bluepill

Constants

const (
	LED = PC13
)
const (
	// This board does not have a user button, so
	// use first GPIO pin by default
	BUTTON = PA0
)
const (
	UART_TX_PIN	= PA9
	UART_RX_PIN	= PA10
	UART_ALT_TX_PIN	= PB6
	UART_ALT_RX_PIN	= PB7
)

UART pins

const (
	SPI0_SCK_PIN	= PA5
	SPI0_SDO_PIN	= PA7
	SPI0_SDI_PIN	= PA6
)

SPI pins

const (
	I2C0_SDA_PIN	= PB7
	I2C0_SCL_PIN	= PB6
)

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 (
	PinRising	PinChange	= 1 << iota
	PinFalling
	PinToggle	= PinRising | PinFalling
)
const (
	DutyCycle2	= 0
	DutyCycle16x9	= 1
)

I2C fast mode (Fm) duty cycle

const PWM_MODE1 = 0x6
const APB1_TIM_FREQ = 72e6	// 72MHz

Internal use: configured speed of the APB1 and APB2 timers, this should be kept in sync with any changes to runtime package which configures the oscillators and clock frequencies

const APB2_TIM_FREQ = 72e6	// 72MHz

const (
	PinInput	PinMode	= 0	// Input mode
	PinOutput10MHz	PinMode	= 1	// Output mode, max speed 10MHz
	PinOutput2MHz	PinMode	= 2	// Output mode, max speed 2MHz
	PinOutput50MHz	PinMode	= 3	// Output mode, max speed 50MHz
	PinOutput	PinMode	= PinOutput2MHz

	PinInputModeAnalog	PinMode	= 0	// Input analog mode
	PinInputModeFloating	PinMode	= 4	// Input floating mode
	PinInputModePullUpDown	PinMode	= 8	// Input pull up/down mode
	PinInputModeReserved	PinMode	= 12	// Input mode (reserved)

	PinOutputModeGPPushPull		PinMode	= 0	// Output mode general purpose push/pull
	PinOutputModeGPOpenDrain	PinMode	= 4	// Output mode general purpose open drain
	PinOutputModeAltPushPull	PinMode	= 8	// Output mode alt. purpose push/pull
	PinOutputModeAltOpenDrain	PinMode	= 12	// Output mode alt. purpose open drain

	// Pull-up vs Pull down is not part of the CNF0 / CNF1 bits, but is
	// controlled by PxODR.  Encoded using the 'spare' bit 5.
	PinInputPulldown	PinMode	= PinInputModePullUpDown
	PinInputPullup		PinMode	= PinInputModePullUpDown | 0x10
)
const (
	PA0	= portA + 0
	PA1	= portA + 1
	PA2	= portA + 2
	PA3	= portA + 3
	PA4	= portA + 4
	PA5	= portA + 5
	PA6	= portA + 6
	PA7	= portA + 7
	PA8	= portA + 8
	PA9	= portA + 9
	PA10	= portA + 10
	PA11	= portA + 11
	PA12	= portA + 12
	PA13	= portA + 13
	PA14	= portA + 14
	PA15	= portA + 15

	PB0	= portB + 0
	PB1	= portB + 1
	PB2	= portB + 2
	PB3	= portB + 3
	PB4	= portB + 4
	PB5	= portB + 5
	PB6	= portB + 6
	PB7	= portB + 7
	PB8	= portB + 8
	PB9	= portB + 9
	PB10	= portB + 10
	PB11	= portB + 11
	PB12	= portB + 12
	PB13	= portB + 13
	PB14	= portB + 14
	PB15	= portB + 15

	PC0	= portC + 0
	PC1	= portC + 1
	PC2	= portC + 2
	PC3	= portC + 3
	PC4	= portC + 4
	PC5	= portC + 5
	PC6	= portC + 6
	PC7	= portC + 7
	PC8	= portC + 8
	PC9	= portC + 9
	PC10	= portC + 10
	PC11	= portC + 11
	PC12	= portC + 12
	PC13	= portC + 13
	PC14	= portC + 14
	PC15	= portC + 15

	PD0	= portD + 0
	PD1	= portD + 1
	PD2	= portD + 2
	PD3	= portD + 3
	PD4	= portD + 4
	PD5	= portD + 5
	PD6	= portD + 6
	PD7	= portD + 7
	PD8	= portD + 8
	PD9	= portD + 9
	PD10	= portD + 10
	PD11	= portD + 11
	PD12	= portD + 12
	PD13	= portD + 13
	PD14	= portD + 14
	PD15	= portD + 15

	PE0	= portE + 0
	PE1	= portE + 1
	PE2	= portE + 2
	PE3	= portE + 3
	PE4	= portE + 4
	PE5	= portE + 5
	PE6	= portE + 6
	PE7	= portE + 7
	PE8	= portE + 8
	PE9	= portE + 9
	PE10	= portE + 10
	PE11	= portE + 11
	PE12	= portE + 12
	PE13	= portE + 13
	PE14	= portE + 14
	PE15	= portE + 15

	PF0	= portF + 0
	PF1	= portF + 1
	PF2	= portF + 2
	PF3	= portF + 3
	PF4	= portF + 4
	PF5	= portF + 5
	PF6	= portF + 6
	PF7	= portF + 7
	PF8	= portF + 8
	PF9	= portF + 9
	PF10	= portF + 10
	PF11	= portF + 11
	PF12	= portF + 12
	PF13	= portF + 13
	PF14	= portF + 14
	PF15	= portF + 15
)

Pin constants for all stm32f103 package sizes

const (
	ARR_MAX	= 0x10000
	PSC_MAX	= 0x10000
)
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 = UART1
var (
	// USART1 is the first hardware serial port on the STM32.
	UART1	= &_UART1
	_UART1	= UART{
		Buffer:	NewRingBuffer(),
		Bus:	stm32.USART1,
	}
	UART2	= &_UART2
	_UART2	= UART{
		Buffer:	NewRingBuffer(),
		Bus:	stm32.USART2,
	}
)
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 (
	SPI1	= SPI{Bus: stm32.SPI1}
	SPI0	= SPI1
)

There are 3 SPI interfaces on the STM32F103xx. Since the first interface is named SPI1, both SPI0 and SPI1 refer to SPI1. TODO: implement SPI2 and SPI3.

var (
	I2C1	= &I2C{Bus: stm32.I2C1}
	I2C0	= I2C1
)
var (
	TIM1	= TIM{
		EnableRegister:	&stm32.RCC.APB2ENR,
		EnableFlag:	stm32.RCC_APB2ENR_TIM1EN,
		Device:		stm32.TIM1,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PE9, 0b11}, {PA8, 0b00}}},
			TimerChannel{Pins: []PinFunction{{PE11, 0b11}, {PA9, 0b00}}},
			TimerChannel{Pins: []PinFunction{{PE13, 0b11}, {PA10, 0b00}}},
			TimerChannel{Pins: []PinFunction{{PE14, 0b11}, {PA11, 0b00}}},
		},
		busFreq:	APB2_TIM_FREQ,
	}

	TIM2	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM2EN,
		Device:		stm32.TIM2,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PA0, 0b00}, {PA15, 0b01}}},
			TimerChannel{Pins: []PinFunction{{PA1, 0b00}, {PB3, 0b01}}},
			TimerChannel{Pins: []PinFunction{{PA2, 0b00}, {PB10, 0b10}}},
			TimerChannel{Pins: []PinFunction{{PA3, 0b00}, {PB11, 0b10}}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM3	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM3EN,
		Device:		stm32.TIM3,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PA6, 0b00}, {PC6, 0b11}, {PB4, 0b10}}},
			TimerChannel{Pins: []PinFunction{{PA7, 0b00}, {PC7, 0b11}, {PB5, 0b10}}},
			TimerChannel{Pins: []PinFunction{{PB0, 0b00}, {PC8, 0b11}}},
			TimerChannel{Pins: []PinFunction{{PB1, 0b00}, {PC9, 0b11}}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM4	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM4EN,
		Device:		stm32.TIM4,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PD12, 0b1}, {PB6, 0}}},
			TimerChannel{Pins: []PinFunction{{PD13, 0b1}, {PB7, 0}}},
			TimerChannel{Pins: []PinFunction{{PD14, 0b1}, {PB8, 0}}},
			TimerChannel{Pins: []PinFunction{{PD15, 0b1}, {PB9, 0}}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM5	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM5EN,
		Device:		stm32.TIM5,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{{PA3, 0b0}}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM6	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM6EN,
		Device:		stm32.TIM6,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM7	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM7EN,
		Device:		stm32.TIM7,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM8	= TIM{
		EnableRegister:	&stm32.RCC.APB2ENR,
		EnableFlag:	stm32.RCC_APB2ENR_TIM8EN,
		Device:		stm32.TIM8,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB2_TIM_FREQ,
	}

	TIM9	= TIM{
		EnableRegister:	&stm32.RCC.APB2ENR,
		EnableFlag:	stm32.RCC_APB2ENR_TIM9EN,
		Device:		stm32.TIM9,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PA2, 0b0}, {PE5, 0b1}}},
			TimerChannel{Pins: []PinFunction{{PA3, 0b0}, {PE6, 0b1}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB2_TIM_FREQ,
	}

	TIM10	= TIM{
		EnableRegister:	&stm32.RCC.APB2ENR,
		EnableFlag:	stm32.RCC_APB2ENR_TIM10EN,
		Device:		stm32.TIM10,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PB8, 0b0}, {PF6, 0b1}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB2_TIM_FREQ,
	}

	TIM11	= TIM{
		EnableRegister:	&stm32.RCC.APB2ENR,
		EnableFlag:	stm32.RCC_APB2ENR_TIM11EN,
		Device:		stm32.TIM11,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PB9, 0b0}, {PF7, 0b1}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB2_TIM_FREQ,
	}

	TIM12	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM12EN,
		Device:		stm32.TIM12,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM13	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM13EN,
		Device:		stm32.TIM13,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PA6, 0b0}, {PF8, 0b1}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB1_TIM_FREQ,
	}

	TIM14	= TIM{
		EnableRegister:	&stm32.RCC.APB1ENR,
		EnableFlag:	stm32.RCC_APB1ENR_TIM14EN,
		Device:		stm32.TIM14,
		Channels: [4]TimerChannel{
			TimerChannel{Pins: []PinFunction{{PA7, 0b0}, {PF9, 0b1}}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
			TimerChannel{Pins: []PinFunction{}},
		},
		busFreq:	APB1_TIM_FREQ,
	}
)
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 ChannelCallback

type ChannelCallback func(channel uint8)

type I2C

type I2C struct {
	Bus *stm32.I2C_Type
}

func (*I2C) Configure

func (i2c *I2C) Configure(config I2CConfig) error

Configure is intended to setup the STM32 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

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
	DutyCycle	uint8
}

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 I/O settings. stm32f1xx uses different technique for setting the GPIO pins than the stm32f407

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. 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

———- General pin operations ———-

type PinConfig

type PinConfig struct {
	Mode PinMode
}

type PinFunction

type PinFunction struct {
	Pin	Pin
	AltFunc	uint8
}

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 *stm32.SPI_Type
}

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig)

Configure is intended to setup the STM32 SPI1 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 TIM

type TIM struct {
	EnableRegister	*volatile.Register32
	EnableFlag	uint32
	Device		*stm32.TIM_Type
	Channels	[4]TimerChannel
	UpInterrupt	interrupt.Interrupt
	OCInterrupt	interrupt.Interrupt

	wraparoundCallback	TimerCallback
	channelCallbacks	[4]ChannelCallback

	busFreq	uint64
}

func (*TIM) Channel

func (t *TIM) Channel(pin Pin) (uint8, error)

Channel returns a PWM channel for the given pin.

func (*TIM) Configure

func (t *TIM) Configure(config PWMConfig) error

Configure enables and configures this PWM.

func (*TIM) Count

func (t *TIM) Count() uint32

func (*TIM) Set

func (t *TIM) Set(channel uint8, value uint32)

Set updates the channel value. This is used to control the channel duty cycle. For example, to set it to a 25% duty cycle, use:

t.Set(ch, t.Top() / 4)

ch.Set(0) will set the output to low and ch.Set(ch.Top()) will set the output to high, assuming the output isn’t inverted.

func (*TIM) SetInverting

func (t *TIM) 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 (*TIM) SetMatchInterrupt

func (t *TIM) SetMatchInterrupt(channel uint8, callback ChannelCallback) error

Sets a callback to be called when a channel reaches it’s set-point.

For example, if t.Set(ch, t.Top() / 4) is used then the callback will be called every quarter-period of the timer’s base Period.

func (*TIM) SetPeriod

func (t *TIM) 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 (*TIM) SetWraparoundInterrupt

func (t *TIM) SetWraparoundInterrupt(callback TimerCallback) error

SetWraparoundInterrupt configures a callback to be called each time the timer ‘wraps-around’.

For example, if Configure(PWMConfig{Period:1000000}) is used, to set the timer period to 1ms, this callback will be called every 1ms.

func (*TIM) Top

func (t *TIM) 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 pwm.Set (see pwm.Set for more information).

func (*TIM) Unset

func (t *TIM) Unset(channel uint8)

Unset disables a channel, including any configured interrupts.

type TimerCallback

type TimerCallback func()

type TimerChannel

type TimerChannel struct {
	Pins []PinFunction
}

type UART

type UART struct {
	Buffer			*RingBuffer
	Bus			*stm32.USART_Type
	Interrupt		interrupt.Interrupt
	TxAltFuncSelector	uint8
	RxAltFuncSelector	uint8

	// Registers specific to the chip
	rxReg		*volatile.Register32
	txReg		*volatile.Register32
	statusReg	*volatile.Register32
	txEmptyFlag	uint32
}

UART representation

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.

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. Defer to chip-specific routines for calculation

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 int

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