-
Notifications
You must be signed in to change notification settings - Fork 9
/
rcpwmgen.vhd
106 lines (102 loc) · 3.85 KB
/
rcpwmgen.vhd
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.std_logic_unsigned.all;
use ieee.math_real.all;
--
-- Copyright (C) 2007, Peter C. Wallace, Mesa Electronics
-- http://www.mesanet.com
--
-- This program is is licensed under a disjunctive dual license giving you
-- the choice of one of the two following sets of free software/open source
-- licensing terms:
--
-- * GNU General Public License (GPL), version 2.0 or later
-- * 3-clause BSD License
--
--
-- The GNU GPL License:
--
-- This program is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; either version 2 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
--
--
-- The 3-clause BSD License:
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
--
-- * Redistributions of source code must retain the above copyright
-- notice, this list of conditions and the following disclaimer.
--
-- * Redistributions in binary form must reproduce the above
-- copyright notice, this list of conditions and the following
-- disclaimer in the documentation and/or other materials
-- provided with the distribution.
--
-- * Neither the name of Mesa Electronics nor the names of its
-- contributors may be used to endorse or promote products
-- derived from this software without specific prior written
-- permission.
--
--
-- Disclaimer:
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
-- FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
-- COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-- INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
-- BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-- CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-- LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
-- ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-- POSSIBILITY OF SUCH DAMAGE.
--
entity rcpwmgen is
port ( clk : in std_logic;
ibus : in std_logic_vector (16 downto 0);
loadwidth : in std_logic;
ratein: in std_logic;
pwmout : out std_logic);
end rcpwmgen;
architecture Behavioral of rcpwmgen is
signal width: std_logic_vector(16 downto 0) := "00000000000000000";
signal count: std_logic_vector(16 downto 0);
alias countmsb: std_logic is count(16);
signal prescale: std_logic_vector(3 downto 0);
begin
arcpwmgen: process (clk,count,prescale)
begin
if rising_edge(clk) then
prescale <= prescale -1;
if prescale = 0 then
if countmsb= '0' then
count <= count -1;
end if;
end if;
if ratein = '1' then
count <= width;
prescale <= x"F"; -- sync prescale with rategen
end if;
if loadwidth = '1' then
width <= ibus(16 downto 0);
end if;
end if; -- clk
pwmout <= not countmsb;
end process;
end Behavioral;