Class SPISettings

SPISettings Class

Syntax

class SPISettings

Members

Public Constructors
SPISettings::SPISettings	Create a SPISettings object and set SPI clock speed, bit order and data mode

SPISettings::SPISettings

Description

Construct an object and configure SPI parameters — clock speed, bit order and data mode to the preferred default value.

Syntax

SPISettings(uint32_t clock, BitOrder bitOrder, uint8_t dataMode)

Parameters

clock: SPI clock speed in Hz. Default value is 4000000.

bitOrder: The bit order of transmitting command/address/data. Default value is MSBFIRST.

MSBFIRST (MSB: Most Significant Bit)
LSBFIRST (LSB: Least Significant Bit)

dataMode: SPI has four modes that correspond to the four possible clocking configurations. Default value is SPI_MODE0.

SPI_MODE0, SPI_MODE1, SPI_MODE2, SPI_MODE3

Example Code

NA

Note

This class seldom used alone, it is always used with beginTransaction() as a parameter in SPIClass. “SPI.h” must be included to use the class function.

SPIClass Class

Description

A class of SPI implementation for Ameba.

Syntax

class SPIClass

Members

Public Constructors
SPIClass::SPIClass	Constructs an SPI object
Public Methods
SPIClass::begin	Initialise SPI pins on Ameba board
SPIClass::transfer	Transfer data through SPI
SPIClass::transfer16	Transfer data of 16-bits through SPI
SPIClass::beginTransaction	Set slave select pin and SPI initial settings
SPIClass::endTransaction	Stop SPI transaction
SPIClass::setBitOrder	Set bit order to either MSB first or LSB first
SPIClass::setDataMode	Set data mode
SPIClass::setClockDivider	Set to correct clock speed (no effect on Ameba)
SPIClass::setDefaultFrequency	Set default SPI frequency
SPIClass::end	Stop SPI master mode

Construct an SPI object, create a pointer to the SPI master object, and assign “MOSI, MISO, CLK, and SS” to the corresponding pins on Ameba boards. Default SPI tranmission frequency is set to 20,000,000 Hz.

Syntax

SPIClass(void *pSpiObj, int mosi, int miso, int clk, int ss);

Parameters

pSpiObj: A pointer to a structure that stores SPI configuration.

mosi: Master Out, Slave In, a.k.a. Data transmission from a Host to Device.

miso: Master In, Slave Out, a.k.a. Data transmission from a Device to Host.

clk: Serial Clock. Oscillating signal generated by a Host that keeps the transmission of data bits in sync.

ss: Slave Select. Allows a Host to select individual Device(s) connected to the bus in order to send or receive data.

Returns

NA

Example Code

Example: LCD_Screen_ILI9341_TFT

Note

Depending on the Ameba hardware, up to 2 SPIClass objects are created in the spi.cpp library, please use “SPI” for first hardware SPI object and “SPI1” for the second. “SPI.h” must be included to use the class function.

SPIClass::begin

Description

Initialize MOSI, MISO, CLK, and SS pins on Ameba boards, select SPIClass object, and set SPI format and frequency.

Syntax

void begin(void);
void begin(int ss);

Parameters

ss: Slave Select. Allows a Host to select individual Device(s) connected to the bus in order to send or receive data.

Returns

NA

Example Code

NA

Note

This is a required method to use SPI on Ameba. “SPI.h” must be included to use the class function.

SPIClass::transfer

Description

Transfer data through SPI to the slave.

Syntax

byte transfer(byte _pin, uint8_t _data, SPITransferMode _mode = SPI_LAST);
byte transfer(uint8_t _data, SPITransferMode _mode = SPI_LAST);
void transfer(byte _pin, void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST);
void transfer(void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST);

Parameters

_pin: Slave Select pin

_data: Data of 8-bits that transfer from SPI master to the slave

_buf: Data buffer stores data to be written to Tx FIFO

_mode: defines SS pin status after data transmission is finished, available values are SPI_CONTINUE and SPI_LAST. SPI_LAST indicates SS pin will be set to 1 upon data transmission ends.

_count: number of data bytes to be send

Returns

This function either returns NA or data of 8-bits that transferred through SPI master to the slave.

Example Code

NA

Note

“SPI.h” must be included to use the class function.

SPIClass::transfer16

Description

Transfer data of 16-bits through SPI master to the slave.

Syntax

uint16_t transfer16(byte _pin, uint16_t _data, SPITransferMode _mode = SPI_LAST);
uint16_t transfer16(uint16_t _data, SPITransferMode _mode = SPI_LAST);

Parameters

_pin: Slave Select pin

_data: Data of 16-bits that transfer from SPI master to the slave

_mode: defines SS pin status after data transmission is finished, available values are SPI_CONTINUE and SPI_LAST. SPI_LAST indicates SS pin will be set to 1 upon data transmission ends.

Returns

This function returns data of 16-bits being transferred.

Example Code

NA

Note

“SPI.h” must be included to use the class function.

SPIClass::beginTransaction

Description

Set Slave Select pin and initialize SPI with default settings including SPI format, SPI frequency that have been declared in the SPISettings class.

Syntax

void beginTransaction(uint8_t pin, SPISettings settings);
void beginTransaction(SPISettings settings);

Parameters

pin: Slave Select pin

settings: an object of SPISettings class defined previously

Returns

NA

Example Code

NA

Note

Refer to SPISettings class for details of the initial settings. “SPI.h” must be included to use the class function.

SPIClass::endTransaction

Description

Set Slave Select pin to 1 for ending the SPI transaction process.

Syntax

void endTransaction(void);

Parameters

NA

Returns

NA

Example Code

NA

Note

“SPI.h” must be included to use the class function.

SPIClass::setBitOrder

Description

Set bit order to either MSB first or LSB first and set slave select pin.

Syntax

void setBitOrder(uint8_t _pin, BitOrder _bitOrder);
void setBitOrder(BitOrder _order);

Parameters

_pin: slave select

_bitOrder: The bit order of transmitting command/address/data. Default value is MSBFIRST.

MSBFIRST (MSB: Most Significant Bit)
LSBFIRST (LSB: Least Significant Bit)

_order: same as _bitOrder. Default value is MSBFIRST.

Returns

NA

Example Code

NA

Note

“SPI.h” must be included to use the class function.

SPIClass::setDataMode

Description

Set SPI data mode. A total of 4 modes and set slave select pin.

Syntax

void SPIClass::setDataMode(uint8_t _pin, uint8_t _mode);
void SPIClass::setDataMode(uint8_t _mode);

Parameters

_pin: Slave Select pin

_mode: SPI has four modes that correspond to the four possible clocking configurations. Default value is SPI_MODE0.

SPI_MODE0, SPI_MODE1, SPI_MODE2, SPI_MODE3

Returns

NA

Example Code

NA

Note

“SPI.h” must be included to use the class function.

SPIClass::setClockDivider

Description

Set clock divider in order to get correct clock speed.

Syntax

void setClockDivider(uint8_t _pin, uint8_t _divider);
void setClockDivider(uint8_t _div);

Parameters

_pin: Slave Select pin

_divider: clock divider

_div: clock divider

Returns

NA

Example Code

NA

Note

This function does not affect the Ameba board. “SPI.h” must be included to use the class function.

SPIClass::setDefaultFrequency

Description

Set default SPI frequency.

Syntax

void setDefaultFrequency(int _frequency);

Parameters

_frequency: the default SPI frequency in Hz. Default value is 20000000.

Returns

NA

Example Code

Example: LCD_Screen_ILI9341_TFT

Note

Take note that defaultFrequency = _frequency. “SPI.h” must be included to use the class function.

void end(void);

After calling end(), you need to use begin() again to enable SPI function. “SPI.h” must be included to use the class function.