esp32-coreboard-v2
Constants
const (
CLK = GPIO6
CMD = GPIO11
IO0 = GPIO0
IO1 = GPIO1
IO2 = GPIO2
IO3 = GPIO3
IO4 = GPIO4
IO5 = GPIO5
IO9 = GPIO9
IO10 = GPIO10
IO16 = GPIO16
IO17 = GPIO17
IO18 = GPIO18
IO19 = GPIO19
IO21 = GPIO21
IO22 = GPIO22
IO23 = GPIO23
IO25 = GPIO25
IO26 = GPIO26
IO27 = GPIO27
IO32 = GPIO32
IO33 = GPIO33
IO34 = GPIO34
IO35 = GPIO35
IO36 = GPIO36
IO39 = GPIO39
RXD = GPIO3
SD0 = GPIO7
SD1 = GPIO8
SD2 = GPIO9
SD3 = GPIO10
SVN = GPIO39
SVP = GPIO36
TCK = GPIO13
TD0 = GPIO15
TDI = GPIO12
TMS = GPIO14
TXD = GPIO1
)
const LED = IO2
Built-in LED on some ESP32 boards.
const (
SPI0_SCK_PIN = IO18
SPI0_SDO_PIN = IO23
SPI0_SDI_PIN = IO19
SPI0_CS0_PIN = IO5
)
SPI pins
const (
SDA_PIN = IO21
SCL_PIN = IO22
)
I2C pins
const (
ADC0 Pin = IO34
ADC1 Pin = IO35
ADC2 Pin = IO36
ADC3 Pin = IO39
)
ADC pins
const (
UART_TX_PIN = IO1
UART_RX_PIN = IO3
)
UART0 pins
const (
UART1_TX_PIN = IO9
UART1_RX_PIN = IO10
)
UART1 pins
const (
PWM0_PIN Pin = IO2
PWM1_PIN Pin = IO0
PWM2_PIN Pin = IO4
)
PWM 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.
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 (
PinOutput PinMode = iota
PinInput
PinInputPullup
PinInputPulldown
)
const (
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
GPIO21 Pin = 21
GPIO22 Pin = 22
GPIO23 Pin = 23
GPIO25 Pin = 25
GPIO26 Pin = 26
GPIO27 Pin = 27
GPIO32 Pin = 32
GPIO33 Pin = 33
GPIO34 Pin = 34
GPIO35 Pin = 35
GPIO36 Pin = 36
GPIO37 Pin = 37
GPIO38 Pin = 38
GPIO39 Pin = 39
)
Hardware pin numbers
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 (
ErrInvalidSPIBus = errors.New("machine: invalid SPI bus")
)
var DefaultUART = UART0
var (
UART0 = &_UART0
_UART0 = UART{Bus: esp.UART0, Buffer: NewRingBuffer()}
UART1 = &_UART1
_UART1 = UART{Bus: esp.UART1, Buffer: NewRingBuffer()}
UART2 = &_UART2
_UART2 = UART{Bus: esp.UART2, Buffer: NewRingBuffer()}
)
var (
// SPI0 and SPI1 are reserved for use by the caching system etc.
SPI2 = SPI{esp.SPI2}
SPI3 = SPI{esp.SPI3}
)
var (
I2C0 = &I2C{Bus: esp.I2C0, funcSCL: 29, funcSDA: 30}
I2C1 = &I2C{Bus: esp.I2C1, funcSCL: 95, funcSDA: 96}
)
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
CPUFrequency returns the current CPU frequency of the chip. Currently it is a fixed frequency but it may allow changing in the future.
func InitSerial
func InitSerial()
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)
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 {
Bus *esp.I2C_Type
funcSCL, funcSDA uint32
config I2CConfig
}
func (*I2C) CheckDevice
func (i2c *I2C) CheckDevice(addr uint16) bool
CheckDevice does an empty I2C transaction at the specified address. This can be used to find out if any device with that address is connected, e.g. for enumerating all devices on the bus.
func (*I2C) Configure
func (i2c *I2C) Configure(config I2CConfig) error
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
func (*I2C) Tx
func (i2c *I2C) Tx(addr uint16, w, r []byte) (err 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 // in Hz
SCL Pin
SDA Pin
}
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 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 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() (*uint32, uint32)
Return the register and mask to disable a given GPIO pin. This can be used to implement bit-banged drivers.
Warning: only use this on an output pin!
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.
Warning: only use this on an output pin!
func (Pin) Set
func (p Pin) Set(value bool)
Set the pin to high or low. Warning: only use this on an output pin!
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 *esp.SPI_Type
}
Serial Peripheral Interface on the ESP32.
func (SPI) Configure
func (spi SPI) Configure(config SPIConfig) error
Configure and make the SPI peripheral ready to use.
func (SPI) Transfer
func (spi SPI) Transfer(w byte) (byte, error)
Transfer writes/reads a single byte using the SPI interface. If you need to transfer larger amounts of data, Tx will be faster.
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. This is accomplished by sending zero bits if r is bigger than w or discarding the incoming data if w is bigger than r.
type SPIConfig
type SPIConfig struct {
Frequency uint32
SCK Pin
SDO Pin
SDI Pin
LSBFirst bool
Mode uint8
}
SPIConfig configures a SPI peripheral on the ESP32. Make sure to set at least SCK, SDO and SDI (possibly to NoPin if not in use). The default for LSBFirst (false) and Mode (0) are good for most applications. The frequency defaults to 1MHz if not set but can be configured up to 40MHz. Possible values are 40MHz and integer divisions from 40MHz such as 20MHz, 13.3MHz, 10MHz, 8MHz, etc.
type UART
type UART struct {
Bus *esp.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 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.