From ddab1a2d21f4682c48f7ccc4ef1e3eb465e73f71 Mon Sep 17 00:00:00 2001
From: Alexander Oh <oh.a@gmx.at>
Date: Tue, 25 May 2010 03:49:54 +0200
Subject: [PATCH] small bugfixes that resolve signal instabilities where needed

---
 src/beh_pc_communication_tb.vhd | 16 +++++++++++++---
 src/pc_communication.vhd        | 15 ++++++++++-----
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/beh_pc_communication_tb.vhd b/src/beh_pc_communication_tb.vhd
index 4efc777..854e7ee 100644
--- a/src/beh_pc_communication_tb.vhd
+++ b/src/beh_pc_communication_tb.vhd
@@ -66,29 +66,39 @@ begin
 		file f : byte_file_type open read_mode is "../../src/pc_communication.test";
 		variable rb : hbyte;
 	begin
+		d_done <= '0';
 		wait until rising_edge(d_get);
 		assert not endfile(f) report "test beendet" severity failure;
 		read(f, rb);
 		wait for 30 ns;
 		d_char <= rb;
 		d_done <= '1';
-		wait for 15 ns;
-		d_done <= '0';
+		wait for 30 ns;
 	end process stub_history;
 
+
+	stub_uart : process
+	begin
+		tx_done <= '0';
+		wait until rising_edge(tx_new);
+		wait for 90 ns;
+		tx_done <= '1';
+		wait for 90 ns;
+	end process stub_uart;
+
 	reset_and_button : process
 	begin
 		-- init & reset
 		-- we only simulate pressing of button a by now!
 		sys_res_n <= '0';
 		btn_a <= '0';
-		d_done <= '0';
 		tx_data <= "00000000";
 		rx_data <= "00000000";
 		d_zeile <= "0000000";
 		d_spalte <= "0000000";
 		tx_new <= '0';
 		tx_done <= '0';
+		rx_new <= '0';
 		
 		wait for 90 ns;
 		sys_res_n <= '1';
diff --git a/src/pc_communication.vhd b/src/pc_communication.vhd
index 53ca215..3251284 100644
--- a/src/pc_communication.vhd
+++ b/src/pc_communication.vhd
@@ -36,6 +36,7 @@ architecture beh of pc_communication is
 	signal zeile , zeile_next : hzeile;
 	signal spalte_up, spalte_up_next : std_logic;
 	signal get, get_next : std_logic;
+	signal new_i, new_i_next : std_logic;
 
 	signal char, char_next : hbyte;
 	signal char_en : std_logic;
@@ -48,6 +49,8 @@ begin
 	d_zeile <= zeile;
 	d_spalte <= spalte;
 	d_get <= get;
+	char_next <= d_char;
+	tx_new <= new_i;
 
 	sync: process (sys_clk, sys_res_n)
 	begin
@@ -59,7 +62,7 @@ begin
 			zeile <= "0000000";
 			zeile_next <= "0000000";
 			get <= '0';
-			tx_new <= '0';
+			new_i <= '0';
 			tx_data <= "00000000";
 		elsif rising_edge(sys_clk) then
 			push_history <= push_history_next;
@@ -67,8 +70,9 @@ begin
 			zeile <= zeile_next;
 			state <= state_next;
 			get <= get_next;
+			new_i <= new_i_next;
 			if (char_en = '1') then
-				state <= state_next;
+				char <= char_next;
 			end if;
 		end if;
 	end process sync;
@@ -111,9 +115,10 @@ begin
 	output_pc : process (state, zeile, spalte, char)
 	begin
 		get_next <= '0';
+		new_i_next <= '0';
 		spalte_next <= "0000000";
 		zeile_next <= "0000000";
-		case state is 
+		case state is
 			when IDLE =>
 				null;
 			when FETCH =>
@@ -122,7 +127,7 @@ begin
 			when FORWARD =>
 				char_en <= '0';
 				tx_data <= char;
-				tx_new <= '1';
+				new_i_next <= '1';
 			when DONE =>
 				null;
 		end case;
@@ -135,7 +140,7 @@ begin
 			when IDLE =>
 				if rx_new = '1' or btn_a = '1' then
 					state_next <= FETCH;
-					char <= d_char; --latch
+					
 				end if;
 			when FETCH =>
 				if (d_done = '1') then
-- 
2.25.1