const HasLowFrequencyCrystal = false

The micro:bit does not have a 32kHz crystal on board.

const (
	LED	= P13
const (
	BUTTONB	Pin	= P11

Buttons on the micro:bit v2 (A and B)

const (
	UART_TX_PIN	Pin	= P34
	UART_RX_PIN	Pin	= P33

UART pins

const (
	ADC0	Pin	= P0
	ADC1	Pin	= P1
	ADC2	Pin	= P2

ADC pins

const (
	SDA0_PIN	Pin	= P30
	SCL0_PIN	Pin	= P31

I2C0 (internal) pins

const (
	SDA1_PIN	Pin	= P20
	SCL1_PIN	Pin	= P19

I2C1 (external) pins

const (
	SPI0_SCK_PIN	Pin	= P13
	SPI0_SDO_PIN	Pin	= P15
	SPI0_SDI_PIN	Pin	= P14

SPI pins

const (
	P0	Pin	= 2
	P1	Pin	= 3
	P2	Pin	= 4
	P3	Pin	= 31
	P4	Pin	= 28
	P5	Pin	= 14
	P6	Pin	= 37
	P7	Pin	= 11
	P8	Pin	= 10
	P9	Pin	= 9
	P10	Pin	= 30
	P11	Pin	= 23
	P12	Pin	= 12
	P13	Pin	= 17
	P14	Pin	= 1
	P15	Pin	= 13
	P16	Pin	= 34
	P19	Pin	= 26
	P20	Pin	= 32
	P21	Pin	= 21
	P22	Pin	= 22
	P23	Pin	= 15
	P24	Pin	= 24
	P25	Pin	= 19
	P26	Pin	= 36
	P27	Pin	= 0
	P28	Pin	= 20
	P29	Pin	= 5
	P30	Pin	= 16
	P31	Pin	= 8
	P32	Pin	= 25
	P33	Pin	= 40
	P34	Pin	= 6

GPIO/Analog pins

const (
	LED_COL_1	Pin	= P0_28
	LED_COL_2	Pin	= P0_11
	LED_COL_3	Pin	= P0_31
	LED_COL_4	Pin	= P1_05
	LED_COL_5	Pin	= P0_30
	LED_ROW_1	Pin	= P0_21
	LED_ROW_2	Pin	= P0_22
	LED_ROW_3	Pin	= P0_15
	LED_ROW_4	Pin	= P0_24
	LED_ROW_5	Pin	= P0_19

LED matrix pins

const (
	TWI_FREQ_100KHZ	= 100000
	TWI_FREQ_400KHZ	= 400000

TWI_FREQ is the I2C bus speed. Normally either 100 kHz, or 400 kHz for high-speed bus.

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 (
	PinInput		PinMode	= (nrf.GPIO_PIN_CNF_DIR_Input << nrf.GPIO_PIN_CNF_DIR_Pos) | (nrf.GPIO_PIN_CNF_INPUT_Connect << nrf.GPIO_PIN_CNF_INPUT_Pos)
	PinInputPullup		PinMode	= PinInput | (nrf.GPIO_PIN_CNF_PULL_Pullup << nrf.GPIO_PIN_CNF_PULL_Pos)
	PinInputPulldown	PinMode	= PinInput | (nrf.GPIO_PIN_CNF_PULL_Pulldown << nrf.GPIO_PIN_CNF_PULL_Pos)
	PinOutput		PinMode	= (nrf.GPIO_PIN_CNF_DIR_Output << nrf.GPIO_PIN_CNF_DIR_Pos) | (nrf.GPIO_PIN_CNF_INPUT_Disconnect << nrf.GPIO_PIN_CNF_INPUT_Pos)
const (
	PinRising	PinChange	= nrf.GPIOTE_CONFIG_POLARITY_LoToHi
	PinFalling	PinChange	= nrf.GPIOTE_CONFIG_POLARITY_HiToLo
	PinToggle	PinChange	= nrf.GPIOTE_CONFIG_POLARITY_Toggle

Pin change interrupt constants for SetInterrupt.

const (
	P0_00	Pin	= 0
	P0_01	Pin	= 1
	P0_02	Pin	= 2
	P0_03	Pin	= 3
	P0_04	Pin	= 4
	P0_05	Pin	= 5
	P0_06	Pin	= 6
	P0_07	Pin	= 7
	P0_08	Pin	= 8
	P0_09	Pin	= 9
	P0_10	Pin	= 10
	P0_11	Pin	= 11
	P0_12	Pin	= 12
	P0_13	Pin	= 13
	P0_14	Pin	= 14
	P0_15	Pin	= 15
	P0_16	Pin	= 16
	P0_17	Pin	= 17
	P0_18	Pin	= 18
	P0_19	Pin	= 19
	P0_20	Pin	= 20
	P0_21	Pin	= 21
	P0_22	Pin	= 22
	P0_23	Pin	= 23
	P0_24	Pin	= 24
	P0_25	Pin	= 25
	P0_26	Pin	= 26
	P0_27	Pin	= 27
	P0_28	Pin	= 28
	P0_29	Pin	= 29
	P0_30	Pin	= 30
	P0_31	Pin	= 31
	P1_00	Pin	= 32
	P1_01	Pin	= 33
	P1_02	Pin	= 34
	P1_03	Pin	= 35
	P1_04	Pin	= 36
	P1_05	Pin	= 37
	P1_06	Pin	= 38
	P1_07	Pin	= 39
	P1_08	Pin	= 40
	P1_09	Pin	= 41
	P1_10	Pin	= 42
	P1_11	Pin	= 43
	P1_12	Pin	= 44
	P1_13	Pin	= 45
	P1_14	Pin	= 46
	P1_15	Pin	= 47

Hardware pins


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 (
	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
var (
	// NRF_UART0 is the hardware UART on the NRF SoC.
	NRF_UART0 = UART{Buffer: NewRingBuffer()}


var (
	I2C0	= I2C{Bus: nrf.TWI0}
	I2C1	= I2C{Bus: nrf.TWI1}

There are 2 I2C interfaces on the NRF.

var (
var (
	SPI0	= SPI{Bus: nrf.SPIM0}
	SPI1	= SPI{Bus: nrf.SPIM1}
	SPI2	= SPI{Bus: nrf.SPIM2}

There are 3 SPI interfaces on the NRF528xx.

func CPUFrequency

func CPUFrequency() uint32

func InitADC

func InitADC()

InitADC initializes the registers needed for ADC.

func InitPWM

func InitPWM()

InitPWM initializes the registers needed for PWM.

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

type ADC

type ADC struct {
	Pin Pin

func (ADC) Configure

func (a ADC) Configure(ADCConfig)

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

func (ADC) Get

func (a ADC) Get() uint16

Get returns the current value of a ADC pin in the range 0..0xffff.

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 *nrf.TWI_Type

I2C on the NRF.

func (I2C) Configure

func (i2c I2C) Configure(config I2CConfig) error

Configure is intended to setup the I2C interface.

func (I2C) ReadRegister

func (i2c I2C) ReadRegister(address uint8, register uint8, data []byte) error

ReadRegister transmits the register, restarts the connection as a read operation, and reads the response.

Many I2C-compatible devices are organized in terms of registers. This method is a shortcut to easily read such registers. Also, it only works for devices with 7-bit addresses, which is the vast majority.

func (I2C) Tx

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

Tx does a single I2C transaction at the specified address. It clocks out the given address, writes the bytes in w, reads back len® bytes and stores them in r, and generates a stop condition on the bus.

func (I2C) WriteRegister

func (i2c I2C) WriteRegister(address uint8, register uint8, data []byte) error

WriteRegister transmits first the register and then the data to the peripheral device.

Many I2C-compatible devices are organized in terms of registers. This method is a shortcut to easily write to such registers. Also, it only works for devices with 7-bit addresses, which is the vast majority.

type I2CConfig

type I2CConfig struct {
	Frequency	uint32
	SCL		Pin
	SDA		Pin

I2CConfig is used to store config info for I2C.

type PWM

type PWM struct {
	Pin Pin

func (PWM) Configure

func (pwm PWM) Configure()

Configure configures a PWM pin for output.

func (PWM) Set

func (pwm PWM) Set(value uint16)

Set turns on the duty cycle for a PWM pin using the provided value.

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.

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 port. This can be used to implement bit-banged drivers.

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.

func (Pin) Set

func (p Pin) Set(high bool)

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

func (Pin) SetInterrupt

func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error

SetInterrupt sets an interrupt to be executed when a particular pin changes state. The pin should already be configured as an input, including a pull up or down if no external pull is provided.

This call will replace a previously set callback on this pin. You can pass a nil func to unset the pin change interrupt. If you do so, the change parameter is ignored and can be set to any value (such as 0).

type PinChange

type PinChange uint8

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 https://www.embeddedrelated.com/showthread/comp.arch.embedded/77084-1.php

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 *nrf.SPIM_Type

SPI on the NRF.

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig)

Configure is intended to setup the SPI interface.

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. Therefore, if the number of bytes don’t match it will be padded until they fit: if len(w) > len® the extra bytes received will be dropped and if len(w) < len® extra 0 bytes will be sent.

type SPIConfig

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

SPIConfig is used to store config info for SPI.

type UART

type UART struct {
	Buffer *RingBuffer

UART on the NRF.

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 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) SetBaudRate

func (uart UART) SetBaudRate(br uint32)

SetBaudRate sets the communication speed for the UART.

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(c byte) error

WriteByte writes a byte of data to the UART.

type UARTConfig

type UARTConfig struct {
	BaudRate	uint32
	TX		Pin
	RX		Pin