machine

package
Version: v0.19.0 Latest Latest
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Published: Jun 30, 2021 License: BSD-3-Clause Imports: 2 Imported by: 2

Documentation

Index

Constants

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

SPI phase and polarity configs CPOL and CPHA

View Source
const NoPin = Pin(0xff)

NoPin explicitly indicates "not a pin". Use this pin if you want to leave one of the pins in a peripheral unconfigured (if supported by the hardware).

Variables

View Source
var (
	ErrInvalidInputPin    = errors.New("machine: invalid input pin")
	ErrInvalidOutputPin   = errors.New("machine: invalid output pin")
	ErrInvalidClockPin    = errors.New("machine: invalid clock pin")
	ErrInvalidDataPin     = errors.New("machine: invalid data pin")
	ErrNoPinChangeChannel = errors.New("machine: no channel available for pin interrupt")
)
View Source
var (
	SPI0  = SPI{0}
	I2C0  = &I2C{0}
	UART0 = &UART{0}
	USB   = &UART{100}
)
View Source
var (
	ErrPWMPeriodTooLong = errors.New("pwm: period too long")
)
View Source
var (
	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
)
View Source
var Serial = UART0

The Serial port always points to the default UART in a simulated environment.

TODO: perhaps this should be a special serial object that outputs via WASI stdout calls.

Functions

func InitADC

func InitADC()

InitADC enables support for ADC peripherals.

Types

type ADC

type ADC struct {
	Pin Pin
}

func (ADC) Configure

func (adc ADC) Configure(ADCConfig)

Configure configures an ADC pin to be able to be used to read data.

func (ADC) Get

func (adc ADC) Get() uint16

Get reads the current analog value from this ADC peripheral.

type ADCConfig

type ADCConfig struct {
	Reference  uint32 // analog reference voltage (AREF) in millivolts
	Resolution uint32 // number of bits for a single conversion (e.g., 8, 10, 12)
	Samples    uint32 // number of samples for a single conversion (e.g., 4, 8, 16, 32)
}

ADCConfig holds ADC configuration parameters. If left unspecified, the zero value of each parameter will use the peripheral's default settings.

type I2C

type I2C struct {
	Bus uint8
}

I2C is a generic implementation of the Inter-IC communication protocol.

func (*I2C) Configure

func (i2c *I2C) Configure(config I2CConfig) error

Configure is intended to setup the I2C interface.

func (*I2C) Tx

func (i2c *I2C) Tx(addr uint16, w, r []byte) error

Tx does a single I2C transaction at the specified address.

type I2CConfig

type I2CConfig struct {
	Frequency uint32
	SCL       Pin
	SDA       Pin
}

I2CConfig is used to store config info for I2C.

type NullSerial

type NullSerial struct {
}

NullSerial is a serial version of /dev/null (or null router): it drops everything that is written to it.

func (NullSerial) Buffered

func (ns NullSerial) Buffered() int

Buffered returns how many bytes are buffered in the UART. It always returns 0 as there are no bytes to read.

func (NullSerial) Configure

func (ns NullSerial) Configure(config UARTConfig) error

Configure does nothing: the null serial has no configuration.

func (NullSerial) ReadByte

func (ns NullSerial) ReadByte() (byte, error)

ReadByte always returns an error because there aren't any bytes to read.

func (NullSerial) Write

func (ns NullSerial) Write(p []byte) (n int, err error)

Write is a no-op: none of the data is being written and it will not return an error.

func (NullSerial) WriteByte

func (ns NullSerial) WriteByte(b byte) error

WriteByte is a no-op: the null serial doesn't write bytes.

type PWMConfig

type PWMConfig struct {
	// PWM period in nanosecond. Leaving this zero will pick a reasonable period
	// value for use with LEDs.
	// If you want to configure a frequency instead of a period, you can use the
	// following formula to calculate a period from a frequency:
	//
	//     period = 1e9 / frequency
	//
	Period uint64
}

PWMConfig allows setting some configuration while configuring a PWM peripheral. A zero PWMConfig is ready to use for simple applications such as dimming LEDs.

type Pin

type Pin uint8

Pin is a single pin on a chip, which may be connected to other hardware devices. It can either be used directly as GPIO pin or it can be used in other peripherals like ADC, I2C, etc.

func (Pin) Configure

func (p Pin) Configure(config PinConfig)

func (Pin) Get

func (p Pin) Get() bool

func (Pin) High

func (p Pin) High()

High sets this GPIO pin to high, assuming it has been configured as an output pin. It is hardware dependent (and often undefined) what happens if you set a pin to high that is not configured as an output pin.

func (Pin) Low

func (p Pin) Low()

Low sets this GPIO pin to low, assuming it has been configured as an output pin. It is hardware dependent (and often undefined) what happens if you set a pin to low that is not configured as an output pin.

func (Pin) Set

func (p Pin) Set(value bool)

type PinConfig

type PinConfig struct {
	Mode PinMode
}

type PinMode

type PinMode uint8

PinMode sets the direction and pull mode of the pin. For example, PinOutput sets the pin as an output and PinInputPullup sets the pin as an input with a pull-up.

const (
	PinInput PinMode = iota
	PinOutput
	PinInputPullup
	PinInputPulldown
)

type RingBuffer

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

RingBuffer is ring buffer implementation inspired by post at https://www.embeddedrelated.com/showthread/comp.arch.embedded/77084-1.php

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

func (*RingBuffer) Clear

func (rb *RingBuffer) Clear()

Clear resets the head and tail pointer to zero.

func (*RingBuffer) Get

func (rb *RingBuffer) Get() (byte, bool)

Get returns a byte from the buffer. If the buffer is empty, the method will return a false as the second value.

func (*RingBuffer) Put

func (rb *RingBuffer) Put(val byte) bool

Put stores a byte in the buffer. If the buffer is already full, the method will return false.

func (*RingBuffer) Used

func (rb *RingBuffer) Used() uint8

Used returns how many bytes in buffer have been used.

type SPI

type SPI struct {
	Bus uint8
}

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig)

func (SPI) Transfer

func (spi SPI) Transfer(w byte) (byte, error)

Transfer writes/reads a single byte using the SPI interface.

func (SPI) Tx

func (spi SPI) Tx(w, r []byte) error

Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read interface, there must always be the same number of bytes written as bytes read. The Tx method knows about this, and offers a few different ways of calling it.

This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer. Note that the tx and rx buffers must be the same size:

spi.Tx(tx, rx)

This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros until all the bytes in the command packet have been received:

spi.Tx(tx, nil)

This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":

spi.Tx(nil, rx)

type SPIConfig

type SPIConfig struct {
	Frequency uint32
	SCK       Pin
	SDO       Pin
	SDI       Pin
	Mode      uint8
}

type UART

type UART struct {
	Bus uint8
}

func (*UART) Buffered

func (uart *UART) Buffered() int

Buffered returns the number of bytes currently stored in the RX buffer.

func (*UART) Configure

func (uart *UART) Configure(config UARTConfig)

Configure the UART.

func (*UART) Read

func (uart *UART) Read(data []byte) (n int, err error)

Read from the UART.

func (*UART) ReadByte

func (uart *UART) ReadByte() (byte, error)

ReadByte reads a single byte from the UART.

func (*UART) Write

func (uart *UART) Write(data []byte) (n int, err error)

Write to the UART.

func (*UART) WriteByte

func (uart *UART) WriteByte(b byte) error

WriteByte writes a single byte to the UART.

type UARTConfig

type UARTConfig struct {
	BaudRate uint32
	TX       Pin
	RX       Pin
}

UARTConfig is a struct with which a UART (or similar object) can be configured. The baud rate is usually respected, but TX and RX may be ignored depending on the chip and the type of object.

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