[AST] Fix analog out contention
Signed-off-by: Jacob Levy <jacob.levy@opentitan.org>
diff --git a/hw/top_earlgrey/ip/ast/rtl/ast.sv b/hw/top_earlgrey/ip/ast/rtl/ast.sv
index a850928..4be7d90 100644
--- a/hw/top_earlgrey/ip/ast/rtl/ast.sv
+++ b/hw/top_earlgrey/ip/ast/rtl/ast.sv
@@ -562,8 +562,13 @@
assign usb_io_pu_cal_o = {UsbCalibWidth{1'b0}};
//
assign ast2padmux_o = {Ast2PadOutWidth{1'b0}};
-assign ast2pad_t0_ao = 0;
-assign ast2pad_t1_ao = 0;
+`ifndes ANALOGSIM
+assign ast2pad_t0_ao = 1'bz;
+assign ast2pad_t1_ao = 1'bz;
+`else
+assign ast2pad_t0_ao = 0.0;
+assign ast2pad_t1_ao = 0.0;
+`endif
//
assign lc_clk_byp_ack_o = lc_ctrl_pkg::Off;
assign flash_bist_en_o = lc_ctrl_pkg::Off;
