12004 MAPLDVHDL Synthesis Introduction VHDL Synthesis for High-Reliability Systems 2004 MAPLD International Conference Washington, D.C. September 7, 2004

22004 MAPLDVHDL Synthesis Introduction Seminar Leaders And Practicing Design Engineers Jonathan AlexanderActel Corporation Rod BartoNASA Office of Logic Design Melanie BergBall Aerospace Jeff CotnerNASA Johnson Space Center Marty FraemanApplied Physics Laboratory Rich KatzNASA Office of Logic Design Igor KleynerNASA Office of Logic Design

32004 MAPLDVHDL Synthesis Introduction Training vs. Education The NASA Office of Logic Design works to educate design engineers, not train them. –Training promotes rote responses –Education promotes thinking and the ability to adapt to and cope with new situations. Hence, MAPLD hosts seminars and not training sessions.

42004 MAPLDVHDL Synthesis Introduction Design Seminars The field is complex and dynamic and most definitely not static. Most examples are from or are derived from actual flight designs and are not academic exercises. Many ways to accomplish functions, some better than others, often depending on the situation. Contribute: Discuss the topics presented, disagree with them, present interesting cases you wish to share, and present better ideas. Do not sit there quietly and expect to be treated like a cocker spaniel being trained and drilled to emit Pavlovian responses in response to stimuli (bell for dogs, donuts for engineers).

52004 MAPLDVHDL Synthesis Introduction Material Material will be made available on –CD-ROM –Hardcopy –klabs.org All public domain, you may use the material as you wish.

62004 MAPLDVHDL Synthesis Introduction Barto's Law: Every circuit is considered guilty until proven innocent.

72004 MAPLDVHDL Synthesis Introduction A VHDL Synthesis Issue: Synchronization Circuits

82004 MAPLDVHDL Synthesis Introduction Intended Circuit Synchronizer with Leading Edge Detect

92004 MAPLDVHDL Synthesis Introduction VHDL Code entity EDGE_DETECT_SYNC is generic ( RESET_LEVEL : STD_LOGIC := '1' ); port ( CLK : in STD_LOGIC; RESET : in STD_LOGIC; INPUT : in STD_LOGIC; LED_OUT : out STD_LOGIC; TED_OUT : out STD_LOGIC ); end EDGE_DETECT_SYNC; architecture BEHAVIORAL of EDGE_DETECT_SYNC is signal IN_BETWEEN : STD_LOGIC; signal DATA_OUT : STD_LOGIC; begin FF1 : process(RESET, CLK) begin if (RESET = RESET_LEVEL) then IN_BETWEEN <= '0'; elsif rising_edge(CLK) then IN_BETWEEN <= INPUT; end if; end process; FF2 : process(RESET, CLK) begin if (RESET = RESET_LEVEL) then DATA_OUT <= '0'; elsif rising_edge(CLK) then DATA_OUT <= IN_BETWEEN; end if; end process; LED_OUT <= (not DATA_OUT) and IN_BETWEEN; TED_OUT <= DATA_OUT and (not IN_BETWEEN); end BEHAVIORAL;

MAPLDVHDL Synthesis Introduction Synthesized Circuit Not pleasant to read

MAPLDVHDL Synthesis Introduction Enjoy your seminar!