A full-duplex data transmission occurs during each SPI clock cycle: the master transmits data to the slave on the MOSI line and the slave receives it; at the same time, the slave transmits data to the master on the MISO line and the master receives it.

To transmit data in a full-duplex mode, use the DlnSpiMasterReadWrite() function (for 8-bit frames) or the DlnSpiMasterReadWrite16() function (for 9-16-bit frames).

Transmission may continue for any number of clock cycles. When complete, the master idles the clock and releases the SS line. Using the DlnSpiMasterReadWriteEx() function, you can configure whether to release SS line after the transmission or to leave it on the low level.

The DlnSpiMasterReadWriteSS() function allows to select the SS line, transmit data and release the SS line. For details, read Connecting Multiple Slave Devices.

In a half-duplex read mode, the slave transmits data on the MISO line and the master receives it. The MOSI line remains inactive.

To receive data in a half-duplex mode, use the DlnSpiMasterReadEx() function. This function allows to configure whether the SS line should be released after the transmission or left on the low level.

In a half-duplex write mode, the master sends data on the MOSI line and the slave receives it. The MISO line remains inactive.

To send data in a half-duplex mode, use the DlnSpiMasterWriteEx() function. This function allows to configure whether the SS line should be released after the transmission or left on the low level.

In a half-duplex mode, the master can send data to multiple slaves simultaneously. For details, read Connecting Multiple Slave Devices.