pi

README

Raspberry Pi IO

I/O utilities for Raspberry Pi.

Copyright and Licensing

Copyright (c) 2020 Peter Hagelund

This software is licensed under the MIT License

See LICENSE.txt

Installing

go get -u github.com/peterhagelund/go-pi

Using

TODO

Documentation

Overview

Package pi contains functionality to use the various I/O hardware of a Raspberry Pi, such as GPIO, I2C and the camera module.

Index

• Constants
• type Camera
  • func OpenCamera(path string) (Camera, error)
• type Direction
• type FrameSize
• type GPIO
  • func NewGPIO(pin Pin, direction Direction) (GPIO, error)
• type I2CBus
  • func OpenI2CBus(path string) (I2CBus, error)
• type Pin
• type Value

Constants

const (
	// I2CRetries specifies the number of times a device should be polled when not acknowledging.
	I2CRetries uint32 = 0x00000701 + iota
	// I2CTimeout specifies the timeout in units of 10 ms.
	I2CTimeout
	// I2CSlave specifies the use this slave address.
	I2CSlave
	// I2CTenBit sets the use of ten-bit addresses (0 == 7 bits; not 0 == 10 bits).
	I2CTenBit
	// I2CFuncs gets the adapter functionality mask.
	I2CFuncs
	// I2CSlaveForce specifies the use of this slave address even if it's already in use by a driver.
	I2CSlaveForce
	// I2CRdWr specifieds the use of a combined read/write )on stop only).
	I2CRdWr
	// I2CPEC enables packet error checking.
	I2CPEC
)

const Bcm2708Base int64 = 0x2000000

Bcm2708Base is the BCM 2708 base address.

const GpClr0 int = 10

GpClr0 is the register number for GPCLR0.

const GpLev0 int = 13

GpLev0 is the register number for GPLEV0.

const GpSet0 int = 7

GpSet0 is the register number for GPSET0.

const GpioOffset int64 = 0x20000

GpioOffset is the GPIO offset into the BCM2708 register space.

const PageSize int = 1 << 12

PageSize (4K) is page size for the BCM 2708 GPIO register space.

Types

type Camera

type Camera interface {
	io.Closer
	// Driver returns the camera driver name.
	Driver() (string, error)
	// Card rturns the camera card name.
	Card() (string, error)
	// BusInfo returns the camera bus info.
	BusInfo() (string, error)
	// Formats returns the supported formats.
	Formats() ([]string, error)
	// FrameSizes returns the supported frame sizes for a given format.
	FrameSizes(desc string) ([]*FrameSize, error)
	// SetFormat sets the format and frame size.
	SetFormat(desc string, width uint32, height uint32) (uint32, uint32, error)
	// GrabFrame grabs a single frame.
	GrabFrame() ([]byte, error)
	// GrabImage grabs a single frame and returns it as an image.
	GrabImage() (image.Image, string, error)
}

Camera defines the behavior of a Camera.

func OpenCamera

func OpenCamera(path string) (Camera, error)

OpenCamera opens the camera device at the specified path.

type Direction

type Direction uint8

Direction is the GPIO direction type.

const (
	// DirectionInput is the input direction.
	DirectionInput Direction = iota
	// DirectionOutput is the output direction.
	DirectionOutput
)

type FrameSize

type FrameSize struct {
	// IsDiscreet indicates whether or not this frame size is discreet.
	IsDiscreet bool
	// IsStepwise indicates whether or not this frame size is stepwise.
	IsStepwise bool
	// IsContinuous indicates whether or not this frame size is continuous.
	IsContinuous bool
	// Width is the discreet width.
	Width uint32
	// Height is the discreet height.
	Height uint32
	// MinWidth is the minimum width.
	MinWidth uint32
	// MaxWidth is the maximum width.
	MaxWidth uint32
	// StepWidth is the step width.
	StepWidth uint32
	// MinHeight is the minimum height.
	MinHeight uint32
	// MaxHeight is the maximum height.
	MaxHeight uint32
	// StepHeight is the step height.
	StepHeight uint32
}

FrameSize is an encapsulation of a support frame size or steps.

type GPIO

type GPIO interface {
	io.Closer
	Direction() Direction
	Pin() Pin
	Value() (Value, error)
	SetValue(value Value) error
}

GPIO represents a single GPIO pin.

func NewGPIO

func NewGPIO(pin Pin, direction Direction) (GPIO, error)

NewGPIO creates and returns a new GPIO instance

type I2CBus

type I2CBus interface {
	io.Reader
	io.Writer
	io.Closer
	// SetSlave addresses a specific slave.
	SetSlave(address uint8) error
}

I2CBus defines the behavior of an I2C bus).

func OpenI2CBus

func OpenI2CBus(path string) (I2CBus, error)

OpenI2CBus opens the I2C bus at the specified path.

type Pin

type Pin uint8

Pin is the GPIO pin type.

const (
	// GPIO2 is GPIO pin 2.
	GPIO2 Pin = iota + 2
	// GPIO3 is GPIO pin 3.
	GPIO3
	// GPIO4 is GPIO pin 4.
	GPIO4
	// GPIO5 is GPIO pin 5.
	GPIO5
	// GPIO6 is GPIO pin 6.
	GPIO6
	// GPIO7 is GPIO pin 7.
	GPIO7
	// GPIO8 is GPIO pin 8.
	GPIO8
	// GPIO9 is GPIO pin 9.
	GPIO9
	// GPIO10 is GPIO pin 10.
	GPIO10
	// GPIO11 is GPIO pin 11.
	GPIO11
	// GPIO12 is GPIO pin 12.
	GPIO12
	// GPIO13 is GPIO pin 13.
	GPIO13
	// GPIO14 is GPIO pin 14.
	GPIO14
	// GPIO15 is GPIO pin 15.
	GPIO15
	// GPIO16 is GPIO pin 16.
	GPIO16
	// GPIO17 is GPIO pin 17.
	GPIO17
	// GPIO18 is GPIO pin 18.
	GPIO18
	// GPIO19 is GPIO pin 19.
	GPIO19
	// GPIO20 is GPIO pin 20.
	GPIO20
	// GPIO21 is GPIO pin 21.
	GPIO21
	// GPIO22 is GPIO pin 22.
	GPIO22
	// GPIO23 is GPIO pin 23.
	GPIO23
	// GPIO24 is GPIO pin 24.
	GPIO24
	// GPIO25 is GPIO pin 25.
	GPIO25
	// GPIO26 is GPIO pin 26.
	GPIO26
	// GPIO27 is GPIO pin 27.
	GPIO27
)

type Value

type Value uint8

Value is the GPIO value type.

const (
	// ValueOff represents a GPIO voltage equivalent to off.
	ValueOff Value = iota
	// ValueOn represents a GPIO voltage equivalent to on.
	ValueOn
)