const RESET_MAGIC_VALUE = 0xf01669ef

used to reset into bootloader

const (
	D0	= PB17	// UART0 RX/PWM available
	D1	= PB16	// UART0 TX/PWM available
	D2	= PB03
	D3	= PB02
	D4	= PA14	// PWM available
	D5	= PA16	// PWM available
	D6	= PA18	// PWM available
	D7	= PB14
	D8	= PA15	// built-in neopixel
	D9	= PA19	// PWM available
	D10	= PA20	// can be used for PWM or UART1 TX
	D11	= PA21	// can be used for PWM or UART1 RX
	D12	= PA22	// PWM available
	D13	= PA23	// PWM available


const (
	A0	= PA02	// ADC/AIN[0]
	A1	= PA05	// ADC/AIN[2]
	A2	= PB08	// ADC/AIN[3]
	A3	= PB09	// ADC/AIN[4]
	A4	= PA04	// ADC/AIN[5]
	A5	= PA06	// ADC/AIN[6]
	A6	= PB01	// ADC/AIN[12]/VMEAS
	A7	= PB04	// ADC/AIN[6]/LIGHT
	A8	= D2	// ADC/AIN[14]
	A9	= D3	// ADC/AIN[15]

Analog pins

const (
	LED		= D13
	WS2812		= D8



	TFT_DC		= PB05
	TFT_CS		= PB07
	TFT_RST		= PA00

const (
const (


const (

UART1 pins

const (
const (

I2C pins

const (

SPI pins

const (

TFT SPI 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 (
	I2SModeSource	I2SMode	= iota
const (
	I2StandardPhilips	I2SStandard	= iota
const (
	I2SClockSourceInternal	I2SClockSource	= iota
const (
	I2SDataFormatDefault	I2SDataFormat	= 0
	I2SDataFormat8bit			= 8
	I2SDataFormat16bit			= 16
	I2SDataFormat24bit			= 24
	I2SDataFormat32bit			= 32
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 (
	PinAnalog		PinMode	= 1
	PinSERCOM		PinMode	= 2
	PinSERCOMAlt		PinMode	= 3
	PinTimer		PinMode	= 4
	PinTimerAlt		PinMode	= 5
	PinTCCPDEC		PinMode	= 6
	PinCom			PinMode	= 7
	PinSDHC			PinMode	= 8
	PinI2S			PinMode	= 9
	PinPCC			PinMode	= 10
	PinGMAC			PinMode	= 11
	PinACCLK		PinMode	= 12
	PinCCL			PinMode	= 13
	PinDigital		PinMode	= 14
	PinInput		PinMode	= 15
	PinInputPullup		PinMode	= 16
	PinOutput		PinMode	= 17
	PinTCCE			PinMode	= PinTimer
	PinTCCF			PinMode	= PinTimerAlt
	PinTCCG			PinMode	= PinTCCPDEC
	PinInputPulldown	PinMode	= 18
	PinCAN			PinMode	= 19
	PinCAN0			PinMode	= PinSDHC
	PinCAN1			PinMode	= PinCom
const (
	PinRising	PinChange	= sam.EIC_CONFIG_SENSE0_RISE
	PinFalling	PinChange	= sam.EIC_CONFIG_SENSE0_FALL
	PinToggle	PinChange	= sam.EIC_CONFIG_SENSE0_BOTH

Pin change interrupt constants for SetInterrupt.

const (
	PA00	Pin	= 0
	PA01	Pin	= 1
	PA02	Pin	= 2
	PA03	Pin	= 3
	PA04	Pin	= 4
	PA05	Pin	= 5
	PA06	Pin	= 6
	PA07	Pin	= 7
	PA08	Pin	= 8
	PA09	Pin	= 9
	PA10	Pin	= 10
	PA11	Pin	= 11
	PA12	Pin	= 12
	PA13	Pin	= 13
	PA14	Pin	= 14
	PA15	Pin	= 15
	PA16	Pin	= 16
	PA17	Pin	= 17
	PA18	Pin	= 18
	PA19	Pin	= 19
	PA20	Pin	= 20
	PA21	Pin	= 21
	PA22	Pin	= 22
	PA23	Pin	= 23
	PA24	Pin	= 24
	PA25	Pin	= 25
	PA26	Pin	= 26
	PA27	Pin	= 27
	PA28	Pin	= 28
	PA29	Pin	= 29
	PA30	Pin	= 30
	PA31	Pin	= 31
	PB00	Pin	= 32
	PB01	Pin	= 33
	PB02	Pin	= 34
	PB03	Pin	= 35
	PB04	Pin	= 36
	PB05	Pin	= 37
	PB06	Pin	= 38
	PB07	Pin	= 39
	PB08	Pin	= 40
	PB09	Pin	= 41
	PB10	Pin	= 42
	PB11	Pin	= 43
	PB12	Pin	= 44
	PB13	Pin	= 45
	PB14	Pin	= 46
	PB15	Pin	= 47
	PB16	Pin	= 48
	PB17	Pin	= 49
	PB18	Pin	= 50
	PB19	Pin	= 51
	PB20	Pin	= 52
	PB21	Pin	= 53
	PB22	Pin	= 54
	PB23	Pin	= 55
	PB24	Pin	= 56
	PB25	Pin	= 57
	PB26	Pin	= 58
	PB27	Pin	= 59
	PB28	Pin	= 60
	PB29	Pin	= 61
	PB30	Pin	= 62
	PB31	Pin	= 63
	PC00	Pin	= 64
	PC01	Pin	= 65
	PC02	Pin	= 66
	PC03	Pin	= 67
	PC04	Pin	= 68
	PC05	Pin	= 69
	PC06	Pin	= 70
	PC07	Pin	= 71
	PC08	Pin	= 72
	PC09	Pin	= 73
	PC10	Pin	= 74
	PC11	Pin	= 75
	PC12	Pin	= 76
	PC13	Pin	= 77
	PC14	Pin	= 78
	PC15	Pin	= 79
	PC16	Pin	= 80
	PC17	Pin	= 81
	PC18	Pin	= 82
	PC19	Pin	= 83
	PC20	Pin	= 84
	PC21	Pin	= 85
	PC22	Pin	= 86
	PC23	Pin	= 87
	PC24	Pin	= 88
	PC25	Pin	= 89
	PC26	Pin	= 90
	PC27	Pin	= 91
	PC28	Pin	= 92
	PC29	Pin	= 93
	PC30	Pin	= 94
	PC31	Pin	= 95
	PD00	Pin	= 96
	PD01	Pin	= 97
	PD02	Pin	= 98
	PD03	Pin	= 99
	PD04	Pin	= 100
	PD05	Pin	= 101
	PD06	Pin	= 102
	PD07	Pin	= 103
	PD08	Pin	= 104
	PD09	Pin	= 105
	PD10	Pin	= 106
	PD11	Pin	= 107
	PD12	Pin	= 108
	PD13	Pin	= 109
	PD14	Pin	= 110
	PD15	Pin	= 111
	PD16	Pin	= 112
	PD17	Pin	= 113
	PD18	Pin	= 114
	PD19	Pin	= 115
	PD20	Pin	= 116
	PD21	Pin	= 117
	PD22	Pin	= 118
	PD23	Pin	= 119
	PD24	Pin	= 120
	PD25	Pin	= 121
	PD26	Pin	= 122
	PD27	Pin	= 123
	PD28	Pin	= 124
	PD29	Pin	= 125
	PD30	Pin	= 126
	PD31	Pin	= 127

Hardware pins

const (
	// SERCOM_FREQ_REF is always reference frequency on SAMD51 regardless of CPU speed.
	SERCOM_FREQ_REF	= 48000000

	// Default rise time in nanoseconds, based on 4.7K ohm pull up resistors
	riseTimeNanoseconds	= 125

	// wire bus states
	wireUnknownState	= 0
	wireIdleState		= 1
	wireOwnerState		= 2
	wireBusyState		= 3

	// wire commands
	wireCmdNoAction		= 0
	wireCmdRepeatStart	= 1
	wireCmdRead		= 2
	wireCmdStop		= 3
const (
	QSPI_CS		= PB11

The QSPI peripheral on ATSAMD51 is only available on the following pins

const HSRAM_SIZE = 0x00030000
const (
	// ParityNone means to not use any parity checking. This is
	// the most common setting.
	ParityNone	UARTParity	= 0

	// ParityEven means to expect that the total number of 1 bits sent
	// should be an even number.
	ParityEven	UARTParity	= 1

	// ParityOdd means to expect that the total number of 1 bits sent
	// should be an odd number.
	ParityOdd	UARTParity	= 2


var (
	UART1	= &_UART1
		Buffer:	NewRingBuffer(),
		SERCOM:	5,

	UART2	= &_UART2
		Buffer:	NewRingBuffer(),
		SERCOM:	0,
var (
	I2C0 = &I2C{
		Bus:	sam.SERCOM2_I2CM,
		SERCOM:	2,

I2C on the ItsyBitsy M4.

var (
	SPI0 = SPI{
		Bus:	sam.SERCOM1_SPIM,
		SERCOM:	1,

SPI on the PyBadge.

var (
	SPI1 = SPI{
		Bus:	sam.SERCOM4_SPIM,
		SERCOM:	4,

TFT SPI on the PyBadge.

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 (
	// USB is a USB CDC interface.
	USB = &USBCDC{Buffer: NewRingBuffer()}
var (
	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
var (
	DAC0 = DAC{}
var (
	TCC0	= (*TCC)(sam.TCC0)
	TCC1	= (*TCC)(sam.TCC1)
	TCC2	= (*TCC)(sam.TCC2)
	TCC3	= (*TCC)(sam.TCC3)
	TCC4	= (*TCC)(sam.TCC4)

This chip has five TCC peripherals, which have PWM as one feature.

var (
	ErrPWMPeriodTooLong = errors.New("pwm: period too long")
var Serial = USB

Serial is implemented via USB (USB-CDC).

func CPUFrequency

func CPUFrequency() uint32

func InitADC

func InitADC()

InitADC initializes the ADC.

func NewACMFunctionalDescriptor

func NewACMFunctionalDescriptor(subtype, d0 uint8) ACMFunctionalDescriptor

NewACMFunctionalDescriptor returns a new USB ACMFunctionalDescriptor.

func NewCDCCSInterfaceDescriptor

func NewCDCCSInterfaceDescriptor(subtype, d0, d1 uint8) CDCCSInterfaceDescriptor

NewCDCCSInterfaceDescriptor returns a new USB CDCCSInterfaceDescriptor.

func NewCDCDescriptor

func NewCDCDescriptor(i IADDescriptor, c InterfaceDescriptor,
	h CDCCSInterfaceDescriptor,
	cm ACMFunctionalDescriptor,
	fd CDCCSInterfaceDescriptor,
	callm CMFunctionalDescriptor,
	ci EndpointDescriptor,
	di InterfaceDescriptor,
	outp EndpointDescriptor,
	inp EndpointDescriptor) CDCDescriptor

func NewCMFunctionalDescriptor

func NewCMFunctionalDescriptor(subtype, d0, d1 uint8) CMFunctionalDescriptor

NewCMFunctionalDescriptor returns a new USB CMFunctionalDescriptor.

func NewConfigDescriptor

func NewConfigDescriptor(totalLength uint16, interfaces uint8) ConfigDescriptor

NewConfigDescriptor returns a new USB ConfigDescriptor.

func NewDeviceDescriptor

func NewDeviceDescriptor(class, subClass, proto, packetSize0 uint8, vid, pid, version uint16, im, ip, is, configs uint8) DeviceDescriptor

NewDeviceDescriptor returns a USB DeviceDescriptor.

func NewEndpointDescriptor

func NewEndpointDescriptor(addr, attr uint8, packetSize uint16, interval uint8) EndpointDescriptor

NewEndpointDescriptor returns a new USB EndpointDescriptor.

func NewIADDescriptor

func NewIADDescriptor(firstInterface, count, class, subClass, protocol uint8) IADDescriptor

NewIADDescriptor returns a new USB IADDescriptor.

func NewInterfaceDescriptor

func NewInterfaceDescriptor(n, numEndpoints, class, subClass, protocol uint8) InterfaceDescriptor

NewInterfaceDescriptor returns a new USB InterfaceDescriptor.

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

func ResetProcessor

func ResetProcessor()

ResetProcessor should perform a system reset in preparation to switch to the bootloader to flash new firmware.

type ACMFunctionalDescriptor

type ACMFunctionalDescriptor struct {
	len		uint8
	dtype		uint8	// 0x24
	subtype		uint8	// 1
	bmCapabilities	uint8

ACMFunctionalDescriptor is a Abstract Control Model (ACM) USB descriptor.

func (ACMFunctionalDescriptor) Bytes

func (d ACMFunctionalDescriptor) Bytes() [acmFunctionalDescriptorSize]byte

Bytes returns the ACMFunctionalDescriptor data.

type ADC

type ADC struct {
	Pin Pin

func (ADC) Configure

func (a ADC) Configure(config ADCConfig)

Configure configures a ADCPin to be able to be used to read 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 CDCCSInterfaceDescriptor

type CDCCSInterfaceDescriptor struct {
	len	uint8	// 5
	dtype	uint8	// 0x24
	subtype	uint8
	d0	uint8
	d1	uint8

CDCCSInterfaceDescriptor is a CDC CS interface descriptor.

func (CDCCSInterfaceDescriptor) Bytes

func (d CDCCSInterfaceDescriptor) Bytes() [cdcCSInterfaceDescriptorSize]byte

Bytes returns CDCCSInterfaceDescriptor data.

type CDCDescriptor

type CDCDescriptor struct {
	//	IAD
	iad	IADDescriptor	// Only needed on compound device

	//	Control
	cif	InterfaceDescriptor
	header	CDCCSInterfaceDescriptor

	// CDC control
	controlManagement	ACMFunctionalDescriptor		// ACM
	functionalDescriptor	CDCCSInterfaceDescriptor	// CDC_UNION
	callManagement		CMFunctionalDescriptor		// Call Management
	cifin			EndpointDescriptor

	//	CDC Data
	dif	InterfaceDescriptor
	in	EndpointDescriptor
	out	EndpointDescriptor

CDCDescriptor is the Communication Device Class (CDC) descriptor.

func (CDCDescriptor) Bytes

func (d CDCDescriptor) Bytes() [cdcSize]byte

Bytes returns CDCDescriptor data.

type CMFunctionalDescriptor

type CMFunctionalDescriptor struct {
	bFunctionLength		uint8
	bDescriptorType		uint8	// 0x24
	bDescriptorSubtype	uint8	// 1
	bmCapabilities		uint8
	bDataInterface		uint8

CMFunctionalDescriptor is the functional descriptor general format.

func (CMFunctionalDescriptor) Bytes

func (d CMFunctionalDescriptor) Bytes() [cmFunctionalDescriptorSize]byte

Bytes returns the CMFunctionalDescriptor data.

type ConfigDescriptor

type ConfigDescriptor struct {
	bLength			uint8	// 9
	bDescriptorType		uint8	// 2
	wTotalLength		uint16	// total length
	bNumInterfaces		uint8
	bConfigurationValue	uint8
	iConfiguration		uint8
	bmAttributes		uint8
	bMaxPower		uint8

ConfigDescriptor implements the standard USB configuration descriptor.

Table 9-10. Standard Configuration Descriptor bLength, bDescriptorType, wTotalLength, bNumInterfaces, bConfigurationValue, iConfiguration bmAttributes, bMaxPower

func (ConfigDescriptor) Bytes

func (d ConfigDescriptor) Bytes() [configDescriptorSize]byte

Bytes returns ConfigDescriptor data.

type DAC

type DAC struct {

DAC on the SAMD51.

func (DAC) Configure

func (dac DAC) Configure(config DACConfig)

Configure the DAC. output pin must already be configured.

func (DAC) Set

func (dac DAC) Set(value uint16) error

Set writes a single 16-bit value to the DAC. Since the ATSAMD51 only has a 12-bit DAC, the passed-in value will be scaled down.

type DACConfig

type DACConfig struct {

DACConfig placeholder for future expansion.

type DeviceDescriptor

type DeviceDescriptor struct {
	bLength			uint8	// 18
	bDescriptorType		uint8	// 1 USB_DEVICE_DESCRIPTOR_TYPE
	bcdUSB			uint16	// 0x200
	bDeviceClass		uint8
	bDeviceSubClass		uint8
	bDeviceProtocol		uint8
	bMaxPacketSize0		uint8	// Packet 0
	idVendor		uint16
	idProduct		uint16
	bcdDevice		uint16	// 0x100
	iManufacturer		uint8
	iProduct		uint8
	iSerialNumber		uint8
	bNumConfigurations	uint8

DeviceDescriptor implements the USB standard device descriptor.

Table 9-8. Standard Device Descriptor bLength, bDescriptorType, bcdUSB, bDeviceClass, bDeviceSubClass, bDeviceProtocol, bMaxPacketSize0, idVendor, idProduct, bcdDevice, iManufacturer, iProduct, iSerialNumber, bNumConfigurations */

func (DeviceDescriptor) Bytes

func (d DeviceDescriptor) Bytes() [deviceDescriptorSize]byte

Bytes returns DeviceDescriptor data

type EndpointDescriptor

type EndpointDescriptor struct {
	bLength			uint8	// 7
	bDescriptorType		uint8	// 5
	bEndpointAddress	uint8
	bmAttributes		uint8
	wMaxPacketSize		uint16
	bInterval		uint8

EndpointDescriptor implements the standard USB endpoint descriptor.

Table 9-13. Standard Endpoint Descriptor bLength, bDescriptorType, bEndpointAddress, bmAttributes, wMaxPacketSize, bInterval

func (EndpointDescriptor) Bytes

func (d EndpointDescriptor) Bytes() [endpointDescriptorSize]byte

Bytes returns EndpointDescriptor data.

type I2C

type I2C struct {
	Bus	*sam.SERCOM_I2CM_Type
	SERCOM	uint8

I2C on the SAMD51.

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) SetBaudRate

func (i2c *I2C) SetBaudRate(br uint32)

SetBaudRate sets the communication speed for the I2C.

func (*I2C) Tx

func (i2c *I2C) Tx(addr uint16, w, r []byte) 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(r) bytes and stores them in r, and generates a stop condition on the bus.

func (*I2C) WriteByte

func (i2c *I2C) WriteByte(data byte) error

WriteByte writes a single byte to the I2C 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 I2SClockSource

type I2SClockSource uint8

type I2SConfig

type I2SConfig struct {
	SCK		Pin
	WS		Pin
	SD		Pin
	Mode		I2SMode
	Standard	I2SStandard
	ClockSource	I2SClockSource
	DataFormat	I2SDataFormat
	AudioFrequency	uint32
	MainClockOutput	bool
	Stereo		bool

All fields are optional and may not be required or used on a particular platform.

type I2SDataFormat

type I2SDataFormat uint8

type I2SMode

type I2SMode uint8

type I2SStandard

type I2SStandard uint8

type IADDescriptor

type IADDescriptor struct {
	bLength			uint8	// 8
	bDescriptorType		uint8	// 11
	bFirstInterface		uint8
	bInterfaceCount		uint8
	bFunctionClass		uint8
	bFunctionSubClass	uint8
	bFunctionProtocol	uint8
	iFunction		uint8

IADDescriptor is an Interface Association Descriptor, which is used to bind 2 interfaces together in CDC composite device.

Standard Interface Association Descriptor: bLength, bDescriptorType, bFirstInterface, bInterfaceCount, bFunctionClass, bFunctionSubClass, bFunctionProtocol, iFunction

func (IADDescriptor) Bytes

func (d IADDescriptor) Bytes() [iadDescriptorSize]byte

Bytes returns IADDescriptor data.

type InterfaceDescriptor

type InterfaceDescriptor struct {
	bLength			uint8	// 9
	bDescriptorType		uint8	// 4
	bInterfaceNumber	uint8
	bAlternateSetting	uint8
	bNumEndpoints		uint8
	bInterfaceClass		uint8
	bInterfaceSubClass	uint8
	bInterfaceProtocol	uint8
	iInterface		uint8

InterfaceDescriptor implements the standard USB interface descriptor.

Table 9-12. Standard Interface Descriptor bLength, bDescriptorType, bInterfaceNumber, bAlternateSetting, bNumEndpoints, bInterfaceClass, bInterfaceSubClass, bInterfaceProtocol, iInterface

func (InterfaceDescriptor) Bytes

func (d InterfaceDescriptor) Bytes() [interfaceDescriptorSize]byte

Bytes returns InterfaceDescriptor data.

type MSCDescriptor

type MSCDescriptor struct {
	msc	InterfaceDescriptor
	in	EndpointDescriptor
	out	EndpointDescriptor

MSCDescriptor is not used yet.

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)

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).

func (Pin) Toggle

func (p Pin) Toggle()

Toggle switches an output pin from low to high or from high to low. Warning: only use this on an output pin!

type PinChange

type PinChange uint8

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.

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	*sam.SERCOM_SPIM_Type
	SERCOM	uint8


func (SPI) Configure

func (spi SPI) Configure(config SPIConfig) error

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. 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
	LSBFirst	bool
	Mode		uint8

SPIConfig is used to store config info for SPI.

type TCC

type TCC sam.TCC_Type

TCC is one timer peripheral, which consists of a counter and multiple output channels (that can be connected to actual pins). You can set the frequency using SetPeriod, but only for all the channels in this timer peripheral at once.

func (*TCC) Channel

func (tcc *TCC) Channel(pin Pin) (uint8, error)

Channel returns a PWM channel for the given pin. Note that one channel may be shared between multiple pins, and so will have the same duty cycle. If this is not desirable, look for a different TCC or consider using a different pin.

func (*TCC) Configure

func (tcc *TCC) Configure(config PWMConfig) error

Configure enables and configures this TCC.

func (*TCC) Counter

func (tcc *TCC) Counter() uint32

Counter returns the current counter value of the timer in this TCC peripheral. It may be useful for debugging.

func (*TCC) Set

func (tcc *TCC) Set(channel uint8, value uint32)

Set updates the channel value. This is used to control the channel duty cycle, in other words the fraction of time the channel output is high (or low when inverted). For example, to set it to a 25% duty cycle, use:

tcc.Set(channel, tcc.Top() / 4)

tcc.Set(channel, 0) will set the output to low and tcc.Set(channel, tcc.Top()) will set the output to high, assuming the output isn’t inverted.

func (*TCC) SetInverting

func (tcc *TCC) SetInverting(channel uint8, inverting bool)

SetInverting sets whether to invert the output of this channel. Without inverting, a 25% duty cycle would mean the output is high for 25% of the time and low for the rest. Inverting flips the output as if a NOT gate was placed at the output, meaning that the output would be 25% low and 75% high with a duty cycle of 25%.

func (*TCC) SetPeriod

func (tcc *TCC) SetPeriod(period uint64) error

SetPeriod updates the period of this TCC peripheral. To set a particular frequency, use the following formula:

period = 1e9 / frequency

If you use a period of 0, a period that works well for LEDs will be picked.

SetPeriod will not change the prescaler, but also won’t change the current value in any of the channels. This means that you may need to update the value for the particular channel.

Note that you cannot pick any arbitrary period after the TCC peripheral has been configured. If you want to switch between frequencies, pick the lowest frequency (longest period) once when calling Configure and adjust the frequency here as needed.

func (*TCC) Top

func (tcc *TCC) Top() uint32

Top returns the current counter top, for use in duty cycle calculation. It will only change with a call to Configure or SetPeriod, otherwise it is constant.

The value returned here is hardware dependent. In general, it’s best to treat it as an opaque value that can be divided by some number and passed to tcc.Set (see tcc.Set for more information).

type UART

type UART struct {
	Buffer		*RingBuffer
	Bus		*sam.SERCOM_USART_INT_Type
	SERCOM		uint8
	Interrupt	interrupt.Interrupt	// RXC interrupt

UART on the SAMD51.

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) error

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

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.

type UARTParity

type UARTParity int

UARTParity is the parity setting to be used for UART communication.


type USBCDC struct {
	Buffer			*RingBuffer
	TxIdx			volatile.Register8
	waitTxc			bool
	waitTxcRetryCount	uint8
	sent			bool

USBCDC is the USB CDC aka serial over USB interface on the SAMD21.

func (*USBCDC) Buffered

func (usbcdc *USBCDC) Buffered() int

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

func (*USBCDC) Configure

func (usbcdc *USBCDC) Configure(config UARTConfig)

Configure the USB CDC interface. The config is here for compatibility with the UART interface.

func (*USBCDC) DTR

func (usbcdc *USBCDC) DTR() bool

func (*USBCDC) Flush

func (usbcdc *USBCDC) Flush() error

Flush flushes buffered data.

func (*USBCDC) RTS

func (usbcdc *USBCDC) RTS() bool

func (*USBCDC) Read

func (usbcdc *USBCDC) Read(data []byte) (n int, err error)

Read from the RX buffer.

func (*USBCDC) ReadByte

func (usbcdc *USBCDC) ReadByte() (byte, error)

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

func (*USBCDC) Receive

func (usbcdc *USBCDC) Receive(data byte)

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

func (*USBCDC) Write

func (usbcdc *USBCDC) Write(data []byte) (n int, err error)

Write data to the USBCDC.

func (*USBCDC) WriteByte

func (usbcdc *USBCDC) WriteByte(c byte) error

WriteByte writes a byte of data to the USB CDC interface.