From 68ccc8ed8f4eaa6b5241c4c5e1abee97494e7809 Mon Sep 17 00:00:00 2001
From: Tristan Gingold <tristan.gingold@cern.ch>
Date: Tue, 3 Mar 2020 11:44:27 +0100
Subject: [PATCH] gc_pulse_synchronizer2: add comments.
---
modules/common/gc_pulse_synchronizer2.vhd | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/modules/common/gc_pulse_synchronizer2.vhd b/modules/common/gc_pulse_synchronizer2.vhd
index 46120c19..4a67d185 100644
--- a/modules/common/gc_pulse_synchronizer2.vhd
+++ b/modules/common/gc_pulse_synchronizer2.vhd
@@ -89,12 +89,18 @@ begin -- rtl
d_ack_d0 <= d_ack;
if ready = '1' and d_p_i = '1' and d_p_d0 = '0'then
+ -- Incoming pulse detected and the system is ready.
+ -- Transfer it.
in_ext <= '1';
+ -- Clear ack and ready!
d_ack <= '0';
ready <= '0';
elsif in_ext = '1' and out_feedback = '1' then
+ -- Pulse has been transfered, clear the input.
in_ext <= '0';
elsif in_ext = '0' and out_feedback = '0' then
+ -- Clear transfered. Done.
+ -- This is also the steady state.
d_ack <= '1';
ready <= '1';
end if;
--
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