A SPI Master, used for communicating with SPI slave devices. More...

#include <SPI.h>

Public Member Functions
	SPI (PinName mosi, PinName miso, PinName sclk, PinName ssel=NC)
	Create a SPI master connected to the specified pins.
void	format (int bits, int mode=0)
	Configure the data transmission format.
void	frequency (int hz=1000000)
	Set the spi bus clock frequency.
virtual int	write (int value)
	Write to the SPI Slave and return the response.
template<typename Type >
int	transfer (const Type tx_buffer, int tx_length, Type rx_buffer, int rx_length, const event_callback_t &callback, int event=SPI_EVENT_COMPLETE)
	Start non-blocking SPI transfer using 8bit buffers.
void	abort_transfer ()
	Abort the on-going SPI transfer, and continue with transfer's in the queue if any.
void	clear_transfer_buffer ()
	Clear the transaction buffer.
void	abort_all_transfers ()
	Clear the transaction buffer and abort on-going transfer.
int	set_dma_usage (DMAUsage usage)
	Configure DMA usage suggestion for non-blocking transfers.
Protected Member Functions
void	irq_handler_asynch (void)
	SPI IRQ handler.
int	transfer (const void tx_buffer, int tx_length, void rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event)
	Common transfer method.
int	queue_transfer (const void tx_buffer, int tx_length, void rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event)
void	start_transfer (const void tx_buffer, int tx_length, void rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event)
	Configures a callback, spi peripheral and initiate a new transfer.
void	start_transaction (transaction_t *data)
	Start a new transaction.
void	dequeue_transaction ()
	Dequeue a transaction.

Detailed Description

A SPI Master, used for communicating with SPI slave devices.

The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz

Most SPI devices will also require Chip Select and Reset signals. These can be controlled using <DigitalOut> pins

Example:

 // Send a byte to a SPI slave, and record the response

 #include "mbed.h"

 // hardware ssel (where applicable)
 //SPI device(p5, p6, p7, p8); // mosi, miso, sclk, ssel

 // software ssel
 SPI device(p5, p6, p7); // mosi, miso, sclk
 DigitalOut cs(p8); // ssel

 int main() {
     // hardware ssel (where applicable)
     //int response = device.write(0xFF);

     // software ssel
     cs = 0;
     int response = device.write(0xFF);
     cs = 1;
 }

Definition at line 66 of file SPI.h.

Constructor & Destructor Documentation

SPI	(	PinName	mosi,
		PinName	miso,
		PinName	sclk,
		PinName	ssel = `NC`
	)

Create a SPI master connected to the specified pins.

mosi or miso can be specfied as NC if not used

Parameters:

mosi	SPI Master Out, Slave In pin
miso	SPI Master In, Slave Out pin
sclk	SPI Clock pin
ssel	SPI chip select pin

Member Function Documentation

void abort_all_transfers ( )

Clear the transaction buffer and abort on-going transfer.

void abort_transfer ( )

Abort the on-going SPI transfer, and continue with transfer's in the queue if any.

void clear_transfer_buffer ( )

Clear the transaction buffer.

void dequeue_transaction ( ) [protected]

Dequeue a transaction.

void format	(	int	bits,
		int	mode = `0`
	)

Configure the data transmission format.

Parameters:

bits	Number of bits per SPI frame (4 - 16)
mode	Clock polarity and phase mode (0 - 3)

 mode | POL PHA
 -----+--------
   0  |  0   0
   1  |  0   1
   2  |  1   0
   3  |  1   1

void frequency ( int hz = 1000000 )

Set the spi bus clock frequency.

Parameters:

hz	SCLK frequency in hz (default = 1MHz)

void irq_handler_asynch ( void ) [protected]

SPI IRQ handler.

int queue_transfer	(	const void *	tx_buffer,
		int	tx_length,
		void *	rx_buffer,
		int	rx_length,
		unsigned char	bit_width,
		const event_callback_t &	callback,
		int	event
	)		`[protected]`

Parameters:

tx_buffer	The TX buffer with data to be transfered. If NULL is passed, the default SPI value is sent
tx_length	The length of TX buffer in bytes
rx_buffer	The RX buffer which is used for received data. If NULL is passed, received data are ignored
rx_length	The length of RX buffer in bytes
bit_width	The buffers element width
callback	The event callback function
event	The logical OR of events to modify

Returns:: Zero if a transfer was added to the queue, or -1 if the queue is full

int set_dma_usage ( DMAUsage usage )

Configure DMA usage suggestion for non-blocking transfers.

Parameters:

usage The usage DMA hint for peripheral

Returns:: Zero if the usage was set, -1 if a transaction is on-going

void start_transaction ( transaction_t * data ) [protected]

Start a new transaction.

Parameters:

data	Transaction data

void start_transfer	(	const void *	tx_buffer,
		int	tx_length,
		void *	rx_buffer,
		int	rx_length,
		unsigned char	bit_width,
		const event_callback_t &	callback,
		int	event
	)		`[protected]`

Configures a callback, spi peripheral and initiate a new transfer.

Parameters:

tx_buffer	The TX buffer with data to be transfered. If NULL is passed, the default SPI value is sent
tx_length	The length of TX buffer in bytes
rx_buffer	The RX buffer which is used for received data. If NULL is passed, received data are ignored
rx_length	The length of RX buffer in bytes
bit_width	The buffers element width
callback	The event callback function
event	The logical OR of events to modify

int transfer	(	const Type *	tx_buffer,
		int	tx_length,
		Type *	rx_buffer,
		int	rx_length,
		const event_callback_t &	callback,
		int	event = `SPI_EVENT_COMPLETE`
	)

Start non-blocking SPI transfer using 8bit buffers.

Parameters:

tx_buffer	The TX buffer with data to be transfered. If NULL is passed, the default SPI value is sent
tx_length	The length of TX buffer in bytes
rx_buffer	The RX buffer which is used for received data. If NULL is passed, received data are ignored
rx_length	The length of RX buffer in bytes
callback	The event callback function
event	The logical OR of events to modify. Look at spi hal header file for SPI events.

Returns:: Zero if the transfer has started, or -1 if SPI peripheral is busy

Definition at line 127 of file SPI.h.

int transfer	(	const void *	tx_buffer,
		int	tx_length,
		void *	rx_buffer,
		int	rx_length,
		unsigned char	bit_width,
		const event_callback_t &	callback,
		int	event
	)		`[protected]`

Common transfer method.

Parameters:

tx_buffer	The TX buffer with data to be transfered. If NULL is passed, the default SPI value is sent
tx_length	The length of TX buffer in bytes
rx_buffer	The RX buffer which is used for received data. If NULL is passed, received data are ignored
rx_length	The length of RX buffer in bytes
bit_width	The buffers element width
callback	The event callback function
event	The logical OR of events to modify

Returns:: Zero if the transfer has started or was added to the queue, or -1 if SPI peripheral is busy/buffer is full

virtual int write ( int value ) [virtual]

Write to the SPI Slave and return the response.

Parameters:

value Data to be sent to the SPI slave

Returns:: Response from the SPI slave

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	31 Jan 2018
Imports:	8
Forks:	0
Commits:	16
Dependents:	0
Dependencies:	2
Followers:	3

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