pulse leds set to +ve or -ve logic depending on the version of the board

78e79105 · Denia Bouhired-Ferrag · c2634651 · 78e79105
Commit 78e79105 authored Oct 12, 2017 by Denia Bouhired-Ferrag
Show whitespace changes
Inline Side-by-side

Showing with 14 additions and 5 deletions

conv_ttl_rs485.vhd top/conv_ttl_rs485.vhd +14 -5

No files found.
--- a/top/conv_ttl_rs485.vhd
+++ b/top/conv_ttl_rs485.vhd
@@ -357,15 +357,16 @@ begin
      -- Glitch filter active-low enable signal
      gf_en_n_i               => sw_gp_n_i(0),
      
-      -- Burst mode enable signal. Mode disabled for all versions of board
+      -- Burst mode enable signal. Disabled in conv-ttl-rs485
      burst_en_n_i            => '1',
      
    -- Pulse width selection, port low means 250ns, high means 1.2us.  
    -- Switch to determine short or long pulse mode.
    -- ON switch means SHORT 250ns pulse repetition with max frequency 2MHz
    -- OFF switch means LONG 1.2us pulse repetition with max freq ~104kHz
+    -- In conv-ttl-rs485 this switch is not meaningful
    
-      pulse_width_sel_n_i     => '1',
+      pulse_width_sel_n_i     => '0',
      
      -- Channel enable
      global_ch_oen_o         => global_oen_o,
@@ -473,9 +474,17 @@ begin
  rs485_o <= pulse_out;

  -- LED outputs
-  led_front_n_o <= not led_pulse;
-  led_front_inv_n_o <= not led_inv_pulse;
-  led_rear_n_o  <= not led_pulse;
+  -- Boards earlier than v4 do not use -ve logic for LEDs.
+  -- For these LED pulse signals are still in +ve logic.  
+  
+  led_front_n_o <= led_pulse when pcbrev_i (5 downto 0) = "000000"
+                    else not led_pulse;
+  
+  led_front_inv_n_o <= led_inv_pulse when pcbrev_i (5 downto 0) = "000000"
+                    else not led_inv_pulse;
+  
+  led_rear_n_o  <= led_pulse when pcbrev_i (5 downto 0) = "000000"
+                    else not led_pulse;

  -- INV-TTL outputs
  inv_pulse_in_n <= inv_n_i;