+/**
+ * @}
+ * @defgroup Signal Port signalling operations
+ * @{
+ */
+
+/**
+ * Gets the status of the control signals for the specified port.
+ *
+ * The user should allocate a variable of type "enum sp_signal" and pass a
+ * pointer to this variable to receive the result. The result is a bitmask
+ * in which individual signals can be checked by bitwise OR with values of
+ * the sp_signal enum.
+ *
+ * @param port Pointer to port structure.
+ * @param signals Pointer to variable to receive result.
+ *
+ * @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
+ * if an an invalid port or pointer is passed.
+ */
+enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals);
+
+/**
+ * Put the port transmit line into the break state.
+ *
+ * @param port Pointer to port structure.
+ *
+ * @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
+ * if an invalid port is passed.
+ */
+enum sp_return sp_start_break(struct sp_port *port);
+
+/**
+ * Take the port transmit line out of the break state.
+ *
+ * @param port Pointer to port structure.
+ *
+ * @return SP_OK on success, SP_ERR_FAIL on failure, or SP_ERR_ARG
+ * if an invalid port is passed.
+ */
+enum sp_return sp_end_break(struct sp_port *port);
+