i2c.vhd

一个用状态机VHDL语言编写的I2C源代码

                        IF (phase2 = '1') THEN
                           scl_xhdl1 <= '0';    
                        END IF;
                     END IF;
                     CASE i2c_state IS
                        WHEN ini =>
                                 CASE inner_state IS
                                    WHEN start =>
                                             IF (phase1 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= '0';    
                                             END IF;
                                             IF ((phase3 AND link) = '1') THEN
                                                inner_state <= first;    
                                                sda_buf <= '1';    
                                                link <= '1';    
                                             END IF;
                                    WHEN first =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= second;    
                                             END IF;
                                    WHEN second =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '1';    
                                                link <= '1';    
                                                inner_state <= third;    
                                             END IF;
                                    WHEN third =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= fourth;    
                                             END IF;
                                    WHEN fourth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= fifth;    
                                             END IF;
                                    WHEN fifth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= sixth;    
                                             END IF;
                                    WHEN sixth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= seventh;    
                                             END IF;
                                    WHEN seventh =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= eighth;    
                                             END IF;
                                    WHEN eighth =>
                                             IF (phase3 = '1') THEN
                                                link <= '0';    
                                                inner_state <= ack;    
                                             END IF;
                                    WHEN ack =>
                                             IF (phase0 = '1') THEN
                                                sda_buf <= sda;    
                                             END IF;
                                             IF (phase1 = '1') THEN
                                                IF (sda_buf = '1') THEN
                                                   main_state <= "00";    
                                                END IF;
                                             END IF;
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(7);    
                                                inner_state <= first;    
                                                i2c_state <= sendaddr;    
                                             END IF;
                                    WHEN OTHERS =>
                                             NULL;
                                    
                                 END CASE;
                        WHEN sendaddr =>
                                 CASE inner_state IS
                                    WHEN first =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(6);    
                                                inner_state <= second;    
                                             END IF;
                                    WHEN second =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(5);    
                                                inner_state <= third;    
                                             END IF;
                                    WHEN third =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(4);    
                                                inner_state <= fourth;    
                                             END IF;
                                    WHEN fourth =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(3);    
                                                inner_state <= fifth;    
                                             END IF;
                                    WHEN fifth =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(2);    
                                                inner_state <= sixth;    
                                             END IF;
                                    WHEN sixth =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(1);    
                                                inner_state <= seventh;    
                                             END IF;
                                    WHEN seventh =>
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= addr(0);    
                                                inner_state <= eighth;    
                                             END IF;
                                    WHEN eighth =>
                                             IF (phase3 = '1') THEN
                                                link <= '0';    
                                                inner_state <= ack;    
                                             END IF;
                                    WHEN ack =>
                                             IF (phase0 = '1') THEN
                                                sda_buf <= sda;    
                                             END IF;
                                             IF (phase1 = '1') THEN
                                                IF (sda_buf = '1') THEN
                                                   main_state <= "00";    
                                                END IF;
                                             END IF;
                                             IF (phase3 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= '1';    
                                                inner_state <= start;    
                                                i2c_state <= read_ini;    
                                             END IF;
                                    WHEN OTHERS =>
                                             NULL;
                                    
                                 END CASE;
                        WHEN read_ini =>
                                 CASE inner_state IS
                                    WHEN start =>
                                             IF (phase1 = '1') THEN
                                                link <= '1';    
                                                sda_buf <= '0';    
                                             END IF;
                                             IF ((phase3 AND link) = '1') THEN
                                                inner_state <= first;    
                                                sda_buf <= '1';    
                                                link <= '1';    
                                             END IF;
                                    WHEN first =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= second;    
                                             END IF;
                                    WHEN second =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '1';    
                                                link <= '1';    
                                                inner_state <= third;    
                                             END IF;
                                    WHEN third =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= fourth;    
                                             END IF;
                                    WHEN fourth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= fifth;    
                                             END IF;
                                    WHEN fifth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= sixth;    
                                             END IF;
                                    WHEN sixth =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '0';    
                                                link <= '1';    
                                                inner_state <= seventh;    
                                             END IF;
                                    WHEN seventh =>
                                             IF (phase3 = '1') THEN
                                                sda_buf <= '1';    
                                                link <= '1';    
                                                inner_state <= eighth;    
                                             END IF;
                                    WHEN eighth =>
                                             IF (phase3 = '1') THEN
                                                link <= '0';    
                                                inner_state <= ack;    
                                             END IF;