hifive1b

Constants

const (
	P00	Pin	= 0
	P01	Pin	= 1
	P02	Pin	= 2
	P03	Pin	= 3
	P04	Pin	= 4
	P05	Pin	= 5
	P06	Pin	= 6
	P07	Pin	= 7
	P08	Pin	= 8
	P09	Pin	= 9
	P10	Pin	= 10
	P11	Pin	= 11
	P12	Pin	= 12
	P13	Pin	= 13
	P14	Pin	= 14
	P15	Pin	= 15
	P16	Pin	= 16
	P17	Pin	= 17
	P18	Pin	= 18
	P19	Pin	= 19
	P20	Pin	= 20
	P21	Pin	= 21
	P22	Pin	= 22
	P23	Pin	= 23
	P24	Pin	= 24
	P25	Pin	= 25
	P26	Pin	= 26
	P27	Pin	= 27
	P28	Pin	= 28
	P29	Pin	= 29
	P30	Pin	= 30
	P31	Pin	= 31
)
const (
	D0	= P16
	D1	= P17
	D2	= P18
	D3	= P19	// Green LED/PWM (PWM1_PWM1)
	D4	= P20	// PWM (PWM1_PWM0)
	D5	= P21	// Blue LED/PWM (PWM1_PWM2)
	D6	= P22	// Red LED/PWM (PWM1_PWM3)
	D7	= P16
	D8	= NoPin	// PWM?
	D9	= P01
	D10	= P02	// SPI1_CS0
	D11	= P03	// SPI1_DQ0
	D12	= P04	// SPI1_DQ1
	D13	= P05	// SPI1_SCK
	D14	= NoPin	// not connected
	D15	= P09	// does not seem to work?
	D16	= P10	// PWM (PWM2_PWM0)
	D17	= P11	// PWM (PWM2_PWM1)
	D18	= P12	// SDA (I2C0_SDA)/PWM (PWM2_PWM2)
	D19	= P13	// SDL (I2C0_SCL)/PWM (PWM2_PWM3)
)
const (
	LED		= LED1
	LED1		= LED_RED
	LED2		= LED_GREEN
	LED3		= LED_BLUE
	LED_RED		= P22
	LED_GREEN	= P19
	LED_BLUE	= P21
)
const (
	// TODO: figure out the pin numbers for these.
	UART_TX_PIN	= D1
	UART_RX_PIN	= D0
)
const (
	SPI0_SCK_PIN	= NoPin
	SPI0_SDO_PIN	= NoPin
	SPI0_SDI_PIN	= NoPin

	SPI1_SCK_PIN	= D13
	SPI1_SDO_PIN	= D11
	SPI1_SDI_PIN	= D12
)

SPI pins

const (
	I2C0_SDA_PIN	= D18
	I2C0_SCL_PIN	= D19
)

I2C pins

const (
	TWI_FREQ_100KHZ	= 100000
	TWI_FREQ_400KHZ	= 400000
)

TWI_FREQ is the I2C bus speed. Normally either 100 kHz, or 400 kHz for high-speed bus.

const 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 (
	PinInput	PinMode	= iota
	PinOutput
	PinPWM
	PinSPI
	PinI2C	= PinSPI
)
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	= 0

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

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

Variables

var DefaultUART = UART0
var (
	SPI1 = SPI{
		Bus: sifive.QSPI1,
	}
)

SPI on the HiFive1.

var (
	ErrInvalidInputPin	= errors.New("machine: invalid input pin")
	ErrInvalidOutputPin	= errors.New("machine: invalid output pin")
	ErrInvalidClockPin	= errors.New("machine: invalid clock pin")
	ErrInvalidDataPin	= errors.New("machine: invalid data pin")
	ErrNoPinChangeChannel	= errors.New("machine: no channel available for pin interrupt")
)
var (
	UART0	= &_UART0
	_UART0	= UART{Bus: sifive.UART0, Buffer: NewRingBuffer()}
)
var (
	I2C0 = (*I2C)(unsafe.Pointer(sifive.I2C0))
)
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

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

type ADC

type ADC struct {
	Pin Pin
}

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 I2C

type I2C struct {
	Bus sifive.I2C_Type
}

I2C on the FE310-G002.

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) 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
	SCL		Pin
	SDA		Pin
}

I2CConfig is used to store config info for I2C.

type NullSerial

type NullSerial struct {
}

NullSerial is a serial version of /dev/null (or null router): it drops everything that is written to it.

func (NullSerial) Buffered

func (ns NullSerial) Buffered() int

Buffered returns how many bytes are buffered in the UART. It always returns 0 as there are no bytes to read.

func (NullSerial) Configure

func (ns NullSerial) Configure(config UARTConfig) error

Configure does nothing: the null serial has no configuration.

func (NullSerial) ReadByte

func (ns NullSerial) ReadByte() (byte, error)

ReadByte always returns an error because there aren’t any bytes to read.

func (NullSerial) Write

func (ns NullSerial) Write(p []byte) (n int, err error)

Write is a no-op: none of the data is being written and it will not return an error.

func (NullSerial) WriteByte

func (ns NullSerial) WriteByte(b byte) error

WriteByte is a no-op: the null serial doesn’t write bytes.

type PWMConfig

type PWMConfig struct {
	// PWM period in nanosecond. Leaving this zero will pick a reasonable period
	// value for use with LEDs.
	// If you want to configure a frequency instead of a period, you can use the
	// following formula to calculate a period from a frequency:
	//
	//     period = 1e9 / frequency
	//
	Period uint64
}

PWMConfig allows setting some configuration while configuring a PWM peripheral. A zero PWMConfig is ready to use for simple applications such as dimming LEDs.

type Pin

type Pin uint8

Pin is a single pin on a chip, which may be connected to other hardware devices. It can either be used directly as GPIO pin or it can be used in other peripherals like ADC, I2C, etc.

func (Pin) Configure

func (p Pin) Configure(config PinConfig)

Configure this pin with the given configuration.

func (Pin) Get

func (p Pin) Get() bool

Get returns the current value of a GPIO pin.

func (Pin) High

func (p Pin) High()

High sets this GPIO pin to high, assuming it has been configured as an output pin. It is hardware dependent (and often undefined) what happens if you set a pin to high that is not configured as an output pin.

func (Pin) Low

func (p Pin) Low()

Low sets this GPIO pin to low, assuming it has been configured as an output pin. It is hardware dependent (and often undefined) what happens if you set a pin to low that is not configured as an output pin.

func (Pin) Set

func (p Pin) Set(high bool)

Set the pin to high or low.

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 *sifive.QSPI_Type
}

SPI on the FE310. The normal SPI0 is actually a quad-SPI meant for flash, so it is best to use SPI1 or SPI2 port for most applications.

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 UART

type UART struct {
	Bus	*sifive.UART_Type
	Buffer	*RingBuffer
}

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)

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 to the UART.

func (*UART) WriteByte

func (uart *UART) WriteByte(c byte)

type UARTConfig

type UARTConfig struct {
	BaudRate	uint32
	TX		Pin
	RX		Pin
}

UARTConfig is a struct with which a UART (or similar object) can be configured. The baud rate is usually respected, but TX and RX may be ignored depending on the chip and the type of object.

type UARTParity

type UARTParity int

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