From d468aaedba533b473ac713e09a5dae9f5e9e849f Mon Sep 17 00:00:00 2001
From: Vladimir Burian <buriavl2@fel.cvut.cz>
Date: Sun, 1 May 2011 20:36:52 +0200
Subject: [PATCH] Error in MCU external data bus multiplexer

---
 msp_motion.vhd | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/msp_motion.vhd b/msp_motion.vhd
index 1542c0d..2d2f3f4 100644
--- a/msp_motion.vhd
+++ b/msp_motion.vhd
@@ -165,10 +165,9 @@ begin
 
   -- External data bus address decoder and data multiplexer.
   ------------------------------------------------------------------------------
-  -- This statement leads to priority encoder (which should be avoided), but for
-  -- a small mux it doesn't matter and it's better readable.
-  dmem_dout <= DPA_DAT_O when DPA_SEL = '1' else
-               (others => 'X');
+  -- When connection more memories, be aware that 'dmem_dout' can vary only when
+  -- reading cycle is performed. I.e. mux variable must be registered.
+  dmem_dout <= DPA_DAT_O;
   
   DPA_SEL <= '1' when dmem_addr (11 downto 10) = "00" else '0';
   DPA_STB <= dmem_ce and DPA_SEL;
-- 
2.39.2