const LED = IO2

Built-in LED on some ESP32 boards.

const (
	CLK	Pin	= 6
	CMD	Pin	= 11
	IO0	Pin	= 0
	IO1	Pin	= 1
	IO10	Pin	= 10
	IO16	Pin	= 16
	IO17	Pin	= 17
	IO18	Pin	= 18
	IO19	Pin	= 19
	IO2	Pin	= 2
	IO21	Pin	= 21
	IO22	Pin	= 22
	IO23	Pin	= 23
	IO25	Pin	= 25
	IO26	Pin	= 26
	IO27	Pin	= 27
	IO3	Pin	= 3
	IO32	Pin	= 32
	IO33	Pin	= 33
	IO34	Pin	= 34
	IO35	Pin	= 35
	IO36	Pin	= 36
	IO39	Pin	= 39
	IO4	Pin	= 4
	IO5	Pin	= 5
	IO9	Pin	= 9
	RXD	Pin	= 3
	SD0	Pin	= 7
	SD1	Pin	= 8
	SD2	Pin	= 9
	SD3	Pin	= 10
	SVN	Pin	= 39
	SVP	Pin	= 36
	TCK	Pin	= 13
	TD0	Pin	= 15
	TDI	Pin	= 12
	TMS	Pin	= 14
	TXD	Pin	= 1
const (

SPI pins

const (

I2C pins

const (
	ADC0	Pin	= IO34
	ADC1	Pin	= IO35
	ADC2	Pin	= IO36
	ADC3	Pin	= IO39

ADC pins

const (

UART0 pins

const (

UART1 pins

const (
	PWM0_PIN	Pin	= IO2
	PWM1_PIN	Pin	= IO0
	PWM2_PIN	Pin	= IO4

PWM pins

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).

const (
	PinOutput	PinMode	= iota


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")
var (
	ErrInvalidSPIBus = errors.New("machine: invalid SPI bus")
var (
	UART0	= UART{Bus: esp.UART0, Buffer: NewRingBuffer()}
	UART1	= UART{Bus: esp.UART1, Buffer: NewRingBuffer()}
	UART2	= UART{Bus: esp.UART2, Buffer: NewRingBuffer()}
var (
	// SPI0 and SPI1 are reserved for use by the caching system etc.
	SPI2	= SPI{esp.SPI2}
	SPI3	= SPI{esp.SPI3}

func CPUFrequency

func CPUFrequency() uint32

CPUFrequency returns the current CPU frequency of the chip. Currently it is a fixed frequency but it may allow changing in the future.

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

type ADC

type ADC struct {
	Pin Pin

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 PWM

type PWM struct {
	Pin Pin

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)

Configure this pin with the given configuration.

func (Pin) Get

func (p Pin) Get() bool

Get returns the current value of a GPIO pin when the pin is configured as an input.

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) PortMaskClear

func (p Pin) PortMaskClear() (*uint32, uint32)

Return the register and mask to disable a given GPIO pin. This can be used to implement bit-banged drivers.

Warning: only use this on an output pin!

func (Pin) PortMaskSet

func (p Pin) PortMaskSet() (*uint32, uint32)

Return the register and mask to enable a given GPIO pin. This can be used to implement bit-banged drivers.

Warning: only use this on an output pin!

func (Pin) Set

func (p Pin) Set(value bool)

Set the pin to high or low. Warning: only use this on an output pin!

type PinConfig

type PinConfig struct {
	Mode PinMode

type PinMode

type PinMode uint8

type RingBuffer

type RingBuffer struct {
	rxbuffer	[bufferSize]volatile.Register8
	head		volatile.Register8
	tail		volatile.Register8

RingBuffer is ring buffer implementation inspired by post at

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 *esp.SPI_Type

Serial Peripheral Interface on the ESP32.

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig) error

Configure and make the SPI peripheral ready to use.

func (SPI) Transfer

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

Transfer writes/reads a single byte using the SPI interface. If you need to transfer larger amounts of data, Tx will be faster.

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. This is accomplished by sending zero bits if r is bigger than w or discarding the incoming data if w is bigger than r.

type SPIConfig

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

SPIConfig configures a SPI peripheral on the ESP32. Make sure to set at least SCK, SDO and SDI (possibly to NoPin if not in use). The default for LSBFirst (false) and Mode (0) are good for most applications. The frequency defaults to 1MHz if not set but can be configured up to 40MHz. Possible values are 40MHz and integer divisions from 40MHz such as 20MHz, 13.3MHz, 10MHz, 8MHz, etc.

type UART

type UART struct {
	Bus	*esp.UART_Type
	Buffer	*RingBuffer

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)

func (UART) Read

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

Read from the RX buffer.

func (UART) ReadByte

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

ReadByte reads a single byte from the RX buffer. If there is no data in the buffer, returns an error.

func (UART) Receive

func (uart UART) Receive(data byte)

Receive handles adding data to the UART’s data buffer. Usually called by the IRQ handler for a machine.

func (UART) Write

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

Write data to the UART.

func (UART) WriteByte

func (uart UART) WriteByte(b byte) error

type UARTConfig

type UARTConfig struct {
	BaudRate	uint32
	TX		Pin
	RX		Pin