arduino-nano
Constants
const (
D0 = PD0 // RX0
D1 = PD1 // TX1
D2 = PD2
D3 = PD3
D4 = PD4
D5 = PD5
D6 = PD6
D7 = PD7
D8 = PB0
D9 = PB1
D10 = PB2
D11 = PB3
D12 = PB4
D13 = PB5
)
Digital pins.
const LED Pin = D13
LED on the Arduino
const (
ADC0 Pin = PC0
ADC1 Pin = PC1
ADC2 Pin = PC2
ADC3 Pin = PC3
ADC4 Pin = PC4 // Used by TWI for SDA
ADC5 Pin = PC5 // Used by TWI for SCL
)
ADC on the Arduino
const (
UART_TX_PIN Pin = PD1
UART_RX_PIN Pin = PD0
)
UART pins
const (
PB0 = portB + 0
PB1 = portB + 1 // peripherals: Timer1 channel A
PB2 = portB + 2 // peripherals: Timer1 channel B
PB3 = portB + 3 // peripherals: Timer2 channel A
PB4 = portB + 4
PB5 = portB + 5
PB6 = portB + 6
PB7 = portB + 7
PC0 = portC + 0
PC1 = portC + 1
PC2 = portC + 2
PC3 = portC + 3
PC4 = portC + 4
PC5 = portC + 5
PC6 = portC + 6
PC7 = portC + 7
PD0 = portD + 0
PD1 = portD + 1
PD2 = portD + 2
PD3 = portD + 3 // peripherals: Timer2 channel B
PD4 = portD + 4
PD5 = portD + 5 // peripherals: Timer0 channel B
PD6 = portD + 6 // peripherals: Timer0 channel A
PD7 = portD + 7
)
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 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 (
PinRising PinChange = 1 << iota
PinFalling
PinToggle = PinRising | PinFalling
)
const (
PinInput PinMode = iota
PinInputPullup
PinOutput
)
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 (
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 DefaultUART = UART0
Always use UART0 as the serial output.
var (
// UART0 is the hardware serial port on the AVR.
UART0 = &_UART0
_UART0 = UART{
Buffer: NewRingBuffer(),
dataReg: avr.UDR0,
baudRegH: avr.UBRR0H,
baudRegL: avr.UBRR0L,
statusRegA: avr.UCSR0A,
statusRegB: avr.UCSR0B,
statusRegC: avr.UCSR0C,
}
)
UART
var (
Timer0 = PWM{0} // 8 bit timer for PD5 and PD6
Timer1 = PWM{1} // 16 bit timer for PB1 and PB2
Timer2 = PWM{2} // 8 bit timer for PB3 and PD3
)
var I2C0 = &I2C{
srReg: avr.TWSR,
brReg: avr.TWBR,
crReg: avr.TWCR,
drReg: avr.TWDR,
srPS0: avr.TWSR_TWPS0,
srPS1: avr.TWSR_TWPS1,
crEN: avr.TWCR_TWEN,
crINT: avr.TWCR_TWINT,
crSTO: avr.TWCR_TWSTO,
crEA: avr.TWCR_TWEA,
crSTA: avr.TWCR_TWSTA,
}
I2C0 is the only I2C interface on most AVRs.
var SPI0 = SPI{
spcr: avr.SPCR,
spdr: avr.SPDR,
spsr: avr.SPSR,
spcrR0: avr.SPCR_SPR0,
spcrR1: avr.SPCR_SPR1,
spcrCPHA: avr.SPCR_CPHA,
spcrCPOL: avr.SPCR_CPOL,
spcrDORD: avr.SPCR_DORD,
spcrSPE: avr.SPCR_SPE,
spcrMSTR: avr.SPCR_MSTR,
spsrI2X: avr.SPSR_SPI2X,
spsrSPIF: avr.SPSR_SPIF,
sck: PB5,
sdo: PB3,
sdi: PB4,
cs: PB2,
}
SPI configuration
var (
ErrPWMPeriodTooLong = errors.New("pwm: period too long")
)
var Serial = DefaultUART
Serial is implemented via the default (usually the first) UART on the chip.
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")
)
func CPUFrequency
func CPUFrequency() uint32
Return the current CPU frequency in hertz.
func InitADC
func InitADC()
InitADC initializes the registers needed for ADC.
func InitSerial
func InitSerial()
func NewRingBuffer
func NewRingBuffer() *RingBuffer
NewRingBuffer returns a new ring buffer.
type ADC
type ADC struct {
Pin Pin
}
func (ADC) Configure
func (a ADC) Configure(ADCConfig)
Configure configures 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. The AVR has an ADC of 10 bits precision so the lower 6 bits will be zero.
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 I2C
type I2C struct {
srReg *volatile.Register8
brReg *volatile.Register8
crReg *volatile.Register8
drReg *volatile.Register8
srPS0 byte
srPS1 byte
crEN byte
crINT byte
crSTO byte
crEA byte
crSTA byte
}
I2C on AVR.
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) 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
}
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 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 PWM
type PWM struct {
num uint8
}
PWM is one PWM peripheral, which consists of a counter and two output channels (that can be connected to two fixed pins). You can set the frequency using SetPeriod, but only for all the channels in this PWM peripheral at once.
func (PWM) Channel
func (pwm PWM) Channel(pin Pin) (uint8, error)
Channel returns a PWM channel for the given pin.
func (PWM) Configure
func (pwm PWM) Configure(config PWMConfig) error
Configure enables and configures this PWM.
For the two 8 bit timers, there is only a limited number of periods available, namely the CPU frequency divided by 256 and again divided by 1, 8, 64, 256, or 1024. For a MCU running at 16MHz, this would be a period of 16µs, 128µs, 1024µs, 4096µs, or 16384µs.
func (PWM) Counter
func (pwm PWM) Counter() uint32
Counter returns the current counter value of the timer in this PWM peripheral. It may be useful for debugging.
func (PWM) Period
func (pwm PWM) Period() uint64
Period returns the used PWM period in nanoseconds. It might deviate slightly from the configured period due to rounding.
func (PWM) Set
func (pwm PWM) 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:
pwm.Set(channel, pwm.Top() / 4)
pwm.Set(channel, 0) will set the output to low and pwm.Set(channel, pwm.Top()) will set the output to high, assuming the output isn’t inverted.
func (PWM) SetInverting
func (pwm PWM) 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%.
Note: the invert state may not be applied on the AVR until the next call to ch.Set().
func (PWM) SetPeriod
func (pwm PWM) SetPeriod(period uint64) error
SetPeriod updates the period of this PWM 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 PWM 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 (PWM) Top
func (pwm PWM) 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 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 sets the pin to input or output.
func (Pin) Get
func (p Pin) Get() bool
Get returns the current value of a GPIO pin when the pin is 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() (*volatile.Register8, uint8)
Return the register and mask to disable a given port. This can be used to implement bit-banged drivers.
Warning: there are no separate pin set/clear registers on the AVR. The returned mask is only valid as long as no other pin in the same port has been changed.
func (Pin) PortMaskSet
func (p Pin) PortMaskSet() (*volatile.Register8, uint8)
Return the register and mask to enable a given GPIO pin. This can be used to implement bit-banged drivers.
Warning: there are no separate pin set/clear registers on the AVR. The returned mask is only valid as long as no other pin in the same port has been changed.
func (Pin) Set
func (p Pin) Set(value bool)
Set changes the value of the GPIO pin. The pin must be configured as output.
func (Pin) SetInterrupt
func (pin Pin) SetInterrupt(pinChange PinChange, callback func(Pin)) (err error)
type PinChange
type PinChange uint8
Pin Change Interrupts
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 {
// The registers for the SPIx port set by the chip
spcr *volatile.Register8
spdr *volatile.Register8
spsr *volatile.Register8
spcrR0 byte
spcrR1 byte
spcrCPHA byte
spcrCPOL byte
spcrDORD byte
spcrSPE byte
spcrMSTR byte
spsrI2X byte
spsrSPIF byte
// The io pins for the SPIx port set by the chip
sck Pin
sdi Pin
sdo Pin
cs Pin
}
SPI is for the Serial Peripheral Interface Data is taken from http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf page 169 and following
func (SPI) Configure
func (s SPI) Configure(config SPIConfig) error
Configure is intended to setup the SPI interface.
func (SPI) Transfer
func (s SPI) Transfer(b byte) (byte, error)
Transfer writes the byte into the register and returns the read content
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 {
Frequency uint32
LSBFirst bool
Mode uint8
}
SPIConfig is used to store config info for SPI.
type UART
type UART struct {
Buffer *RingBuffer
dataReg *volatile.Register8
baudRegH *volatile.Register8
baudRegL *volatile.Register8
statusRegA *volatile.Register8
statusRegB *volatile.Register8
statusRegC *volatile.Register8
}
UART on the AVR.
func (*UART) Buffered
func (uart *UART) Buffered() int
Buffered returns the number of bytes currently stored in the RX buffer.
func (*UART) Configure
func (uart *UART) Configure(config UARTConfig)
Configure the UART on the AVR. Defaults to 9600 baud on Arduino.
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) 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.