package spi

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

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

Deprecated

This package is not maintained anymore. An actively supported cross-platform alternative is https://periph.io/.

package main

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

func main() {
	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 ¶

• Constants
• type Devfs
• func (d *Devfs) Open() (driver.Conn, error)
• type Device
• func Open(o driver.Opener) (*Device, error)
• func (d *Device) Close() error
• func (d *Device) SetBitOrder(o Order) error
• func (d *Device) SetBitsPerWord(bits int) error
• func (d *Device) SetCSChange(leaveEnabled bool) error
• func (d *Device) SetDelay(t time.Duration) error
• func (d *Device) SetMaxSpeed(speed int) error
• func (d *Device) SetMode(mode Mode) error
• func (d *Device) Tx(w, r []byte) error
• type Mode
• type Order

Examples ¶

• package

Constants ¶

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

const (
	MSBFirst = Order(0)
	LSBFirst = Order(1)
)

Types ¶

type Devfs ¶

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 overridden by the device's driver.
	// Required.
	Mode Mode

	// MaxSpeed is the max clock speed (Hz) and can be overridden 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 ¶

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

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

type Device ¶

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

func Open ¶

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

func (*Device) Close ¶

func (d *Device) Close() error

Close closes the SPI device and releases the related resources.

func (*Device) SetBitOrder ¶

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 ¶

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 ¶

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

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

func (*Device) SetDelay ¶

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

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

func (*Device) SetMaxSpeed ¶

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

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

func (*Device) SetMode ¶

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 ¶

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 ¶

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 ¶

type Order int

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

Source Files ¶

devfs.go spi.go

Directories ¶