From: Andreas Neiser <neiser@kph.uni-mainz.de>
Date: Mon, 20 Apr 2015 16:51:12 +0000 (+0200)
Subject: Refine delay
X-Git-Url: https://jspc29.x-matter.uni-frankfurt.de/git/?a=commitdiff_plain;h=1563b1811bf3ea630a9f0191ccf1bbcda062cf82;p=trb3.git

Refine delay
---

diff --git a/ADC/source/adc_processor_cfd_ch.vhd b/ADC/source/adc_processor_cfd_ch.vhd
index 82980b0..85b6b69 100644
--- a/ADC/source/adc_processor_cfd_ch.vhd
+++ b/ADC/source/adc_processor_cfd_ch.vhd
@@ -78,6 +78,9 @@ architecture arch of adc_processor_cfd_ch is
   signal delay_cfd_in  : signed(RESOLUTION_SUB - 1 downto 0) := (others => '0');
   signal delay_cfd_out : signed(RESOLUTION_SUB - 1 downto 0) := (others => '0');
 
+  type delay_sub_t is array (1 downto 0) of subtracted_thresh_t;
+  signal delay_sub     : delay_sub_t                         := (others => subtracted_thresh_t_INIT);
+  
   signal prod, prod_invert : product_thresh_t := product_thresh_t_INIT;
   signal prod_delay        : signed(RESOLUTION_PROD - 1 downto 0) := (others => '0');
 
@@ -200,13 +203,17 @@ begin
     prod_delay   <= resize(prod_delay_s, RESOLUTION_PROD); -- get rid of extra bit again
 
     -- undelayed chain: input is subtracted signal
+    -- however, undelayed chain is also a little bit delayed
+    -- to account for in/out registers of delay chain above
+    delay_sub(0) <= subtracted;
+    delay_sub(1) <= delay_sub(0);
     mult_s      := signed(resize(CONF.CFDMult, CONF.CFDMult'length + 1)); -- add extra zero sign bit
-    prod_s      := mult_s * subtracted.value;
+    prod_s      := mult_s * delay_sub(1).value;
     prod.value  <= resize(prod_s, RESOLUTION_PROD); -- get rid of extra bit again
-    prod.thresh <= subtracted.thresh;
-
+    prod.thresh <= delay_sub(1).thresh;
+    
     -- invert
-    prod_invert.value  <= -prod.value;
+    prod_invert.value  <= -delay_prod.value;
     prod_invert.thresh <= prod.thresh;
 
     -- add both signals to generate the bipolar cfd signal