circuitplay-express
Constants
const ( PA00Pin= 0// peripherals: TCC2 channel 0, sercomI2CM1 SDA PA01Pin= 1// peripherals: TCC2 channel 1, sercomI2CM1 SCL PA02Pin= 2 PA03Pin= 3 PA04Pin= 4// peripherals: TCC0 channel 0 PA05Pin= 5// peripherals: TCC0 channel 1 PA06Pin= 6// peripherals: TCC1 channel 0 PA07Pin= 7// peripherals: TCC1 channel 1 PA08Pin= 8// peripherals: TCC0 channel 0, TCC1 channel 2, sercomI2CM0 SDA, sercomI2CM2 SDA PA09Pin= 9// peripherals: TCC0 channel 1, TCC1 channel 3, sercomI2CM0 SCL, sercomI2CM2 SCL PA10Pin= 10// peripherals: TCC1 channel 0, TCC0 channel 2 PA11Pin= 11// peripherals: TCC1 channel 1, TCC0 channel 3 PA12Pin= 12// peripherals: TCC2 channel 0, TCC0 channel 2, sercomI2CM2 SDA, sercomI2CM4 SDA PA13Pin= 13// peripherals: TCC2 channel 1, TCC0 channel 3, sercomI2CM2 SCL, sercomI2CM4 SCL PA14Pin= 14// peripherals: TCC0 channel 0 PA15Pin= 15// peripherals: TCC0 channel 1 PA16Pin= 16// peripherals: TCC2 channel 0, TCC0 channel 2, sercomI2CM1 SDA, sercomI2CM3 SDA PA17Pin= 17// peripherals: TCC2 channel 1, TCC0 channel 3, sercomI2CM1 SCL, sercomI2CM3 SCL PA18Pin= 18// peripherals: TCC0 channel 2 PA19Pin= 19// peripherals: TCC0 channel 3 PA20Pin= 20// peripherals: TCC0 channel 2 PA21Pin= 21// peripherals: TCC0 channel 3 PA22Pin= 22// peripherals: TCC0 channel 0, sercomI2CM3 SDA, sercomI2CM5 SDA PA23Pin= 23// peripherals: TCC0 channel 1, sercomI2CM3 SCL, sercomI2CM5 SCL PA24Pin= 24// peripherals: TCC1 channel 2 PA25Pin= 25// peripherals: TCC1 channel 3 PA26Pin= 26 PA27Pin= 27 PA28Pin= 28 PA29Pin= 29 PA30Pin= 30// peripherals: TCC1 channel 0 PA31Pin= 31// peripherals: TCC1 channel 1 PB00Pin= 32 PB01Pin= 33 PB02Pin= 34// peripherals: sercomI2CM5 SDA PB03Pin= 35// peripherals: sercomI2CM5 SCL PB04Pin= 36 PB05Pin= 37 PB06Pin= 38 PB07Pin= 39 PB08Pin= 40// peripherals: sercomI2CM4 SDA PB09Pin= 41// peripherals: sercomI2CM4 SCL PB10Pin= 42// peripherals: TCC0 channel 0 PB11Pin= 43// peripherals: TCC0 channel 1 PB12Pin= 44// peripherals: TCC0 channel 2, sercomI2CM4 SDA PB13Pin= 45// peripherals: TCC0 channel 3, sercomI2CM4 SCL PB14Pin= 46 PB15Pin= 47 PB16Pin= 48// peripherals: TCC0 channel 0, sercomI2CM5 SDA PB17Pin= 49// peripherals: TCC0 channel 1, sercomI2CM5 SCL PB18Pin= 50 PB19Pin= 51 PB20Pin= 52 PB21Pin= 53 PB22Pin= 54 PB23Pin= 55 PB24Pin= 56 PB25Pin= 57 PB26Pin= 58 PB27Pin= 59 PB28Pin= 60 PB29Pin= 61 PB30Pin= 62// peripherals: TCC0 channel 0, TCC1 channel 2, sercomI2CM5 SDA PB31Pin= 63// peripherals: TCC0 channel 1, TCC1 channel 3, sercomI2CM5 SCL ) Hardware pins
const ( D0= PB09 D1= PB08 D2= PB02 D3= PB03 D4= PA28 D5= PA14 D6= PA05 D7= PA15 D8= PB23 D9= PA06 D10= PA07 D11= NoPin// does not seem to exist D12= PA02 D13= PA17// PWM available ) GPIO Pins
const ( A0= PA02// ADC/AIN[0] A1= PA05// PWM available, also ADC/AIN[5] A2= PA06// PWM available, also ADC/AIN[6] A3= PA07// PWM available, also ADC/AIN[7] A4= PB03// PORTB A5= PB02// PORTB A6= PB09// PORTB A7= PB08// PORTB A8= PA11// ADC/AIN[19] A9= PA09// ADC/AIN[17] A10= PA04 ) Analog Pins
const ( LED= D13 NEOPIXELS= D8 WS2812= D8 BUTTONA= D4 BUTTONB= D5 SLIDER= D7// built-in slide switch BUTTON= BUTTONA BUTTON1= BUTTONB LIGHTSENSOR= A8 TEMPSENSOR= A9 PROXIMITY= A10 ) const ( USBCDC_DM_PIN= PA24 USBCDC_DP_PIN= PA25 ) USBCDC pins (logical UART0)
const ( UART_TX_PIN= PB08// PORTB UART_RX_PIN= PB09// PORTB ) UART0 pins (logical UART1)
const ( SDA_PIN= PB02// I2C0 external SCL_PIN= PB03// I2C0 external SDA1_PIN= PA00// I2C1 internal SCL1_PIN= PA01// I2C1 internal ) I2C pins
const ( SPI0_SCK_PIN= PA21// SCK: SERCOM3/PAD[3] SPI0_SDO_PIN= PA20// SDO: SERCOM3/PAD[2] SPI0_SDI_PIN= PA16// SDI: SERCOM3/PAD[0] ) SPI pins (internal flash)
const ( I2S_SCK_PIN= PA10 I2S_SDO_PIN= PA08 I2S_SDI_PIN= NoPin I2S_WS_PIN= NoPin// no WS, instead uses SCK to sync ) 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. I2CReceiveI2CTargetEvent= 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. I2CModeControllerI2CMode= iota // I2CModeTarget represents an I2C peripheral in target mode. I2CModeTarget ) const ( I2SModeSourceI2SMode= iota I2SModeReceiver I2SModePDM I2SModeSourceReceiver ) const ( I2StandardPhilipsI2SStandard= iota I2SStandardMSB I2SStandardLSB ) const ( I2SClockSourceInternalI2SClockSource= iota I2SClockSourceExternal ) const ( I2SDataFormatDefaultI2SDataFormat= 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 ( PinAnalogPinMode= 1 PinSERCOMPinMode= 2 PinSERCOMAltPinMode= 3 PinTimerPinMode= 4 PinTimerAltPinMode= 5 PinComPinMode= 6 //PinAC_CLK PinMode = 7 PinDigitalPinMode= 8 PinInputPinMode= 9 PinInputPullupPinMode= 10 PinOutputPinMode= 11 PinTCCPinMode= PinTimer PinTCCAltPinMode= PinTimerAlt PinInputPulldownPinMode= 12 ) const ( PinRisingPinChange= sam.EIC_CONFIG_SENSE0_RISE PinFallingPinChange= sam.EIC_CONFIG_SENSE0_FALL PinTogglePinChange= sam.EIC_CONFIG_SENSE0_BOTH ) Pin change interrupt constants for SetInterrupt.
const ( // WatchdogMaxTimeout in milliseconds (16s) WatchdogMaxTimeout = (16384 * 1000) / 1024 ) const ( // these are SAMD21 specific. usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos= 0 usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask= 0x3FFF usb_DEVICE_PCKSIZE_SIZE_Pos= 28 usb_DEVICE_PCKSIZE_SIZE_Mask= 0x7 usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Pos= 14 usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Mask= 0x3FFF NumberOfUSBEndpoints= 8 ) 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. ParityNoneUARTParity= 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= &sercomUSART4 DefaultUART= UART1 ) UART1 on the Circuit Playground Express.
var ( I2C0= sercomI2CM5// external device I2C1= sercomI2CM1// internal device ) I2C on the Circuit Playground Express.
var SPI0 = sercomSPIM3 SPI on the Circuit Playground Express.
var ( ErrInvalidSampleFrequency = errors.New("i2s: invalid sample frequency") ) 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 Watchdog = &watchdogImpl{} Watchdog provides access to the hardware watchdog available in the SAMD21.
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{} USBCDCSerialer ) 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 AckUsbOutTransfer
func AckUsbOutTransfer(ep uint32) AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
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 preparation 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 { Referenceuint32// analog reference voltage (AREF) in millivolts Resolutionuint32// number of bits for a single conversion (e.g., 8, 10, 12) Samplesuint32// number of samples for a single conversion (e.g., 4, 8, 16, 32) SampleTimeuint32// 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 SERCOMuint8 } 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 { Frequencyuint32 SCLPin SDAPin } 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 Frequencyuint32 DataFormatI2SDataFormat } I2S
func (*I2S) Configure
func (i2s *I2S) Configure(config I2SConfig) error Configure is used to configure the I2S interface. You must call this before you can use the I2S bus.
func (*I2S) Enable
func (i2s *I2S) Enable(enabled bool) Enabled is used to enable or disable the I2S bus.
func (*I2S) ReadMono
func (i2s *I2S) ReadMono(p []uint16) (n int, err error) Read mono data from the I2S bus into the provided slice. The I2S bus must already have been configured correctly.
func (*I2S) ReadStereo
func (i2s *I2S) ReadStereo(p []uint32) (n int, err error) Read stereo data from the I2S bus into the provided slice. The I2S bus must already have been configured correctly.
func (*I2S) SetSampleFrequency
func (i2s *I2S) SetSampleFrequency(freq uint32) error SetSampleFrequency is used to set the sample frequency for the I2S bus.
func (*I2S) WriteMono
func (i2s *I2S) WriteMono(p []uint16) (n int, err error) Write mono data to the I2S bus from the provided slice. The I2S bus must already have been configured correctly.
func (*I2S) WriteStereo
func (i2s *I2S) WriteStereo(p []uint32) (n int, err error) Write stereo 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 { // clock SCKPin // word select WSPin // data out SDOPin // data in SDIPin ModeI2SMode StandardI2SStandard ClockSourceI2SClockSource DataFormatI2SDataFormat AudioFrequencyuint32 MainClockOutputbool Stereobool } 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 { Stereobool DINPin CLKPin } 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 headvolatile.Register8 tailvolatile.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 SERCOMuint8 } 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 synchronous 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 { Frequencyuint32 SCKPin SDOPin SDIPin LSBFirstbool Modeuint8 } 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 SERCOMuint8 Interruptinterrupt.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 { BaudRateuint32 TXPin RXPin RTSPin CTSPin } 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 { initcompletebool InitEndpointCompletebool } func (*USBDevice) Configure
func (dev *USBDevice) Configure(config UARTConfig) Configure the USB peripheral. The config is here for compatibility with the UART interface.
type WatchdogConfig
type WatchdogConfig struct { // The timeout (in milliseconds) before the watchdog fires. // // If the requested timeout exceeds `MaxTimeout` it will be rounded // down. TimeoutMillis uint32 } WatchdogConfig holds configuration for the watchdog timer.