SPISettings Class

SPISettings Class

Description
A class to set SPI parameters.

Syntax
class SPISettings

Members

Public Constructors 
SPISettings::SPISettingsCreate 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. (Default: 4000000(Hz)).
bitOrder: The bit order of transmitting command/address/data. Select between MSBFIRST (MSB: Most Significant Bit) or LSBFIRST (LSB: Least Significant Bit). (Default: MSBFIRST).
dataMode: SPI has four modes: SPI_MODE0, SPI_MODE1, SPI_MODE2, SPI_MODE3 that correspond to the four possible clocking configurations. (Default: SPI_MODE0).

Returns
NA

Example Code
NA

Notes and Warnings
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::SPIClassConstructs an SPI object.
Public Methods 
SPIClass::beginInitialise SPI pins on Ameba board.
SPIClass::transferTransfer data through SPI.
SPIClass::transfer16Transfer data of 16-bits through SPI.
SPIClass::beginTransactionSet slave select pin and SPI initial settings.
SPIClass::endTransactionStop SPI transaction.
SPIClass::setBitOrderSet bit order to either MSB first or LSB first.
SPIClass::setDataModeSet data mode.
SPIClass::setClockDividerSet to correct clock speed (no effect on Ameba).
SPIClass::setDefaultFrequencySet default SPI frequency.
SPIClass::endStop SPI master mode.

SPIClass::SPIClass

Description
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: ILI9341_TFT_LCD_PM2.5
(https://github.com/ambiot/ambd_arduino/blob/dev/Arduino_package/hardware/libraries/SPI/examples/ILI9341_TFT_LCD_PM2.5/ILI9341_TFT_LCD_PM2.5.ino)

Notes and Warnings
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

Notes and Warnings
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

Notes and Warnings
“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

Notes and Warnings
“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

Notes and Warnings
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

Notes and Warnings
“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. Select between MSBFIRST (MSB: Most Significant Bit) or LSBFIRST (LSB: Least Significant Bit). (Default: MSBFIRST).
_order: same as _bitOrder (Default: MSBFIRST).

Returns
NA

Example Code
NA

Notes and Warnings
“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: SPI_MODE0, SPI_MODE1, SPI_MODE2, SPI_MODE3 that correspond to the four possible clocking configurations. (Default: SPI_MODE0).

Returns
NA

Example Code
NA

Notes and Warnings
“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

Notes and Warnings
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 (Default: 20,000,000Hz).

Returns
NA

Example Code
Example: ILI9341_TFT_LCD_PM2.5
(https://github.com/ambiot/ambd_arduino/blob/dev/Arduino_package/hardware/libraries/SPI/examples/ILI9341_TFT_LCD_PM2.5/ILI9341_TFT_LCD_PM2.5.ino)

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

SPIClass::end

Description
This function will finish the communication and release all the allocated resources to stop SPI master mode.

Syntax
void end(void);

Parameters
NA

Returns
NA

Example Code
NA

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

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