feather-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 = PA11 // UART0 RX
D1 = PA10 // UART0 TX
D2 = NoPin // does not seem to exist
D3 = PA09
D4 = PA08
D5 = PA15 // PWM available
D6 = PA20 // PWM available
D7 = NoPin // does not seem to exist
D8 = PA06
D9 = PA07 // PWM available
D10 = PA18 // can be used for PWM or UART1 TX
D11 = PA16 // can be used for PWM or UART1 RX
D12 = PA19 // PWM available
D13 = PA17 // PWM available
)
GPIO Pins
const (
A0 = PA02 // ADC/AIN[0]
A1 = PB08 // ADC/AIN[2]
A2 = PB09 // ADC/AIN[3]
A3 = PA04 // ADC/AIN[4]
A4 = PA05 // ADC/AIN[5]
A5 = PB02 // ADC/AIN[10]
)
Analog pins
const (
LED = D13
)
const (
USBCDC_DM_PIN = PA24
USBCDC_DP_PIN = PA25
)
USBCDC pins
const (
UART_TX_PIN = D10
UART_RX_PIN = D11
)
UART1 pins
const (
SDA_PIN = PA22 // SDA: SERCOM3/PAD[0]
SCL_PIN = PA23 // SCL: SERCOM3/PAD[1]
)
I2C pins
const (
SPI0_SCK_PIN = PB11 // SCK: SERCOM4/PAD[3]
SPI0_SDO_PIN = PB10 // SDO: SERCOM4/PAD[2]
SPI0_SDI_PIN = PA12 // SDI: SERCOM4/PAD[0]
)
SPI pins
const (
I2S_SCK_PIN = PA10
I2S_SD_PIN = PA08
I2S_WS_PIN = NoPin // TODO: figure out what this is on Feather 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 (
// I2CReceive indicates target has received a message from the controller.
I2CReceive I2CTargetEvent = iota
// I2CRequest indicates the controller is expecting a message from the target.
I2CRequest
// I2CFinish indicates the controller has ended the transaction.
//
// I2C controllers can chain multiple receive/request messages without
// relinquishing the bus by doing 'restarts'. I2CFinish indicates the
// bus has been relinquished by an I2C 'stop'.
I2CFinish
)
const (
// I2CModeController represents an I2C peripheral in controller mode.
I2CModeController I2CMode = iota
// I2CModeTarget represents an I2C peripheral in target mode.
I2CModeTarget
)
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 = &sercomUSART1
UART1 on the Feather M0.
var (
I2C0 = sercomI2CM3
)
I2C on the Feather M0.
var SPI0 = sercomSPIM4
SPI on the Feather M0.
var (
DefaultUART = UART1
)
var (
ErrTimeoutRNG = errors.New("machine: RNG Timeout")
ErrClockRNG = errors.New("machine: RNG Clock Error")
ErrSeedRNG = errors.New("machine: RNG Seed Error")
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 Flash flashBlockDevice
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")
ErrUSBBytesWritten = errors.New("USB invalid number of bytes written")
)
func CPUFrequency
func CPUFrequency() uint32
Return the current CPU frequency in hertz.
func CPUReset
func CPUReset()
CPUReset performs a hard system reset.
func ConfigureUSBEndpoint
func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointConfig, setup []usb.SetupConfig)
func DeviceID
func DeviceID() []byte
DeviceID returns an identifier that is unique within a particular chipset.
The identity is one burnt into the MCU itself, or the flash chip at time of manufacture.
It’s possible that two different vendors may allocate the same DeviceID, so callers should take this into account if needing to generate a globally unique id.
The length of the hardware ID is vendor-specific, but 8 bytes (64 bits) and 16 bytes (128 bits) are common.
func EnableCDC
func EnableCDC(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool)
func EnterBootloader
func EnterBootloader()
EnterBootloader should perform a system reset in preperation to switch to the bootloader to flash new firmware.
func FlashDataEnd
func FlashDataEnd() uintptr
Return the end of the writable flash area. Usually this is the address one past the end of the on-chip flash.
func FlashDataStart
func FlashDataStart() uintptr
Return the start of the writable flash area, aligned on a page boundary. This is usually just after the program and static data.
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)
SampleTime uint32 // sample time, in microseconds (µs)
}
ADCConfig holds ADC configuration parameters. If left unspecified, the zero value of each parameter will use the peripheral’s default settings.
type BlockDevice
type BlockDevice interface {
// ReadAt reads the given number of bytes from the block device.
io.ReaderAt
// WriteAt writes the given number of bytes to the block device.
io.WriterAt
// Size returns the number of bytes in this block device.
Size() int64
// WriteBlockSize returns the block size in which data can be written to
// memory. It can be used by a client to optimize writes, non-aligned writes
// should always work correctly.
WriteBlockSize() int64
// EraseBlockSize returns the smallest erasable area on this particular chip
// in bytes. This is used for the block size in EraseBlocks.
// It must be a power of two, and may be as small as 1. A typical size is 4096.
EraseBlockSize() int64
// EraseBlocks erases the given number of blocks. An implementation may
// transparently coalesce ranges of blocks into larger bundles if the chip
// supports this. The start and len parameters are in block numbers, use
// EraseBlockSize to map addresses to blocks.
EraseBlocks(start, len int64) error
}
BlockDevice is the raw device that is meant to store flash data.
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) error
SetBaudRate sets the communication speed for 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 I2CMode
type I2CMode int
I2CMode determines if an I2C peripheral is in Controller or Target mode.
type I2CTargetEvent
type I2CTargetEvent uint8
I2CTargetEvent reflects events on the I2C bus
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 PDMConfig
type PDMConfig struct {
Stereo bool
DIN Pin
CLK Pin
}
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 over the UART’s Tx. This function blocks until the data is finished being sent.
func (*UART) WriteByte
func (uart *UART) WriteByte(c byte) error
WriteByte writes a byte of data over the UART’s Tx. This function blocks until the data is finished being sent.
type UARTConfig
type UARTConfig struct {
BaudRate uint32
TX Pin
RX Pin
RTS Pin
CTS 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
InitEndpointComplete bool
}
func (*USBDevice) Configure
func (dev *USBDevice) Configure(config UARTConfig)
Configure the USB peripheral. The config is here for compatibility with the UART interface.