X-Git-Url: https://rtime.felk.cvut.cz/gitweb/fpga/rpi-motor-control.git/blobdiff_plain/a878f480354c01ccb7c4b670638cfdc738902c0c..ee6653b06cc0c19947e2ad3cd675a8e4121c00c6:/pmsm-control/cnt_div.vhdl

diff --git a/pmsm-control/cnt_div.vhdl b/pmsm-control/cnt_div.vhdl
new file mode 100644
index 0000000..e65e562
--- /dev/null
+++ b/pmsm-control/cnt_div.vhdl
@@ -0,0 +1,62 @@
+--
+-- * Counter - divider *
+--
+-- part of LXPWR motion control board (c) PiKRON Ltd
+-- idea by Pavel Pisa PiKRON Ltd <ppisa@pikron.com>
+--
+-- license: BSD
+--
+-- This file is used in "RPI PMS motor control" as frequency divider - divides by 6
+
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity cnt_div is
+	generic (
+		cnt_width_g : natural := 4
+	);
+	port
+	(
+		clk_i     : in std_logic;				--clk to divide
+		en_i      : in std_logic;				--enable bit?
+		reset_i   : in std_logic;				--asynch. reset
+		ratio_i   : in std_logic_vector(cnt_width_g-1 downto 0);--initial value
+		q_out_o   : out std_logic				--generates puls when counter underflows
+	);
+end cnt_div;
+
+architecture behavioral of cnt_div is
+	signal cnt_val_s : natural range 0 to (2**cnt_width_g - 1);	--counter value before DFF
+	signal cnt_val_r : natural range 0 to (2**cnt_width_g - 1);	--counter value after DFF
+begin
+
+comb: process (reset_i, en_i, ratio_i, cnt_val_r)
+	begin
+		if reset_i = '1' then --reset detection
+			cnt_val_s <= to_integer(unsigned(ratio_i));  	--set initial value
+			q_out_o   <= '0';				--reset output	
+		else
+			if en_i = '0' then				--stop-state
+				cnt_val_s <= cnt_val_r;			--hold the value
+				q_out_o   <= '0';			--reset output
+			else
+				if cnt_val_r <= 1 then			--counter underflows
+					cnt_val_s <= to_integer(unsigned(ratio_i)); --set initial value
+					q_out_o   <= '1';		--set output
+				else
+					cnt_val_s <= cnt_val_r - 1;	--decrement counter
+					q_out_o   <= '0';		--reset output
+				end if;
+			end if;
+		end if;
+	end process;
+
+seq: process
+	begin
+		wait until clk_i'event and clk_i = '1';
+		cnt_val_r <= cnt_val_s;
+	end process;
+
+end behavioral;
+