trinket-m0

Constants

const (
	PA00	Pin	= 0	// peripherals: TCC2 channel 0
	PA01	Pin	= 1	// peripherals: TCC2 channel 1
	PA02	Pin	= 2
	PA03	Pin	= 3
	PA04	Pin	= 4	// peripherals: TCC0 channel 0
	PA05	Pin	= 5	// peripherals: TCC0 channel 1
	PA06	Pin	= 6	// peripherals: TCC1 channel 0
	PA07	Pin	= 7	// peripherals: TCC1 channel 1
	PA08	Pin	= 8	// peripherals: TCC0 channel 0, TCC1 channel 2
	PA09	Pin	= 9	// peripherals: TCC0 channel 1, TCC1 channel 3
	PA10	Pin	= 10	// peripherals: TCC1 channel 0, TCC0 channel 2
	PA11	Pin	= 11	// peripherals: TCC1 channel 1, TCC0 channel 3
	PA12	Pin	= 12	// peripherals: TCC2 channel 0, TCC0 channel 2
	PA13	Pin	= 13	// peripherals: TCC2 channel 1, TCC0 channel 3
	PA14	Pin	= 14	// peripherals: TCC0 channel 0
	PA15	Pin	= 15	// peripherals: TCC0 channel 1
	PA16	Pin	= 16	// peripherals: TCC2 channel 0, TCC0 channel 2
	PA17	Pin	= 17	// peripherals: TCC2 channel 1, TCC0 channel 3
	PA18	Pin	= 18	// peripherals: TCC0 channel 2
	PA19	Pin	= 19	// peripherals: TCC0 channel 3
	PA20	Pin	= 20	// peripherals: TCC0 channel 2
	PA21	Pin	= 21	// peripherals: TCC0 channel 3
	PA22	Pin	= 22	// peripherals: TCC0 channel 0
	PA23	Pin	= 23	// peripherals: TCC0 channel 1
	PA24	Pin	= 24	// peripherals: TCC1 channel 2
	PA25	Pin	= 25	// peripherals: TCC1 channel 3
	PA26	Pin	= 26
	PA27	Pin	= 27
	PA28	Pin	= 28
	PA29	Pin	= 29
	PA30	Pin	= 30	// peripherals: TCC1 channel 0
	PA31	Pin	= 31	// peripherals: TCC1 channel 1
	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	// peripherals: TCC0 channel 0
	PB11	Pin	= 43	// peripherals: TCC0 channel 1
	PB12	Pin	= 44	// peripherals: TCC0 channel 2
	PB13	Pin	= 45	// peripherals: TCC0 channel 3
	PB14	Pin	= 46
	PB15	Pin	= 47
	PB16	Pin	= 48	// peripherals: TCC0 channel 0
	PB17	Pin	= 49	// peripherals: TCC0 channel 1
	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	// peripherals: TCC0 channel 0, TCC1 channel 2
	PB31	Pin	= 63	// peripherals: TCC0 channel 1, TCC1 channel 3
)

Hardware pins

const (
	D0	= PA08	// PWM available
	D1	= PA02
	D2	= PA09	// PWM available
	D3	= PA07	// PWM available / UART0 RX
	D4	= PA06	// PWM available / UART0 TX
	D13	= PA10	// LED
)

GPIO Pins

const (
	A0	= D1
	A1	= D2
	A2	= D0
	A3	= D3
	A4	= D4
)

Analog pins

const (
	LED = D13
)
const (
	USBCDC_DM_PIN	= PA24
	USBCDC_DP_PIN	= PA25
)

USBCDC pins

const (
	UART_TX_PIN	= D4
	UART_RX_PIN	= D3
)

UART1 pins

const (
	SPI0_SCK_PIN	= D3
	SPI0_SDO_PIN	= D4
	SPI0_SDI_PIN	= D2
)

SPI pins

const (
	SDA_PIN	= D0	// SDA
	SCL_PIN	= D2	// SCL
)

I2C pins

const (
	I2S_SCK_PIN	= PA10
	I2S_SD_PIN	= PA08
	I2S_WS_PIN	= NoPin	// TODO: figure out what this is on Trinket M0.
)

I2S 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.

Deprecated: use 100 * machine.KHz or 400 * machine.KHz instead.

const (
	I2SModeSource	I2SMode	= iota
	I2SModeReceiver
	I2SModePDM
)
const (
	I2StandardPhilips	I2SStandard	= iota
	I2SStandardMSB
	I2SStandardLSB
)
const (
	I2SClockSourceInternal	I2SClockSource	= iota
	I2SClockSourceExternal
)
const (
	I2SDataFormatDefault	I2SDataFormat	= 0
	I2SDataFormat8bit			= 8
	I2SDataFormat16bit			= 16
	I2SDataFormat24bit			= 24
	I2SDataFormat32bit			= 32
)
const Device = deviceName

Device is the running program’s chip name, such as “ATSAMD51J19A” or “nrf52840”. It is not the same as the CPU name.

The constant is some hardcoded default value if the program does not target a particular chip but instead runs in WebAssembly for example.

const (
	KHz	= 1000
	MHz	= 1000_000
	GHz	= 1000_000_000
)

Generic constants.

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
	PinCom		PinMode	= 6
	//PinAC_CLK        PinMode = 7
	PinDigital		PinMode	= 8
	PinInput		PinMode	= 9
	PinInputPullup		PinMode	= 10
	PinOutput		PinMode	= 11
	PinTCC			PinMode	= PinTimer
	PinTCCAlt		PinMode	= PinTimerAlt
	PinInputPulldown	PinMode	= 12
)
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 (
	Mode0	= 0
	Mode1	= 1
	Mode2	= 2
	Mode3	= 3
)

SPI phase and polarity configs CPOL and CPHA

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

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

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

Variables

var UART1 = &sercomUSART0

UART1 on the Trinket M0.

var SPI0 = sercomSPIM0

SPI on the Trinket M0.

var (
	I2C0 = sercomI2CM2
)

I2C on the Trinket M0.

var (
	DefaultUART = UART1
)
var (
	ErrTimeoutRNG		= errors.New("machine: RNG Timeout")
	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 I2S0 = I2S{Bus: sam.I2S}
var (
	TCC0	= (*TCC)(sam.TCC0)
	TCC1	= (*TCC)(sam.TCC1)
	TCC2	= (*TCC)(sam.TCC2)
)

The SAM D21 has three TCC peripherals, which have PWM as one feature.

var (
	DAC0 = DAC{}
)
var (
	ErrPWMPeriodTooLong = errors.New("pwm: period too long")
)
var Serial Serialer

Serial is implemented via USB (USB-CDC).

var (
	ErrTxInvalidSliceSize		= errors.New("SPI write and read slices must be same size")
	errSPIInvalidMachineConfig	= errors.New("SPI port was not configured properly by the machine")
)
var (
	USBDev	= &USBDevice{}
	USBCDC	Serialer
)
var (
	ErrUSBReadTimeout	= errors.New("USB read timeout")
	ErrUSBBytesRead		= errors.New("USB invalid number of bytes read")
)

func CPUFrequency

func CPUFrequency() uint32

Return the current CPU frequency in hertz.

func EnableCDC

func EnableCDC(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool)

func EnableHID

func EnableHID(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool)

EnableHID enables HID. This function must be executed from the init().

func EnableMIDI

func EnableMIDI(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool)

EnableMIDI enables MIDI. This function must be executed from the init().

func EnterBootloader

func EnterBootloader()

EnterBootloader should perform a system reset in preperation to switch to the bootloader to flash new firmware.

func InitADC

func InitADC()

InitADC initializes the ADC.

func InitSerial

func InitSerial()

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

func ReceiveUSBControlPacket

func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error)

func SendUSBInPacket

func SendUSBInPacket(ep uint32, data []byte) bool

SendUSBInPacket sends a packet for USB (interrupt in / bulk in).

func SendZlp

func SendZlp()

type ADC

type ADC struct {
	Pin Pin
}

func (ADC) Configure

func (a ADC) Configure(config ADCConfig)

Configure configures a ADC pin 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 DAC

type DAC struct {
}

DAC on the SAMD21.

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 ATSAMD21 only has a 10-bit DAC, the passed-in value will be scaled down.

type DACConfig

type DACConfig struct {
}

DACConfig placeholder for future expansion.

type I2C

type I2C struct {
	Bus	*sam.SERCOM_I2CM_Type
	SERCOM	uint8
}

I2C on the SAMD21.

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 I2S

type I2S struct {
	Bus *sam.I2S_Type
}

I2S

func (I2S) Close

func (i2s I2S) Close() error

Close the I2S bus.

func (I2S) Configure

func (i2s I2S) Configure(config I2SConfig)

Configure is used to configure the I2S interface. You must call this before you can use the I2S bus.

func (I2S) Read

func (i2s I2S) Read(p []uint32) (n int, err error)

Read data from the I2S bus into the provided slice. The I2S bus must already have been configured correctly.

func (I2S) Write

func (i2s I2S) Write(p []uint32) (n int, err error)

Write data to the I2S bus from the provided slice. The I2S bus must already have been configured correctly.

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 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 when configured as an input or as an output.

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

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 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	*sam.SERCOM_SPI_Type
	SERCOM	uint8
}

SPI

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 Serialer

type Serialer interface {
	WriteByte(c byte) error
	Write(data []byte) (n int, err error)
	Configure(config UARTConfig) error
	Buffered() int
	ReadByte() (byte, error)
	DTR() bool
	RTS() bool
}

type TCC

type TCC sam.TCC_Type

TCC is one timer/counter 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 TCC 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 peripheral 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 Set (see Set documentation for more information).

type UART

type UART struct {
	Buffer		*RingBuffer
	Bus		*sam.SERCOM_USART_Type
	SERCOM		uint8
	Interrupt	interrupt.Interrupt
}

UART on the SAMD21.

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 uint8

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

type USBDevice

type USBDevice struct {
	initcomplete bool
}

func (*USBDevice) Configure

func (dev *USBDevice) Configure(config UARTConfig)

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