Documentation
¶
Overview ¶
Package i2c defines the API to communicate with devices over the I²C protocol.
As described in https://periph.io/x/periph/conn#hdr-Concepts, periph.io uses the concepts of Bus, Port and Conn.
In the package i2c, 'Port' is not exposed, since once you know the I²C device address, there's no unconfigured Port to configure.
Instead, the package includes the adapter 'Dev' to directly convert an I²C bus 'i2c.Bus' into a connection 'conn.Conn' by only specifying the device I²C address.
See https://en.wikipedia.org/wiki/I%C2%B2C for more information.
Example ¶
package main
import (
"fmt"
"log"
"periph.io/x/periph/conn/i2c"
"periph.io/x/periph/conn/i2c/i2creg"
"periph.io/x/periph/host"
)
func main() {
// Make sure periph is initialized.
if _, err := host.Init(); err != nil {
log.Fatal(err)
}
// Use i2creg I²C bus registry to find the first available I²C bus.
b, err := i2creg.Open("")
if err != nil {
log.Fatal(err)
}
defer b.Close()
// Dev is a valid conn.Conn.
d := &i2c.Dev{Addr: 23, Bus: b}
// Send a command 0x10 and expect a 5 bytes reply.
write := []byte{0x10}
read := make([]byte, 5)
if err := d.Tx(write, read); err != nil {
log.Fatal(err)
}
fmt.Printf("%v\n", read)
}
Output:
Index ¶
Examples ¶
Constants ¶
const ( SCL pin.Func = "I2C_SCL" // Clock SDA pin.Func = "I2C_SDA" // Data )
Well known pin functionality.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Addr ¶
type Addr uint16
Addr is an I²C slave address.
Example (Flag) ¶
package main
import (
"flag"
"periph.io/x/periph/conn/i2c"
)
func main() {
var addr i2c.Addr
flag.Var(&addr, "addr", "i2c device address")
flag.Parse()
}
Output:
type Bus ¶
type Bus interface {
String() string
// Tx does a transaction at the specified device address.
//
// Write is done first, then read. One of 'w' or 'r' can be omitted for a
// unidirectional operation.
Tx(addr uint16, w, r []byte) error
// SetSpeed changes the bus speed, if supported.
//
// On linux due to the way the I²C sysfs driver is exposed in userland,
// calling this function will likely affect *all* I²C buses on the host.
SetSpeed(f physic.Frequency) error
}
Bus defines the interface a concrete I²C driver must implement.
This interface is consummed by a device driver for a device sitting on a bus.
This interface doesn't implement conn.Conn since a device address must be specified. Use i2cdev.Dev as an adapter to get a conn.Conn compatible object.
type BusCloser ¶
BusCloser is an I²C bus that can be closed.
This interface is meant to be handled by the application and not the device driver. A device driver doesn't "own" a bus, hence it must operate on a Bus, not a BusCloser.
type Dev ¶
Dev is a device on a I²C bus.
It implements conn.Conn.
It saves from repeatedly specifying the device address.
type Pins ¶
type Pins interface {
// SCL returns the CLK (clock) pin.
SCL() gpio.PinIO
// SDA returns the DATA pin.
SDA() gpio.PinIO
}
Pins defines the pins that an I²C bus interconnect is using on the host.
It is expected that a implementer of Bus also implement Pins but this is not a requirement.
Example ¶
package main
import (
"fmt"
"log"
"periph.io/x/periph/conn/i2c"
"periph.io/x/periph/conn/i2c/i2creg"
"periph.io/x/periph/host"
)
func main() {
// Make sure periph is initialized.
if _, err := host.Init(); err != nil {
log.Fatal(err)
}
// Use i2creg I²C port registry to find the first available I²C bus.
b, err := i2creg.Open("")
if err != nil {
log.Fatal(err)
}
defer b.Close()
// Prints out the gpio pin used.
if p, ok := b.(i2c.Pins); ok {
fmt.Printf("SDA: %s", p.SDA())
fmt.Printf("SCL: %s", p.SCL())
}
}
Output:
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
|
Package i2creg defines I²C bus registry to list buses present on the host.
|
Package i2creg defines I²C bus registry to list buses present on the host. |
|
Package i2ctest is meant to be used to test drivers over a fake I²C bus.
|
Package i2ctest is meant to be used to test drivers over a fake I²C bus. |