Add transferReceive to SPI interface

include/sta/spi_interface.hpp

@@ -31,9 +31,17 @@ namespace sta
 		 * @brief Send data from buffer.
 		 *
 		 * @param buffer    Source buffer
-		 * @param size      Number of bytes in buffer
+		 * @param size      Number of bytes to transfer
 		 */
 		virtual void transfer(const uint8_t * buffer, size_t size) = 0;
+		/**
+		 * @brief Send and receive data simultaneously.
+		 *
+		 * @param txBuffer  Send buffer
+		 * @param rxBuffer  Receive buffer
+		 * @param size      Number of bytes to transfer
+		 */
+		virtual void transfer(const uint8_t * txBuffer, uint8_t * rxBuffer, size_t size) = 0;
 
 		/**
 		 * @brief Send two bytes of data.