thingplus-rp2040

Constants

const (
	LED	= GPIO25

	// Onboard crystal oscillator frequency, in MHz.
	xoscFreq	= 12	// MHz
)
const (
	GP0	Pin	= GPIO0	// TX
	GP1	Pin	= GPIO1	// RX
	GP2	Pin	= GPIO2	// SCK
	GP3	Pin	= GPIO3	// COPI
	GP4	Pin	= GPIO4	// CIPO

	GP6	Pin	= GPIO6		// SDA
	GP7	Pin	= GPIO7		// SCL (connected to GPIO23 as well)
	GP8	Pin	= GPIO8		// WS2812 RGB LED
	GP9	Pin	= GPIO9		// muSDcard DATA3 / CS
	GP10	Pin	= GPIO10	// muSDcard DATA2
	GP11	Pin	= GPIO11	// muSDcard DATA1
	GP12	Pin	= GPIO12	// muSDcard DATA0 / CIPO

	GP14	Pin	= GPIO14	// muSDcard CLK /SCLK
	GP15	Pin	= GPIO15	// muSDcard CMD / COPI
	GP16	Pin	= GPIO16	// 16
	GP17	Pin	= GPIO17	// 17
	GP18	Pin	= GPIO18	// 18
	GP19	Pin	= GPIO19	// 19
	GP20	Pin	= GPIO20	// 20
	GP21	Pin	= GPIO21	// 21
	GP22	Pin	= GPIO22	// 22
	GP23	Pin	= GPIO23	// Connected to GPIO7
	GP25	Pin	= GPIO25	// Status blue LED
	GP26	Pin	= GPIO26	// ADC0
	GP27	Pin	= GPIO27	// ADC1
	GP28	Pin	= GPIO28	// ADC2
	GP29	Pin	= GPIO29	// ADC3
)

GPIO Pins

const (
	A0	= GPIO26
	A1	= GPIO27
	A2	= GPIO28
	A3	= GPIO29
)

Analog pins

const (
	I2C0_SCL_PIN	= GPIO6	// N/A
	I2C0_SDA_PIN	= GPIO7	// N/A

	I2C1_SDA_PIN	= GPIO6
	I2C1_SCL_PIN	= GPIO7

	SDA_PIN	= I2C1_SDA_PIN
	SCL_PIN	= I2C1_SCL_PIN
)

I2C Pins.

const (
	// Default Serial Clock Bus 0 for SPI communications
	SPI0_SCK_PIN	= GPIO2
	// Default Serial Out Bus 0 for SPI communications
	SPI0_SDO_PIN	= GPIO3	// Tx
	// Default Serial In Bus 0 for SPI communications
	SPI0_SDI_PIN	= GPIO4	// Rx

	// Default Serial Clock Bus 1 for SPI communications to muSDcard
	SPI1_SCK_PIN	= GPIO14
	// Default Serial Out Bus 1 for SPI communications to muSDcard
	SPI1_SDO_PIN	= GPIO15	// Tx
	// Default Serial In Bus 1 for SPI communications to muSDcard
	SPI1_SDI_PIN	= GPIO12	// Rx
)

SPI default 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 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 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 (
	// GPIO pins
	GPIO0	Pin	= 0
	GPIO1	Pin	= 1
	GPIO2	Pin	= 2
	GPIO3	Pin	= 3
	GPIO4	Pin	= 4
	GPIO5	Pin	= 5
	GPIO6	Pin	= 6
	GPIO7	Pin	= 7
	GPIO8	Pin	= 8
	GPIO9	Pin	= 9
	GPIO10	Pin	= 10
	GPIO11	Pin	= 11
	GPIO12	Pin	= 12
	GPIO13	Pin	= 13
	GPIO14	Pin	= 14
	GPIO15	Pin	= 15
	GPIO16	Pin	= 16
	GPIO17	Pin	= 17
	GPIO18	Pin	= 18
	GPIO19	Pin	= 19
	GPIO20	Pin	= 20
	GPIO21	Pin	= 21
	GPIO22	Pin	= 22
	GPIO23	Pin	= 23
	GPIO24	Pin	= 24
	GPIO25	Pin	= 25
	GPIO26	Pin	= 26
	GPIO27	Pin	= 27
	GPIO28	Pin	= 28
	GPIO29	Pin	= 29

	// Analog pins
	ADC0	Pin	= GPIO26
	ADC1	Pin	= GPIO27
	ADC2	Pin	= GPIO28
	ADC3	Pin	= GPIO29
)
const (
	UART_TX_PIN	= UART0_TX_PIN
	UART_RX_PIN	= UART0_RX_PIN
	UART0_TX_PIN	= GPIO0
	UART0_RX_PIN	= GPIO1
	UART1_TX_PIN	= GPIO8
	UART1_RX_PIN	= GPIO9
)

UART pins

const (
	adc0_CH	ADCChannel	= iota
	adc1_CH
	adc2_CH
	adc3_CH		// Note: GPIO29 not broken out on pico board
	ADC_TEMP_SENSOR	// Internal temperature sensor channel
)

ADC channels. Only ADC_TEMP_SENSOR is public. The other channels are accessed via Machine.ADC objects

const (
	KHz	= 1000
	MHz	= 1000000
)
const (
	PinOutput	PinMode	= iota
	PinInput
	PinInputPulldown
	PinInputPullup
	PinAnalog
	PinUART
	PinPWM
	PinI2C
	PinSPI
)
const (
	// PinLevelLow triggers whenever pin is at a low (around 0V) logic level.
	PinLevelLow	PinChange	= 1 << iota
	// PinLevelLow triggers whenever pin is at a high (around 3V) logic level.
	PinLevelHigh
	// Edge falling
	PinFalling
	// Edge rising
	PinRising
)

Pin change interrupt constants for SetInterrupt.

const RESETS_RESET_Msk = 0x01ffffff

RESETS_RESET_Msk is bitmask to reset all peripherals

TODO: This field is not available in the device file.

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 (
	ErrTimeoutRNG		= errors.New("machine: RNG Timeout")
	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{
		Buffer:	NewRingBuffer(),
		Bus:	rp.UART0,
	}

	UART1	= &_UART1
	_UART1	= UART{
		Buffer:	NewRingBuffer(),
		Bus:	rp.UART1,
	}
)

UART on the RP2040

var DefaultUART = UART0
var (
	I2C0	= &_I2C0
	_I2C0	= I2C{
		Bus: rp.I2C0,
	}
	I2C1	= &_I2C1
	_I2C1	= I2C{
		Bus: rp.I2C1,
	}
)

I2C on the RP2040.

var (
	ErrInvalidI2CBaudrate	= errors.New("invalid i2c baudrate")
	ErrInvalidTgtAddr	= errors.New("invalid target i2c address not in 0..0x80 or is reserved")
	ErrI2CGeneric		= errors.New("i2c error")
	ErrRP2040I2CDisable	= errors.New("i2c rp2040 peripheral timeout in disable")
)
var (
	ErrBadPeriod = errors.New("period outside valid range 8ns..268ms")
)
var (
	PWM0	= getPWMGroup(0)
	PWM1	= getPWMGroup(1)
	PWM2	= getPWMGroup(2)
	PWM3	= getPWMGroup(3)
	PWM4	= getPWMGroup(4)
	PWM5	= getPWMGroup(5)
	PWM6	= getPWMGroup(6)
	PWM7	= getPWMGroup(7)
)

Hardware Pulse Width Modulation (PWM) API PWM peripherals available on RP2040. Each peripheral has 2 pins available for a total of 16 available PWM outputs. Some pins may not be available on some boards.

The RP2040 PWM block has 8 identical slices. Each slice can drive two PWM output signals, or measure the frequency or duty cycle of an input signal. This gives a total of up to 16 controllable PWM outputs. All 30 GPIOs can be driven by the PWM block

The PWM hardware functions by continuously comparing the input value to a free-running counter. This produces a toggling output where the amount of time spent at the high output level is proportional to the input value. The fraction of time spent at the high signal level is known as the duty cycle of the signal.

The default behaviour of a PWM slice is to count upward until the wrap value (\ref pwm_config_set_wrap) is reached, and then immediately wrap to 0. PWM slices also offer a phase-correct mode, where the counter starts to count downward after reaching TOP, until it reaches 0 again.

var (
	SPI0	= &_SPI0
	_SPI0	= SPI{
		Bus: rp.SPI0,
	}
	SPI1	= &_SPI1
	_SPI1	= SPI{
		Bus: rp.SPI1,
	}
)

SPI on the RP2040

var (
	ErrLSBNotSupported	= errors.New("SPI LSB unsupported on PL022")
	ErrTxInvalidSliceSize	= errors.New("SPI write and read slices must be same size")
	ErrSPITimeout		= errors.New("SPI timeout")
	ErrSPIBaud		= errors.New("SPI baud too low or above 66.5Mhz")
)
var (
	ErrPWMPeriodTooLong = errors.New("pwm: period too long")
)
var Serial = DefaultUART

Serial is implemented via the default (usually the first) UART on the chip.

func CPUFrequency

func CPUFrequency() uint32

func CurrentCore

func CurrentCore() int

CurrentCore returns the core number the call was made from.

func InitADC

func InitADC()

InitADC resets the ADC peripheral.

func NewRingBuffer

func NewRingBuffer() *RingBuffer

NewRingBuffer returns a new ring buffer.

func NumCores

func NumCores() int

NumCores returns number of cores available on the device.

func PWMPeripheral

func PWMPeripheral(pin Pin) (sliceNum uint8, err error)

Peripheral returns the RP2040 PWM peripheral which ranges from 0 to 7. Each PWM peripheral has 2 channels, A and B which correspond to 0 and 1 in the program. This number corresponds to the package’s PWM0 throughout PWM7 handles

type ADC

type ADC struct {
	Pin Pin
}

func (ADC) Configure

func (a ADC) Configure(config ADCConfig) error

Configure sets the ADC pin to analog input mode.

func (ADC) Get

func (a ADC) Get() uint16

Get returns a one-shot ADC sample reading.

func (ADC) GetADCChannel

func (a ADC) GetADCChannel() (c ADCChannel, err error)

GetADCChannel returns the channel associated with the ADC pin.

type ADCChannel

type ADCChannel uint8

ADCChannel is the ADC peripheral mux channel. 0-4.

func (ADCChannel) Configure

func (c ADCChannel) Configure(config ADCConfig) error

Configure sets the channel’s associated pin to analog input mode or powers on the temperature sensor for ADC_TEMP_SENSOR. The powered on temperature sensor increases ADC_AVDD current by approximately 40 μA.

func (ADCChannel) Pin

func (c ADCChannel) Pin() (p Pin, err error)

The Pin method returns the GPIO Pin associated with the ADC mux channel, if it has one.

func (ADCChannel) ReadTemperature

func (c ADCChannel) ReadTemperature() (millicelsius uint32)

ReadTemperature does a one-shot sample of the internal temperature sensor and returns a milli-celsius reading. Only works on the ADC_TEMP_SENSOR channel. aka AINSEL=4. Other channels will return 0

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		*rp.I2C0_Type
	restartOnNext	bool
}

func (*I2C) Configure

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

Configure initializes i2c peripheral and configures I2C config’s pins passed. Here’s a list of valid SDA and SCL GPIO pins on bus I2C0 of the rp2040: SDA: 0, 4, 8, 12, 16, 20 SCL: 1, 5, 9, 13, 17, 21 Same as above for I2C1 bus: SDA: 2, 6, 10, 14, 18, 26 SCL: 3, 7, 11, 15, 19, 27

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 I2C frequency. It has the side effect of also enabling the I2C hardware if disabled beforehand.

func (*I2C) Tx

func (i2c *I2C) Tx(addr uint16, w, r []byte) error

Tx performs a write and then a read transfer placing the result in in r.

Passing a nil value for w or r skips the transfer corresponding to write or read, respectively.

i2c.Tx(addr, nil, r) Performs only a read transfer.

i2c.Tx(addr, w, nil) Performs only a write transfer.

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
	// SDA/SCL Serial Data and clock pins. Refer to datasheet to see
	// which pins match the desired bus.
	SDA, SCL	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 configures the gpio pin as per mode.

func (Pin) Get

func (p Pin) Get() bool

Get reads the pin value.

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.Register32, uint32)

func (Pin) PortMaskSet

func (p Pin) PortMaskSet() (*volatile.Register32, uint32)

func (Pin) Set

func (p Pin) Set(value bool)

Set drives the pin high if value is true else drives it low.

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

PinChange represents one or more trigger events that can happen on a given GPIO pin on the RP2040. ORed PinChanges are valid input to most IRQ functions.

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 *rp.SPI0_Type
}

func (SPI) Configure

func (spi SPI) Configure(config SPIConfig) error

Configure is intended to setup/initialize the SPI interface. Default baudrate of 115200 is used if Frequency == 0. Default word length (data bits) is 8. Below is a list of GPIO pins corresponding to SPI0 bus on the rp2040: SI : 0, 4, 17 a.k.a RX and MISO (if rp2040 is master) SO : 3, 7, 19 a.k.a TX and MOSI (if rp2040 is master) SCK: 2, 6, 18 SPI1 bus GPIO pins: SI : 8, 12 SO : 11, 15 SCK: 10, 14 No pin configuration is needed of SCK, SDO and SDI needed after calling Configure.

func (SPI) GetBaudRate

func (spi SPI) GetBaudRate() uint32

func (SPI) PrintRegs

func (spi SPI) PrintRegs()

PrintRegs prints SPI’s peripheral common registries current values

func (SPI) SetBaudRate

func (spi SPI) SetBaudRate(br uint32) error

func (SPI) Transfer

func (spi SPI) Transfer(w byte) (byte, error)

Write a single byte and read a single byte from TX/RX FIFO.

func (SPI) Tx

func (spi SPI) Tx(w, r []byte) (err 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)

Remark: This implementation (RP2040) allows reading into buffer with a custom repeated value on tx.

    spi.Tx([]byte{0xff}, rx) // may cause unwanted heap allocations.

This form sends 0xff and puts the result into rx buffer. Useful for reading from SD cards which require 0xff input on SI.

type SPIConfig

type SPIConfig struct {
	Frequency	uint32
	// LSB not supported on rp2040.
	LSBFirst	bool
	// Mode's two most LSB are CPOL and CPHA. i.e. Mode==2 (0b10) is CPOL=1, CPHA=0
	Mode	uint8
	// Number of data bits per transfer. Valid values 4..16. Default and recommended is 8.
	DataBits	uint8
	// Serial clock pin
	SCK	Pin
	// TX or Serial Data Out (MOSI if rp2040 is master)
	SDO	Pin
	// RX or Serial Data In (MISO if rp2040 is master)
	SDI	Pin
}

SPIConfig is used to store config info for SPI.

type UART

type UART struct {
	Buffer		*RingBuffer
	Bus		*rp.UART0_Type
	Interrupt	interrupt.Interrupt
}

UART on the RP2040.

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 baudrate to be used for the UART.

func (*UART) SetFormat

func (uart *UART) SetFormat(databits, stopbits uint8, parity UARTParity) error

SetFormat for number of data bits, stop bits, and parity for the UART.

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.