prbs_sp_distort.vhd: add distortion averaging

In order to prevent our power supplies from saturating (hence
introducing non-linear behaviors, undesirable for our sytem
identification applications), moving average filters were added to
the PRBS-based distortion signal. These filters allow us to smooth the
power supply current setpoint transitions, which lowers the needed PI
control effort, (hopefully) keeping it in the linear operation range.

hdl/modules/fofb_sys_id/cheby/wb_fofb_sys_id_regs.cheby

@@ -97,6 +97,30 @@ memory-map:
 
                       write 0: distortion disabled
                       write 1: distortion enabled
+                - field:
+                    name: sp_distort_mov_avg_num_taps_sel
+                    range: 20-18
+                    description: |
+                      Selects the number of taps for averaging the setpoints
+                      distortion. The number of taps being selected is given by
+                      '2**sp_distort_mov_avg_num_taps_sel'.
+                      NOTE: The maximum value for this field is given by
+                            sp_distort_mov_avg_max_num_taps_sel_cte.
+
+                      write 0x00: set number of taps to 1 (no averaging)
+                      write 0x01: set number of taps to 2
+                      write 0x02: set number of taps to 8
+                      ...
+                      write sp_distort_mov_avg_max_num_taps_sel_cte : set number
+                       of taps to 2**sp_distort_mov_avg_max_num_taps_sel_cte.
+          - reg:
+              name: sp_distort_mov_avg_max_num_taps_sel_cte
+              width: 8
+              access: ro
+              address: next
+              description: |
+                The maximum allowed value for prbs.ctl
+                sp_distort_mov_avg_num_taps_sel field.
           - block:
               name: sp_distort
               description: Interface to setpoints distortion levels regs

hdl/modules/fofb_sys_id/cheby/wb_fofb_sys_id_regs.h

@@ -31,6 +31,13 @@
 #define WB_FOFB_SYS_ID_REGS_PRBS_CTL_LFSR_LENGTH_SHIFT 11
 #define WB_FOFB_SYS_ID_REGS_PRBS_CTL_BPM_POS_DISTORT_EN 0x10000UL
 #define WB_FOFB_SYS_ID_REGS_PRBS_CTL_SP_DISTORT_EN 0x20000UL
+#define WB_FOFB_SYS_ID_REGS_PRBS_CTL_SP_DISTORT_MOV_AVG_NUM_TAPS_SEL_MASK 0x1c0000UL
+#define WB_FOFB_SYS_ID_REGS_PRBS_CTL_SP_DISTORT_MOV_AVG_NUM_TAPS_SEL_SHIFT 18
+
+/* The maximum allowed value for prbs.ctl
+sp_distort_mov_avg_num_taps_sel field.
+ */
+#define WB_FOFB_SYS_ID_REGS_PRBS_SP_DISTORT_MOV_AVG_MAX_NUM_TAPS_SEL_CTE 0x1004UL
 
 /* Interface to setpoints distortion levels regs */
 #define WB_FOFB_SYS_ID_REGS_PRBS_SP_DISTORT 0x1040UL
@@ -98,8 +105,13 @@ struct wb_fofb_sys_id_regs {
  */
     uint32_t ctl;
 
-    /* padding to: 16 words */
-    uint32_t __padding_0[15];
+    /* [0x4]: REG (ro) The maximum allowed value for prbs.ctl
+sp_distort_mov_avg_num_taps_sel field.
+ */
+    uint8_t sp_distort_mov_avg_max_num_taps_sel_cte;
+
+    /* padding to: 64 words */
+    uint8_t __padding_0[59];
 
     /* [0x40]: BLOCK Interface to setpoints distortion levels regs */
     struct sp_distort {

hdl/modules/fofb_sys_id/cheby/wb_fofb_sys_id_regs.vhd

@@ -1,4 +1,4 @@
--- Do not edit.  Generated on Mon May 08 18:02:08 2023 by guilherme.ricioli
+-- Do not edit.  Generated on Sat May 13 12:01:33 2023 by guilherme.ricioli
 -- With Cheby 1.4.0 and these options:
 --  -i wb_fofb_sys_id_regs.cheby --hdl vhdl --gen-hdl wb_fofb_sys_id_regs.vhd --doc html --gen-doc doc/wb_fofb_sys_id_regs.html --gen-c wb_fofb_sys_id_regs.h --consts-style vhdl-ohwr --gen-consts ../../../sim/regs/wb_fofb_sys_id_regs_consts_pkg.vhd
 
@@ -72,6 +72,25 @@ entity wb_fofb_sys_id_regs is
     -- write 1: distortion enabled
 
     prbs_ctl_sp_distort_en_o : out   std_logic;
+    -- Selects the number of taps for averaging the setpoints
+    -- distortion. The number of taps being selected is given by
+    -- '2**sp_distort_mov_avg_num_taps_sel'.
+    -- NOTE: The maximum value for this field is given by
+    --       sp_distort_mov_avg_max_num_taps_sel_cte.
+
+    -- write 0x00: set number of taps to 1 (no averaging)
+    -- write 0x01: set number of taps to 2
+    -- write 0x02: set number of taps to 8
+    -- ...
+    -- write sp_distort_mov_avg_max_num_taps_sel_cte : set number
+    --  of taps to 2**sp_distort_mov_avg_max_num_taps_sel_cte.
+
+    prbs_ctl_sp_distort_mov_avg_num_taps_sel_o : out   std_logic_vector(2 downto 0);
+
+    -- The maximum allowed value for prbs.ctl
+    -- sp_distort_mov_avg_num_taps_sel field.
+
+    prbs_sp_distort_mov_avg_max_num_taps_sel_cte_i : in    std_logic_vector(7 downto 0);
 
     -- Two signed 16-bit distortion levels in RTM-LAMP ADC
     -- counts, one for each PRBS value.
@@ -278,6 +297,7 @@ architecture syn of wb_fofb_sys_id_regs is
   signal prbs_ctl_lfsr_length_reg       : std_logic_vector(4 downto 0);
   signal prbs_ctl_bpm_pos_distort_en_reg : std_logic;
   signal prbs_ctl_sp_distort_en_reg     : std_logic;
+  signal prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg : std_logic_vector(2 downto 0);
   signal prbs_ctl_wreq                  : std_logic;
   signal prbs_ctl_wack                  : std_logic;
   signal prbs_sp_distort_ch_0_levels_level_0_reg : std_logic_vector(15 downto 0);
@@ -418,6 +438,7 @@ begin
   prbs_ctl_lfsr_length_o <= prbs_ctl_lfsr_length_reg;
   prbs_ctl_bpm_pos_distort_en_o <= prbs_ctl_bpm_pos_distort_en_reg;
   prbs_ctl_sp_distort_en_o <= prbs_ctl_sp_distort_en_reg;
+  prbs_ctl_sp_distort_mov_avg_num_taps_sel_o <= prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg;
   process (clk_i) begin
     if rising_edge(clk_i) then
       if rst_n_i = '0' then
@@ -426,6 +447,7 @@ begin
         prbs_ctl_lfsr_length_reg <= "00000";
         prbs_ctl_bpm_pos_distort_en_reg <= '0';
         prbs_ctl_sp_distort_en_reg <= '0';
+        prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg <= "000";
         prbs_ctl_wack <= '0';
       else
         if prbs_ctl_wreq = '1' then
@@ -434,12 +456,15 @@ begin
           prbs_ctl_lfsr_length_reg <= wr_dat_d0(15 downto 11);
           prbs_ctl_bpm_pos_distort_en_reg <= wr_dat_d0(16);
           prbs_ctl_sp_distort_en_reg <= wr_dat_d0(17);
+          prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg <= wr_dat_d0(20 downto 18);
         end if;
         prbs_ctl_wack <= prbs_ctl_wreq;
       end if;
     end if;
   end process;
 
+  -- Register prbs_sp_distort_mov_avg_max_num_taps_sel_cte
+
   -- Register prbs_sp_distort_ch_0_levels
   prbs_sp_distort_ch_0_levels_level_0_o <= prbs_sp_distort_ch_0_levels_level_0_reg;
   prbs_sp_distort_ch_0_levels_level_1_o <= prbs_sp_distort_ch_0_levels_level_1_reg;
@@ -750,6 +775,9 @@ begin
         -- Reg prbs_ctl
         prbs_ctl_wreq <= wr_req_d0;
         wr_ack_int <= prbs_ctl_wack;
+      when "000000001" =>
+        -- Reg prbs_sp_distort_mov_avg_max_num_taps_sel_cte
+        wr_ack_int <= wr_req_d0;
       when "000010000" =>
         -- Reg prbs_sp_distort_ch_0_levels
         prbs_sp_distort_ch_0_levels_wreq <= wr_req_d0;
@@ -811,7 +839,7 @@ begin
   end process;
 
   -- Process for read requests.
-  process (adr_int, rd_req_int, bpm_pos_flatenizer_ctl_base_bpm_id_reg, bpm_pos_flatenizer_max_num_cte_i, prbs_ctl_rst_reg, prbs_ctl_step_duration_reg, prbs_ctl_lfsr_length_reg, prbs_ctl_bpm_pos_distort_en_reg, prbs_ctl_sp_distort_en_reg, prbs_sp_distort_ch_0_levels_level_0_reg, prbs_sp_distort_ch_0_levels_level_1_reg, prbs_sp_distort_ch_1_levels_level_0_reg, prbs_sp_distort_ch_1_levels_level_1_reg, prbs_sp_distort_ch_2_levels_level_0_reg, prbs_sp_distort_ch_2_levels_level_1_reg, prbs_sp_distort_ch_3_levels_level_0_reg, prbs_sp_distort_ch_3_levels_level_1_reg, prbs_sp_distort_ch_4_levels_level_0_reg, prbs_sp_distort_ch_4_levels_level_1_reg, prbs_sp_distort_ch_5_levels_level_0_reg, prbs_sp_distort_ch_5_levels_level_1_reg, prbs_sp_distort_ch_6_levels_level_0_reg, prbs_sp_distort_ch_6_levels_level_1_reg, prbs_sp_distort_ch_7_levels_level_0_reg, prbs_sp_distort_ch_7_levels_level_1_reg, prbs_sp_distort_ch_8_levels_level_0_reg, prbs_sp_distort_ch_8_levels_level_1_reg, prbs_sp_distort_ch_9_levels_level_0_reg, prbs_sp_distort_ch_9_levels_level_1_reg, prbs_sp_distort_ch_10_levels_level_0_reg, prbs_sp_distort_ch_10_levels_level_1_reg, prbs_sp_distort_ch_11_levels_level_0_reg, prbs_sp_distort_ch_11_levels_level_1_reg, prbs_bpm_pos_distort_distort_ram_levels_int_dato, prbs_bpm_pos_distort_distort_ram_levels_rack) begin
+  process (adr_int, rd_req_int, bpm_pos_flatenizer_ctl_base_bpm_id_reg, bpm_pos_flatenizer_max_num_cte_i, prbs_ctl_rst_reg, prbs_ctl_step_duration_reg, prbs_ctl_lfsr_length_reg, prbs_ctl_bpm_pos_distort_en_reg, prbs_ctl_sp_distort_en_reg, prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg, prbs_sp_distort_mov_avg_max_num_taps_sel_cte_i, prbs_sp_distort_ch_0_levels_level_0_reg, prbs_sp_distort_ch_0_levels_level_1_reg, prbs_sp_distort_ch_1_levels_level_0_reg, prbs_sp_distort_ch_1_levels_level_1_reg, prbs_sp_distort_ch_2_levels_level_0_reg, prbs_sp_distort_ch_2_levels_level_1_reg, prbs_sp_distort_ch_3_levels_level_0_reg, prbs_sp_distort_ch_3_levels_level_1_reg, prbs_sp_distort_ch_4_levels_level_0_reg, prbs_sp_distort_ch_4_levels_level_1_reg, prbs_sp_distort_ch_5_levels_level_0_reg, prbs_sp_distort_ch_5_levels_level_1_reg, prbs_sp_distort_ch_6_levels_level_0_reg, prbs_sp_distort_ch_6_levels_level_1_reg, prbs_sp_distort_ch_7_levels_level_0_reg, prbs_sp_distort_ch_7_levels_level_1_reg, prbs_sp_distort_ch_8_levels_level_0_reg, prbs_sp_distort_ch_8_levels_level_1_reg, prbs_sp_distort_ch_9_levels_level_0_reg, prbs_sp_distort_ch_9_levels_level_1_reg, prbs_sp_distort_ch_10_levels_level_0_reg, prbs_sp_distort_ch_10_levels_level_1_reg, prbs_sp_distort_ch_11_levels_level_0_reg, prbs_sp_distort_ch_11_levels_level_1_reg, prbs_bpm_pos_distort_distort_ram_levels_int_dato, prbs_bpm_pos_distort_distort_ram_levels_rack) begin
     -- By default ack read requests
     rd_dat_d0 <= (others => 'X');
     prbs_bpm_pos_distort_distort_ram_levels_rreq <= '0';
@@ -841,7 +869,13 @@ begin
         rd_dat_d0(15 downto 11) <= prbs_ctl_lfsr_length_reg;
         rd_dat_d0(16) <= prbs_ctl_bpm_pos_distort_en_reg;
         rd_dat_d0(17) <= prbs_ctl_sp_distort_en_reg;
-        rd_dat_d0(31 downto 18) <= (others => '0');
+        rd_dat_d0(20 downto 18) <= prbs_ctl_sp_distort_mov_avg_num_taps_sel_reg;
+        rd_dat_d0(31 downto 21) <= (others => '0');
+      when "000000001" =>
+        -- Reg prbs_sp_distort_mov_avg_max_num_taps_sel_cte
+        rd_ack_d0 <= rd_req_int;
+        rd_dat_d0(7 downto 0) <= prbs_sp_distort_mov_avg_max_num_taps_sel_cte_i;
+        rd_dat_d0(31 downto 8) <= (others => '0');
       when "000010000" =>
         -- Reg prbs_sp_distort_ch_0_levels
         rd_ack_d0 <= rd_req_int;

hdl/modules/fofb_sys_id/fofb_sys_id_pkg.vhd

@@ -82,7 +82,8 @@ package fofb_sys_id_pkg is
   component prbs_sp_distort is
     generic (
       g_SP_WIDTH            : natural := 15;
-      g_DISTORT_LEVEL_WIDTH : natural := 16
+      g_DISTORT_LEVEL_WIDTH : natural := 16;
+      g_MAX_ORDER_SEL       : natural := 4
     );
     port (
       clk_i                 : in std_logic;
@@ -96,6 +97,7 @@ package fofb_sys_id_pkg is
       sp_valid_i            : in std_logic;
       distort_level_0_i     : in signed(g_DISTORT_LEVEL_WIDTH-1 downto 0);
       distort_level_1_i     : in signed(g_DISTORT_LEVEL_WIDTH-1 downto 0);
+      order_sel_i           : in natural range 0 to g_MAX_ORDER_SEL := 0;
       distort_sp_o          : out signed(g_SP_WIDTH-1 downto 0);
       distort_sp_valid_o    : out std_logic;
       prbs_o                : out std_logic;

hdl/modules/fofb_sys_id/prbs_sp_distort.vhd

@@ -17,6 +17,7 @@
 -- Date         Version  Author              Description
 -- 2023-04-17   1.0      guilherme.ricioli   Created
 -- 2023-04-19   1.1      guilherme.ricioli   Wrap prbs_gen_for_sys_id
+-- 2023-05-13   1.2      guilherme.ricioli   Add distortion averaging
 --------------------------------------------------------------------------------
 
 library ieee;
@@ -33,7 +34,11 @@ entity prbs_sp_distort is
     g_SP_WIDTH            : natural := 15;
 
     -- Width of distortion levels
-    g_DISTORT_LEVEL_WIDTH : natural := 16
+    g_DISTORT_LEVEL_WIDTH : natural := 16;
+
+    -- Moving average maximum order
+    -- The maximum order being selected is given by '2**g_MAX_ORDER_SEL - 1'
+    g_MAX_ORDER_SEL       : natural := 4
   );
   port (
     -- Clock
@@ -61,6 +66,8 @@ entity prbs_sp_distort is
     prbs_lfsr_length_i    : in natural range 2 to 32 := 32;
 
     -- PRBS iteration signal
+    -- NOTE: The averaged distortion for the new PRBS value will be ready after
+    --       4 clock cycles.
     prbs_valid_i          : in std_logic;
 
     -- Setpoint
@@ -75,6 +82,10 @@ entity prbs_sp_distort is
     -- Distortion level for PRBS value '1'
     distort_level_1_i     : in signed(g_DISTORT_LEVEL_WIDTH-1 downto 0);
 
+    -- Moving average order selector
+    -- The order being selected is given by '2**order_sel_i - 1'
+    order_sel_i           : in natural range 0 to g_MAX_ORDER_SEL := 0;
+
     -- Distorted setpoint
     distort_sp_o          : out signed(g_SP_WIDTH-1 downto 0);
 
@@ -91,13 +102,46 @@ end entity prbs_sp_distort;
 
 architecture beh of prbs_sp_distort is
   signal prbs : std_logic := '0';
+  signal prbs_valid : std_logic := '0';
+  signal distort : signed(g_DISTORT_LEVEL_WIDTH-1 downto 0) := (others => '0');
+  signal distort_valid : std_logic := '0';
+  signal avgd_distort : signed(g_DISTORT_LEVEL_WIDTH-1 downto 0) := (others => '0');
+  signal avgd_distort_valid : std_logic := '0';
+  signal avgd_distort_reg : signed(g_DISTORT_LEVEL_WIDTH-1 downto 0) := (others => '0');
   signal sp_valid_d1 : std_logic := '0';
   -- 1-bit larger than the largest between sp_i and distort_level_{0,1}_i
   -- so to accomodate their sum
   signal distort_sp_aux : signed(maximum(g_SP_WIDTH, g_DISTORT_LEVEL_WIDTH) downto 0);
 begin
+  -- This process drives the PRBS distortion averaging.
+  -- After PRBS iteration, it selects the distortion level (based on PRBS
+  -- value), drives cmp_mov_avg_dyn with it and registers the averaged
+  -- distortion on avgd_distort_reg.
+  -- NOTE: The averaged distortion for a new PRBS value will be ready after 4
+  --       clock cycles:
+  --        1 cc for muxing the distortion levels;
+  --        2 cc for averaging the distortion; and
+  --        1 cc for registering it.
+  p_drive_distort_averaging : process(clk_i) is
+  begin
+    distort_valid <= '0';
+    if prbs_valid = '1' then
+      if prbs = '0' then
+        distort <= distort_level_0_i;
+      else  -- prbs_i = '1'
+        distort <= distort_level_1_i;
+      end if;
+      distort_valid <= '1';
+    elsif avgd_distort_valid = '1' then
+      avgd_distort_reg <= avgd_distort;
+    end if;
+  end process p_drive_distort_averaging;
 
-  process(clk_i) is
+  -- This process adds PRBS averaged distortion to the setpoint.
+  -- NOTE: There's no coordination between this process and
+  --       p_drive_distort_averaging. It simply uses the averaged distortion
+  --       registered on avgd_distort_reg.
+  p_add_avgd_distort : process(clk_i) is
     -- 1-bit larger than the largest between sp_i and distort_level_{0,1}_i
     -- This is done so there's no {over,under}flow on signed '+' operation
     variable v_resized_sp : signed(maximum(g_SP_WIDTH, g_DISTORT_LEVEL_WIDTH) downto 0);
@@ -109,14 +153,10 @@ begin
       else
         v_resized_sp := resize(sp_i, maximum(g_SP_WIDTH, g_DISTORT_LEVEL_WIDTH)+1);
 
-        -- Pipeline stage 1 of 2: sum or bypass PRBS distortion
+        -- Pipeline stage 1 of 2: sum or bypass PRBS averaged distortion
         -- #####################################################################
         if en_distort_i = '1' then
-          if prbs = '0' then
-            distort_sp_aux <= v_resized_sp + distort_level_0_i;
-          else  -- prbs_i = '1'
-            distort_sp_aux <= v_resized_sp + distort_level_1_i;
-          end if;
+          distort_sp_aux <= v_resized_sp + avgd_distort_reg;
         else  -- en_distort_i = '0'
           distort_sp_aux <= v_resized_sp;
         end if;
@@ -131,7 +171,7 @@ begin
         -- #####################################################################
       end if;
     end if;
-  end process;
+  end process p_add_avgd_distort;
 
   cmp_prbs_gen_for_sys_id : prbs_gen_for_sys_id
     port map (
@@ -143,9 +183,25 @@ begin
       valid_i         => prbs_valid_i,
       busy_o          => open,
       prbs_o          => prbs,
-      valid_o         => prbs_valid_o
+      valid_o         => prbs_valid
+    );
+
+  cmp_mov_avg_dyn : mov_avg_dyn
+    generic map (
+      g_MAX_ORDER_SEL => g_MAX_ORDER_SEL,
+      g_DATA_WIDTH    => g_DISTORT_LEVEL_WIDTH
+    )
+    port map (
+      clk_i           => clk_i,
+      rst_n_i         => rst_n_i,
+      order_sel_i     => order_sel_i,
+      data_i          => distort,
+      valid_i         => distort_valid,
+      avgd_data_o     => avgd_distort,
+      valid_o         => avgd_distort_valid
     );
 
   prbs_o <= prbs;
+  prbs_valid_o <= prbs_valid;
 
 end architecture beh;