Don't use tri-state logic for TDO; introduce TDO_EN signal to indicate when TDO is...

[c4m-jtag.git] / rtl / vhdl / c4m_jtag_idblock.vhdl

diff --git a/rtl/vhdl/c4m_jtag_idblock.vhdl b/rtl/vhdl/c4m_jtag_idblock.vhdl
index d4353c1b025dde0435262be9297753f539517587..4c06befd405abc145ed49f45cc87ac59b6c61366 100644 (file)
--- a/rtl/vhdl/c4m_jtag_idblock.vhdl
+++ b/rtl/vhdl/c4m_jtag_idblock.vhdl
@@ -18,6 +18,7 @@ entity c4m_jtag_idblock is
     TCK:        in std_logic;
     TDI:        in std_logic;
     TDO:        out std_logic;
+    TDO_EN:     out std_logic := '0';
 
     -- JTAG state
     STATE:      in TAPSTATE_TYPE;
@@ -65,5 +66,7 @@ begin
 
   EN_TDO <= STATE = Shift and DRSTATE = '1' and (IR = CMD_IDCODE or IR = CMD_BYPASS);
   TDO <= SR_ID(0) when EN_TDO else
-         'Z';
+         '0';
+  TDO_EN <= '1' when EN_TDO else
+            '0';
 end rtl;