exp: golang.org/x/exp/io/spi Index | Examples | Files | Directories

package spi

import "golang.org/x/exp/io/spi"

Package spi allows users to read from and write to an SPI device.

Example illustrates a program that drives an APA-102 LED strip.

Code:

dev, err := spi.Open(&spi.Devfs{
    Dev:      "/dev/spidev0.1",
    Mode:     spi.Mode3,
    MaxSpeed: 500000,
})
if err != nil {
    panic(err)
}
defer dev.Close()

if err := dev.Tx([]byte{
    0, 0, 0, 0,
    0xff, 200, 0, 200,
    0xff, 200, 0, 200,
    0xe0, 200, 0, 200,
    0xff, 200, 0, 200,
    0xff, 8, 50, 0,
    0xff, 200, 0, 0,
    0xff, 0, 0, 0,
    0xff, 200, 0, 200,
    0xff, 0xff, 0xff, 0xff,
    0xff, 0xff, 0xff, 0xff,
    0xff, 0xff, 0xff, 0xff,
    0xff, 0xff, 0xff, 0xff,
}, nil); err != nil {
    panic(err)
}

Index

Examples

Package Files

devfs.go spi.go

Constants

const (
    Mode0 = Mode(0)
    Mode1 = Mode(1)
    Mode2 = Mode(2)
    Mode3 = Mode(3)
)
const (
    MSBFirst = Order(0)
    LSBFirst = Order(1)
)

type Devfs Uses

type Devfs struct {
    // Dev is the device to be opened.
    // Device name is usually in the /dev/spidev<bus>.<chip> format.
    // Required.
    Dev string

    // Mode is the SPI mode. SPI mode is a combination of polarity and phases.
    // CPOL is the high order bit, CPHA is the low order. Pre-computed mode
    // values are Mode0, Mode1, Mode2 and Mode3. The value of the mode argument
    // can be overriden by the device's driver.
    // Required.
    Mode Mode

    // MaxSpeed is the max clock speed (Hz) and can be overriden by the device's driver.
    // Required.
    MaxSpeed int64
}

Devfs is an SPI driver that works against the devfs. You need to have loaded the "spidev" Linux module to use this driver.

func (*Devfs) Open Uses

func (d *Devfs) Open() (driver.Conn, error)

Open opens the provided device with the specified options and returns a connection.

type Device Uses

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

func Open Uses

func Open(o driver.Opener) (*Device, error)

func (*Device) Close Uses

func (d *Device) Close() error

Close closes the SPI device and releases the related resources.

func (*Device) SetBitOrder Uses

func (d *Device) SetBitOrder(o Order) error

SetBitOrder sets the bit justification used to transfer SPI words. Valid values are MSBFirst and LSBFirst.

func (*Device) SetBitsPerWord Uses

func (d *Device) SetBitsPerWord(bits int) error

SetBitsPerWord sets how many bits it takes to represent a word, e.g. 8 represents 8-bit words. The default is 8 bits per word.

func (*Device) SetCSChange Uses

func (d *Device) SetCSChange(leaveEnabled bool) error

SetCSChange sets whether to leave the chipselect enabled after a Tx.

func (*Device) SetDelay Uses

func (d *Device) SetDelay(t time.Duration) error

SetDelay sets the amount of pause will be added after each frame write.

func (*Device) SetMaxSpeed Uses

func (d *Device) SetMaxSpeed(speed int) error

SetMaxSpeed sets the maximum clock speed in Hz. The value can be overriden by SPI device's driver.

func (*Device) SetMode Uses

func (d *Device) SetMode(mode Mode) error

SetMode sets the SPI mode. SPI mode is a combination of polarity and phases. CPOL is the high order bit, CPHA is the low order. Pre-computed mode values are Mode0, Mode1, Mode2 and Mode3. The value can be changed by SPI device's driver.

func (*Device) Tx Uses

func (d *Device) Tx(w, r []byte) error

Tx performs a duplex transmission to write w to the SPI device and read len(r) bytes to r. User should not mutate the w and r until this call returns.

type Mode Uses

type Mode int

Mode represents the SPI mode number where clock parity (CPOL) is the high order and clock edge (CPHA) is the low order bit.

type Order Uses

type Order int

Order is the bit justification to be used while transfering words to the SPI device. MSB-first encoding is more popular than LSB-first.

Directories

PathSynopsis
driverPackage driver contains interfaces to be implemented by various SPI implementations.

Package spi imports 6 packages (graph) and is imported by 7 packages. Updated 2017-06-04. Refresh now. Tools for package owners.