• SPI_LAST: default if not specified the SS pin returns to high after one byte has been transferred.

(:cell:) (Optional, Arduino Due only)

the byte read from the bus.

Extended method for Arduino Due
If you specify one of the Arduino Due's Slave Select (SS) pin in the call to SPI.transfer(), the specified pin is activated (pulled low) before the transfer occurs and deactivated (pulled high) when the transfer is finished.

You can use an additional SPI_CONTINUE or SPI_LAST parameter to manage the Slave Select line after the transfer. SPI_CONTINUE keeps the specified SS pin active (low) after the transfer to allow the send of additional bytes via the transfer() function in the same SPI transaction. The last byte to be transferred should be accompanied by the SPI_LAST parameter. By default, if you don't specify a third parameter, SPI_LAST is used. When a transfer is complete with SPI_LAST, the slave select pin returns inactive (high).

More info on extended methods: Due Extended SPI usage

(:cellnr width=400px:) SPI.transfer(slaveSelectPin, val) (:cell:) (Arduino Due only)

(:cell width=240px:) slave device SS pin

• SPI_LAST: the SS pin returns to high after one byte has been transferred.

• SPI_CONTINUE: keeps the SS pin low, allowing a subsequent byte transfer.

Arduino Due
A slave select pin on the Due allows several devices to share the SPI connection. If a slave select pin is specified in the call to SPI.transfer(), only the specified pin is pulled low before the transfer occurs.

The SPI_CONTINUE and SPI_LAST parameters are used to manage the Slave Select line. SPI_CONTINUE keeps the specified SS pin low after transmitting a byte, enabling the Due to send additional bytes via the transfer() function without terminating the connection. The last byte to be transferred should be accompanied by the SPI_LAST parameter.

By default, the value is SPI_LAST, because it is common for SPI devices to send only one byte at a time. When a transfer is complete with SPI_LAST, the slave select pin returns to high.

A slave select pin allows several devices to share the SPI connection. It is connected to the slave select or chip select pin of an SPI device. If a slave select pin is specified in the call to transfer(), the pin is pulled low (activating the relevant SPI device) before the transfer occurs.

The SPI_CONTINUE and SPI_LAST parameters are used to manage the Slave Select line, that can be kept at a low level using the SPI_CONTINUE parameter. Keeping selected the slave device the Due is able to use subsequent instances of the transfer() function, until the last byte to be transferred that must be accompained by the SPI_LAST parameter. If you don't specify the parameter by default the value is SPI_LAST, because is most common for SPI devices to send one byte per time. The Slave Select pin returns to the high level when the transfer is completed.

• SPI_CONTINUE: keeping low the SS pin allowing another subsequent byte transfer.
• SPI_LAST: the SS pin returns to high level after one byte has been transferred.

A slave select pin allows several devices to share the SPI connection. It is connected to the slave select or chip select pin of an SPI device. If a slave select pin is specified in the call to transfer(), the pin is pulled low (activating the relevant SPI device) before the transfer occurs

Optional, if omitted defaults to pin 52

• SPI_CONTINUE: this parameter keep low the SS pin allowing another subsequent byte transfer.
• SPI_LAST: tell to the SPI interface that is the last one byte to be transferred then the SS pin can return to the high level.

Optional, if omitted defaults to SPI_LAST

(:table border=0 cellpadding=5 cellspacing=0 width=80%:) (:cell width=400px:) SPI.transfer(val) (:cellnr width=400px:) SPI.transfer(slaveSelectPin, val, transferMode) (:cell:) (Arduino Due only) (:cellnr width=400px:) SPI.transfer(val, transferMode) (:cell:) (Arduino Due only) (:tableend:)

(:table border=0 cellpadding=5 cellspacing=0 width=80%:) (:cell width=150px:) val: (:cell width=240px:) the byte to send out over the bus (:cellnr width=150px:) slaveSelectPin: (:cell width=240px:) slave device SS pin
If omitted will be loaded the default SS pin value that is the 52 (:cell:)(Arduino Due only) (:cellnr width=150px:) transferMode: (:cell width=240px:)

• SPI_CONTINUE
• SPI_LAST

If omitted will be loaded the default that is SPI_LAST (:cell:) (Arduino Due only) (:tableend:)

Example

SPI

transfer()

Description

Transfers one byte over the SPI bus, both sending and receiving.

Syntax

SPI.transfer(val)

Parameters

val: the byte to send out over the bus

Returns

the byte read from the bus

Example