Hi SimonThere is one use model you must take care with. If you do a directive type transaction - one that interacts with the model but does nothing on the interface it still must have time pass or the ack signaling will fail due to cancelations. See the signal errors directive in the book. In the more recent books it shows 'wait until rising_edge (clk);' however a 'wait for 0 ns ;' is sufficient Jim
Sent from my Sprint Samsung Galaxy Note5. -------- Original message --------From: Simon Thijs de Feber <st.de.fe...@gmail.com> Date: 10/10/16 12:44 AM (GMT-08:00) To: GHDL discuss list <ghdl-discuss@gna.org> Subject: SPAM: Re: [Ghdl-discuss] Handshaking For some stupid reason I am not able to replicate the error anymore.I have since changed my code to make it work and proceed. It seems these changes had positive effect on the behaviour :( @Rene These are the procedures : [code] procedure request_transaction ( signal rdy : out std_logic; signal ack : in std_logic ) is begin -- Record contains new xaction rdy <= '1'; -- Ack = '0', model has started wait until ack = '0'; -- Remove xaction request rdy <= '0'; -- Model executes xaction -- -- Wait for xaction done wait until ack = '1'; end procedure request_transaction; procedure wait_for_transaction ( signal rdy : in std_logic; signal ack : out std_logic ) is variable ack_time : time; begin -- Done ack <= '1'; ack_time := now; -- Find start of xaction if (rdy /= '1') then wait until rdy = '1'; else wait for 0 ns; end if; -- Model is active and has taken over contents of record ack <= '0'; end procedure wait_for_transaction; [/code] Basic idea behind it is to use transactions and handshake via these 2 procedures. best regards, Simon
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