT License

This library written in Go programming language intended to activate and interact with the I2C bus by reading and writing data.

Compatibility

Tested on Raspberry Pi 1 (model B), Raspberry Pi 3 B+, Banana Pi (model M1), Orange Pi Zero, Orange Pi One.

Golang usage

func main() {
  // Create new connection to I2C bus on 2 line with address 0x27
  i2c, err := i2c.NewI2C(0x27, 2)
  if err != nil { log.Fatal(err) }
  // Free I2C connection on exit
  defer i2c.Close()
  ....
  // Here goes code specific for sending and reading data
  // to and from device connected via I2C bus, like:
  _, err := i2c.Write([]byte{0x1, 0xF3})
  if err != nil { log.Fatal(err) }
  ....
}

Tutorial

My repositories contain quite a lot projects, which use i2c library as a starting point to interact with various peripheral devices and sensors for use on embedded Linux devices. All these libraries start with a standard call to open I2C-connection to specific bus line and address, than pass i2c instance to device.

In its turn, go-i2c use go-logger library to output debug and other notification's lines which produce all necessary levels of logging. You can manage what level of verbosity you would like to see, by adding call:

// Uncomment/comment next line to suppress/increase verbosity of output
logger.ChangePackageLogLevel("i2c", logger.InfoLevel)

Once you put this call, it will decrease verbosity from default "Debug" up to next "Info" level, reducing the number of low-level console outputs that occur during interaction with the I2C bus. Please, find examples in corresponding I2C-driven sensors among my projects.

You will find here the list of all devices and sensors supported by me, that reference this library:

Getting help

GoDoc documentation

Troubleshooting

  • How to obtain fresh Golang installation to RPi device (either any RPi clone): If your RaspberryPI golang installation taken by default from repository is outdated, you may consider to install actual golang manually from official Golang site. Download tar.gz file containing armv6l in the name. Follow installation instructions.

  • How to enable I2C bus on RPi device: If you employ RaspberryPI, use raspi-config utility to activate i2c-bus on the OS level. Go to "Interfacing Options" menu, to active I2C bus. Probably you will need to reboot to load i2c kernel module. Finally you should have device like /dev/i2c-1 present in the system.

  • How to find I2C bus allocation and device address: Use i2cdetect utility in format "i2cdetect -y X", where X may vary from 0 to 5 or more, to discover address occupied by peripheral device. To install utility you should run apt install i2c-tools on debian-kind system. i2cdetect -y 1 sample output:

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    70: -- -- -- -- -- -- 76 --    
    

License

Go-i2c is licensed under MIT License.

Documentation

Index

Constants

View Source
const (
	I2C_SLAVE = C.I2C_SLAVE
)

Get I2C_SLAVE constant value from Linux OS I2C declaration file.

Variables

This section is empty.

Functions

This section is empty.

Types

type I2C

type I2C struct {
	// contains filtered or unexported fields
}

I2C represents a connection to I2C-device.

func NewI2C

func NewI2C(addr uint8, bus int) (*I2C, error)

NewI2C opens a connection for I2C-device. SMBus (System Management Bus) protocol over I2C supported as well: you should preliminary specify register address to read from, either write register together with the data in case of write operations.

func (*I2C) Close

func (v *I2C) Close() error

Close I2C-connection.

func (*I2C) GetAddr

func (v *I2C) GetAddr() uint8

GetAddr return device occupied address in the bus.

func (*I2C) GetBus

func (v *I2C) GetBus() int

GetBus return bus line, where I2C-device is allocated.

func (*I2C) ReadBytes

func (v *I2C) ReadBytes(buf []byte) (int, error)

ReadBytes read bytes from I2C-device. Number of bytes read correspond to buf parameter length.

func (*I2C) ReadRegBytes

func (v *I2C) ReadRegBytes(reg byte, n int) ([]byte, int, error)

ReadRegBytes read count of n byte's sequence from I2C-device starting from reg address. SMBus (System Management Bus) protocol over I2C.

func (*I2C) ReadRegS16BE

func (v *I2C) ReadRegS16BE(reg byte) (int16, error)

ReadRegS16BE reads signed big endian word (16 bits) from I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) ReadRegS16LE

func (v *I2C) ReadRegS16LE(reg byte) (int16, error)

ReadRegS16LE reads signed little endian word (16 bits) from I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) ReadRegU16BE

func (v *I2C) ReadRegU16BE(reg byte) (uint16, error)

ReadRegU16BE reads unsigned big endian word (16 bits) from I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) ReadRegU16LE

func (v *I2C) ReadRegU16LE(reg byte) (uint16, error)

ReadRegU16LE reads unsigned little endian word (16 bits) from I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) ReadRegU8

func (v *I2C) ReadRegU8(reg byte) (byte, error)

ReadRegU8 reads byte from I2C-device register specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) WriteBytes

func (v *I2C) WriteBytes(buf []byte) (int, error)

WriteBytes send bytes to the remote I2C-device. The interpretation of the message is implementation-dependent.

func (*I2C) WriteRegS16BE

func (v *I2C) WriteRegS16BE(reg byte, value int16) error

WriteRegS16BE writes signed big endian word (16 bits) value to I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) WriteRegS16LE

func (v *I2C) WriteRegS16LE(reg byte, value int16) error

WriteRegS16LE writes signed little endian word (16 bits) value to I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) WriteRegU16BE

func (v *I2C) WriteRegU16BE(reg byte, value uint16) error

WriteRegU16BE writes unsigned big endian word (16 bits) value to I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) WriteRegU16LE

func (v *I2C) WriteRegU16LE(reg byte, value uint16) error

WriteRegU16LE writes unsigned little endian word (16 bits) value to I2C-device starting from address specified in reg. SMBus (System Management Bus) protocol over I2C.

func (*I2C) WriteRegU8

func (v *I2C) WriteRegU8(reg byte, value byte) error

WriteRegU8 writes byte to I2C-device register specified in reg. SMBus (System Management Bus) protocol over I2C.

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