vme_bus: don't go to CHECK_TRANSFER_TYPE if DS inactive, causes an infinite loop

ffa531dc · Tomasz Wlostowski · dbf0b46b · ffa531dc
Commit ffa531dc authored Feb 11, 2020 by Tomasz Wlostowski
Hide whitespace changes
Inline Side-by-side

Showing with 3 additions and 2 deletions

vme_bus.vhd hdl/rtl/vme_bus.vhd +3 -2

No files found.
--- a/hdl/rtl/vme_bus.vhd
+++ b/hdl/rtl/vme_bus.vhd
@@ -268,7 +268,7 @@ begin
    variable addr_word_incr : natural range 0 to 7;
  begin
    if rising_edge(clk_i) then
-      if rst_n_i = '0' or vme_as_n_i = '1' then
+      if rst_n_i = '0' or vme_as_n_i /= '0' then
        -- FSM reset after power up,
        -- software reset, manually reset,
        -- on rising edge of AS.
@@ -297,6 +297,7 @@ begin

        s_ADDRlatched    <= (others => '0');
        s_AMlatched      <= (others => '0');
+        s_DSlatched_n <= (others => '1');

        s_vme_addr_reg   <= (others => '0');
        s_vme_addr_dir   <= '0';
@@ -459,7 +460,7 @@ begin
                -- MBLT: ack address.
                -- (Data are also read but discarded).
                s_mainFSMstate <= DTACK_LOW;
-              else
+              elsif s_DSlatched_n /= "11" then
                s_mainFSMstate <= CHECK_TRANSFER_TYPE;
              end if;