Subversion Repositories quadraturecount

/trunk/QuadratureDecoder.vhd

/trunk/Quadrature.npl Cannot display: file marked as a binary type. svn:mime-type = application/octet-stream

/trunk/Quadrature.npl

trunk/Quadrature.npl Property changes : Added: svn:mime-type ## -0,0 +1 ## +application/octet-stream \ No newline at end of property Index: trunk/QuadratureCounter.vhd =================================================================== --- trunk/QuadratureCounter.vhd (nonexistent) +++ trunk/QuadratureCounter.vhd (revision 2) @@ -0,0 +1,100 @@ +library IEEE; +use IEEE.STD_LOGIC_1164.ALL; +use IEEE.STD_LOGIC_ARITH.ALL; +use IEEE.STD_LOGIC_SIGNED.ALL; + +-- c2003 Franks Development, LLC +-- http://www.franks-development.com +-- !This source is distributed under the terms & conditions specified at opencores.org + +--resource or companion to this code: + -- Xilinx Application note 12 - "Quadrature Phase Decoder" - xapp012.pdf + -- no longer appears on xilinx website (to best of my knowledge), perhaps it has been superceeded? + +--this code was origonally intended for use on Xilinx XPLA3 'coolrunner' CPLD devices +--origonally compiled/synthesized with Xilinx 'Webpack' 5.2 software + +--How we 'talk' to the outside world: +entity QuadratureCounterPorts is + Port ( clock : in std_logic; --system clock, i.e. 10MHz oscillator + QuadA : in std_logic; --first input from quadrature device (i.e. optical disk encoder) + QuadB : in std_logic; --second input from quadrature device (i.e. optical disk encoder) + CounterValue : out std_logic_vector(15 downto 0) --just an example debuggin output + ); +end QuadratureCounterPorts; + +--What we 'do': +architecture QuadratureCounter of QuadratureCounterPorts is + + -- local 'variables' or 'registers' + + --This is the counter for how many quadrature ticks have gone past. + --the size of this counter is dependant on how far you need to count + --it was origonally used with a circular disk encoder having 2048 ticks/revolution + --thus this 16-bit count could hold 2^15 ticks in either direction, or a total + --of 32768/2048 = 16 revolutions in either direction. if the disk + --was turned more than 16 times in a given direction, the counter overflows + --and the origonal location is lost. If you had a linear instead of + --circular encoder that physically could not move more than 2048 ticks, + --then Count would only need to be 11 downto 0, and you could count + --2048 ticks in either direction, regardless of the position of the + --encoder at system bootup. + signal Count : std_logic_vector(15 downto 0); + + --this is the signal from the quadrature logic that it is time to change + --the value of the counter on this clock signal (either + or -) + signal CountEnable : std_logic; + + --should we increment or decrement count? + signal CountDirection : std_logic; + + --where all the 'work' is done: quadraturedecoder.vhd + component QuadratureDecoderPorts + Port ( + clock : in std_logic; + QuadA : in std_logic; + QuadB : in std_logic; + CountDirection : out std_logic; + CountEnable : out std_logic + ); + end component; + + begin --architecture QuadratureCounter + + --instanciate the decoder + iQuadratureDecoder: QuadratureDecoderPorts + port map ( + clock => clock, + QuadA => QuadA, + QuadB => QuadB, + CountDirection => CountDirection, + CountEnable => CountEnable + ); + + + -- do our actual work every clock cycle + process(clock) + begin + + --keep track of the counter + if ( (clock'event) and (clock = '1') ) then + + if (CountEnable = '1') then + + if (CountDirection = '1') then Count <= Count + "0000000000000001"; end if; + if (CountDirection = '0') then Count <= Count - "0000000000000001"; end if; + + end if; + + end if; --clock'event + + --!!!!!!!!!!!INSERT SOMETHING USEFULL HERE!!!!!!!!!!! + --This is where you do actual work based on the value of the counter + --for instance, I will just output the value of the counter + --led's on an output like this are very useful - you can see the top + --bits light when moved backwards from initial position (count goes negative) + CounterValue <= Count; + + end process; --(clock) + +end QuadratureCounter;