Subversion Repositories steppermotordrive

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

-- c2003 Franks Development, LLC

-- http://www.franks-development.com

-- !This source is distributed under the terms & conditions specified at opencores.org

-- 

-- Please see the file "StepperMotorWiring.bmp" for info on connecting 4 & 6 

-- wire motors to your device.  This source should drive either type, though connection

-- to 4-wire motors requires significantly more FET's to buffer outputs.  The

-- circuitry for 6-wire motors is more straightforward.

--

-- Another practical consideration is the threshold voltage of the FET's used to

-- buffer the logic outputs & provide current drive to the motor.  Most power

-- FET's have a threshold voltage in the 5-12V range (or even higher),

-- while logic devices now run in the 3.3V and lower range.  Thus, you must be 

-- careful to choose a FET with a low threshold voltage, or a level-converter must

-- be utilized between the logic output and the gate of the drive FET's.

--

-- One of the most advantageous abilities of stepper motors is the ability to 

-- provide static holding force in any position.  Of course this consumes power

-- and heats the motor up significantly (though steppers are rated to handle this)

-- use of the "static holding" input port will specify this behavior.

entity StepperMotorPorts is

    Port (

                                StepDrive : out std_logic_vector(3 downto 0);

                                clock : in std_logic;

                                Direction : in std_logic;

                                StepEnable : in std_logic --;

                                --ProvideStaticHolding : in std_logic

                );

end StepperMotorPorts;

architecture StepDrive of StepperMotorPorts is

        signal state : std_logic_vector(1 downto 0);

        signal StepCounter : std_logic_vector(31 downto 0);

        constant StepLockOut : std_logic_vector(31 downto 0) := "00000000000000110000110101000000";

begin

        process(clock)

        begin

                if ( (clock'Event) and (clock = '1') ) then

                        StepCounter <= StepCounter + "0000000000000000000000000000001";

                        if (StepCounter >= StepLockOut) then

                                StepCounter <= "00000000000000000000000000000000";

                                StepDrive <= "0000";

                                if (StepEnable = '1') then

                                        if (Direction = '1') then state <= state + "01"; end if;

                                        if (Direction = '0') then state <= state - "01"; end if;

                                        case state is

                                                when "00" =>

                                                        StepDrive <= "1010";

                                                when "01" =>

                                                        StepDrive <= "1001";

                                                when "10" =>

                                                        StepDrive <= "0101";

                                                when "11" =>

                                                        StepDrive <= "0110";

                                                when others =>

                                        end case; --state

                                end if;

                        end if;

                end if;

        end process;

end StepDrive;