documentation stepper motor

7/31/2019 Documentation Stepper Motor

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Content

1. Theory 3

2. Stepper Motor 3

i. Definition 3

ii. Characteristics 3

iii. Working 4

iv. Stepping Modes 6

b. Parallel Port 8

3. The Circuit 11

4. Programming 14

a. The Accessing I/O Ports under NT/2000/XP 14

b. The Program code in VB 15

c. I/O Port Access in Turbo C, Borland C/C++ 19

d. The Program Code in Unix environment In C 19

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THEORY

1. STEPPER MOTOR

2. PARALLEL PORT

1. STEPPER MOTOR

In Theory, a Stepper motor is a marvel in simplicity. It has no brushes, or contacts.

Basically it's a synchronous motor with the magnetic field electronically switched to rotate

the armature magnet around.

Definition

A stepper motor is basically an electromechanical device which converts electrical

pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates

in discrete step increments when electrical command pulses are applied to it in the proper

sequence. The motors rotation has several direct relationships to these applied input pulses.

The sequence of the applied pulses is directly related to the direction of motor shafts

rotation. The speed of the motor shafts rotation is directly related to the frequency of the

input pulses and the length of rotation is directly related to the number of input pulses

applied.

Characteristics:

Holding Torque - Steppers have very good low speed and holding torque.

Steppers are usually rated in terms of their holding force (oz/in) and can even hold a

position (to a lesser degree) without power applied, using magnetic 'detent' torque.

Open loop positioning - Perhaps the most valuable and interesting feature of a

stepper is the ability to position the shaft in fine predictable increments, without need to

query the motor as to its position. Steppers can run 'open-loop' without the need for any

kind of encoder to determine the shaft position. Closed loop systems- systems that feed

back position information, are known as servo systems. Compared to servos, steppers are

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very easy to control; the position of the shaft is guaranteed as long as the torque of the

motor is sufficient for the load, under all its operating conditions.

Load Independent - The rotation speed of a stepper is independent of load,

provided it has sufficient torque to overcome slipping. The higher rpm a stepper motor is

driven, the more torque it needs, so all steppers eventually poop out at some rpm and start

slipping. Slipping is usually a disaster for steppers, because the position of the shaft

becomes unknown. For this reason, software usually keeps the stepping rate within a

maximum top rate. In applications where a known RPM is needed under a varying load,

steppers can be very handy.

Working:

The stepper motor uses the theory of operation for magnets to make the motor shaft

turn a precise distance when a pulse of electricity is provided. You learned previously that

like poles of a magnet repel and unlike poles attract. Figure 1 shows a typical cross-

sectional view of the rotor and stator of a stepper motor. From this diagram you can see

that the stator (stationary winding) has four poles, and the rotor has six poles (three

complete magnets). The rotor will require 12 pulses of electricity to move the 12 steps to

make one complete revolution. Another way to say this is that the rotor will move

precisely 30 for each pulse of electricity that the motor receives. The number of

degrees the rotor will turn when a pulse of electricity is delivered to the motor can be

calculated by dividing the number of degrees in one revolution of the shaft (360) by the

number of poles (north and south) in the rotor. In this stepper motor 360 is divided by 12

to get 30.

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Figure 1. Diagram that shows the position of the six-pole rotor and four-pole

stator of a typical stepper motor

When no power is applied to the motor, the residual magnetism in the rotor magnets

will cause the rotor to detentor align one set of its magnetic poles with the magnetic poles

of one of the stator magnets. This means that the rotor will have 12 possible detent

positions. When the rotor is in a detent position, it will have enough magnetic force to keep

the shaft from moving to the next position. This is what makes the rotor feel like it is

clicking from one position to the next as you rotate the rotor by hand with no power

applied.

When power is applied, it is directed to only one of the stator pairs of windings, which

will cause that winding pair to become a magnet. One of the coils for the pair will become

the north pole, and the other will become the south pole. When this occurs, the stator coil

that is the north pole will attract the closest rotor tooth that has the opposite polarity, and

the stator coil that is the south pole will attract the closest rotor tooth that has the opposite

polarity. When current is flowing through these poles, the rotor will now have a much

stronger attraction to the stator winding, and the increased torque is called

holding torque.

By changing the current flow to the next stator winding, the magnetic field will be

changed 90. The rotor will only move 30 before its magnetic fields will again align with

the change in the stator field. The magnetic field in the stator is continually changed as the

rotor moves through the 12 steps to move a total of 360. Figure 2 shows the position of the

rotor changing as the current supplied to the stator changes.

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FIGURE 2 Movement of the stepper motor rotor as current is pulsed to the stator.

(a) Current is applied to the top and bottom windings, so the top winding is north, (b)

Current is applied to left and right windings, so the left winding is north, (c) Current

is applied to the top and bottom windings, so the bottom winding is north, (d) Current

is applied to the left and right windings so the right winding is north.

In Fig. 2a you can see that when current is applied to the top and bottom stator

windings, they will become a magnet with the top part of the winding being the north pole,

and the bottom part of the winding being the south pole. You should notice that this will

cause the rotor to move a small amount so that one of its south poles is aligned with the

north stator pole (at the top), and the opposite end of the rotor pole, which is the north pole,

will align with the south pole of the stator (at the bottom). A line is placed on the south-

pole piece that is located at the 12 o'clock position in Fig. 2a so that you can follow its

movement as current is moved from one stator winding to the next. In Fig. 2b current has

been turned off to the top and bottom windings, and current is now applied to the stator

windings shown at the right and left sides of the motor. When this occurs, the stator

winding at the 3 o'clock position will have the polarity for the south pole of the stator

magnet, and the winding at the 9 o'clock position will have the north-pole polarity. In this

condition, the next rotor pole that will be able to align with the stator magnets is the next

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pole in the clockwise position to the previous pole. This means that the rotor will only need

to rotate 30 in the clockwise position for this set of poles to align itself so that it attracts

the stator poles.

In Fig. 2c you can see that the top and bottom stator windings are again energized, but

this time the top winding is the south pole of the magnetic field and the bottom winding is

the north pole. This change in magnetic field will cause the rotor to again move 30 in the

clockwise position until its poles will align with the top and bottom stator poles. You

should notice that the original rotor pole that was at the 12 o'clock position when the motor

first started has now moved three steps in the clockwise position.

In Fig. 2d you can see that the two side stator windings are again energized, but this

time the winding at the 3 o'clock position is the north pole. This change in polarity will

cause the rotor to move another 30 in the clockwise direction. You should notice that the

rotor has moved four steps of 30 each, which means the rotor has moved a total of 120

from its original position. This can be verified by the position of the rotor pole that has the

line on it, which is now pointing at the stator winding that is located in the 3 o'clock

position.

Types of Stepper Motors:

Stepper Motors come in a variety of sizes, and strengths, from tiny floppy disk motors,

to huge machinery steppers rated over 1000 oz in. Three basic types of stepper motors

include the permanent magnet motor, the variable re-luctance motor, and the hybrid

motor, which is a combination of the previous two.

Stepping Modes

The following are the most common drive modes.

Wave Drive (1 phase on)

Full Step Drive (2 phases on)

Half Step Drive (1 & 2 phases on)

Microstepping (Continuously varying motor currents)

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For the following discussions please refer to

the figure 9.

In Wave Drive only one winding is energized

at any given time. The stator is energized

according to the sequence A -> B -> A -> B

and the rotor steps from position 8 -> 2 ->4 ->

6. For unipolar and bipolar wound motors with

the same winding parameters this excitation

mode would result in the same mechanical

position. The disadvantage of this drive mode

is that in the unipolar wound motor you are only

using 25% and in the bipolar motor only 50%

of the total motor winding at any given time. This means that you are not getting the

maximum torque output from the motor.

In Full Step Drive you are energizing two phases at any given time. The stator is

energized according to the sequence and the rotor steps from

position 1 ->3 ->5-> 7 . Full step mode results in the same angular movement as 1 phase on

drive but the mechanical position is offset by one half of a full step. The torque output of

the unipolar wound motor is lower than the bipolar motor (for

motors with the same winding parameters) since the unipolar motor

uses only 50% of the available winding while the bipolar motor uses

the entire winding.

Half Step Drive combines both wave and full step (1&2 phases on) drive modes. Every

second step only one phase is energized and during the other

steps one phase on each stator. The stator is energized according to the sequence

and the rotor steps from position 1 ->2 -> 3-> 4 ->5 -> 6

-> 7 -> 8. This results in angular movements that are half of those in 1- or 2-phases-on

drive modes. Half stepping can reduce a phenomena referred to as resonance which can be

experienced in 1- or 2- phases-on drive modes.

The excitation sequences for the above drive modes are summarized in Table 1.

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re 9 Unipolar and bipolar wound

per motors.


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In Microstepping Drive the currents in the windings are continuously varying to be able

to break up one full step into many smaller discrete steps.

Shortcut for finding the proper wiring sequence

For 5 wires 1 is common to be plugged at positive supply and rest four to the pulses.

For 6 wires 2 are common to be plugged at positive supply and rest four to the pulses.

Connect the center tap(s) to the power source (or current-Limiting resistor.) Connect

the remaining 4 wires in any pattern. If it doesn't work, you only need try these 2 swaps...

1 2 3 4 - (arbitrary first wiring order)

1 2 4 3 - switch end pair

1 4 2 3 - switch middle pair

You're finished when the motor turns smoothly in either direction. If the motor turns in

the opposite direction from desired, reverse the wires so that ABCD would become DCBA.

Wiring of stepper motor of different number of wires:

4 wires 5 wires 6 wires 8 wires

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Now that we are done with the circuitry for the wiring sequence, and theory of stepper

motor, we will build up a circuit through the use of TTL device to get a supply voltage of

12V.this is because, our stepper motor used is a 12V one and the parallel port gives us only

5V. But before that lets discuss how to intract with parallel port.

2. SOME BASICS OF A PARALLEL PORT

What is a port?

A port contains a set of signal lines that the CPU sends or receives data with other

components. We use ports to communicate via modem, printer, keyboard, mouse etc. In

signaling, open signals are "1" and close signals are "0" so it is like binary system. A

parallel port sends 8 bits and receives 5 bits at a time. The serial port RS-232 sends only 1

bit at a time but it is multidirectional so it can send 1 bit and receive 1 bit at a time...

Figure 10. Parallel Port Configuration

Parallel Port - Data Ports:

In sending the sequences, you will need the data ports which can be seen in the picture

from D0 to D7 .

Parallel Port - Status Ports:

These ports are made for reading signals. The range is like in data ports which are S0-

S7. But S0, S1, S2 are invisible in the connector. And S0 is different; this bit is for timeout

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flag in EPP (Enhanced Parallel Port) compatible ports. The address of this status port is

0x379 . This will always be refer to "DATA+1" and it can send 5 numeric data from the 10

- 11 - 12 - 13 - 15 th pins. So how can we reach the data ports? It is simple: every parallel

port has an address. In Windows 2000, you can see yours by Settings > Control Panel >

System > Hardware > Device Manager > Ports (COM & LPT) > Printer Port(LPT1) >

Properties = in Resources > Resource Setting and you can see your address for your

parallel port. For Ex: Generally it is 0378-037F. This is hexadecimal like in math (mod 16).

0x378 belongs to 888 in decimal form. In this way you can look for your com port or game

port addresses. Let's enlighten these bits with a printer example:

S0: This bit becomes higher (1) if a timeout operation occurs in EPP mode.

S1: Not used (Maybe for decoration :))

S2: Mostly not used but sometime this bit shows the cut condition (PIRQ) of the

port

S3: If the printer determines an error it becomes lower (0). Which is called nError

or nFault

S4: It is high (1) when the data inputs are active. Which is called Select

S5: It is high(1) when there is no paper in printer. Which is called PaperEnd,

PaperEmpty or PError

S6: It sends low impact signaling when the printer gets a one byte data. Which is

called nAck or nAcknowledge

S7: This is the only reversed pin on the connector (see my table in the article) . If

the printer is busy and it cannot get any additional data this pin becomes lower.

Which is called Busy

Parallel Port - Control Ports:

This port usually used for outputting but these can be used for inputting. The range is

like in data ports C0-C7 but C4, C5, C6, C7 are invisible in connector. And the address for

this is 0x37A

C0: This pin is reversed. It sends a command to read D0-D7 on the port. When the

computer starts it is high in the connector. Which is called nStrobe

C1: This pin is reversed. It sends a command to the printer to feed the next line. It is

high in the connector after the machine starts. Which is called Auto LF

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C2: This pin is for reset the printer and clear the buffer. Which is called nInit,

nInitialize

C3: This pin is reversed. Sends a high(1) for opening data inputs. It is low after the

machine starts. Which is called nSelectIn

C4: Opens the cut operation for the printer. Not visible in the connector...

C5: Sets the direction control in multidirectional ports. Not visible in the

connector...

C6: Not used and also Not visible in the connector...

C7: Mostly not used but it is used as a C5 in some ports. Not visible in the

connector...

Parallel Port -Ground Pins:

These are (G0 - G7) the pins from 18 to 25 . These are mostly used for completing the

circuit. Different pins are required when using all the pins including the inputs.

After these we will be using data ports in experiment because there are reversed pins in

control and status ports. Here is an explanation for reversed pins: While you are not

sending any signals to the data port it is in closed position like "00000000" so the 8 pins

have no voltage on it (0 Volt) .If you send decimal "255" (binary "11111111") every pin

(D0-D7) has a +5 Volt... On the other hand, if we use control ports, there are reversed pins

which are C0, C1 and C3 so while we send nothing to the control port its behaviour is

"0100" in binary (decimal "11")...

Signal BIT PIN Direction

-Strobe C0 1 Output

+Data Bit 0 D0 2 Output


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-Acknowledge S6 10 Input

+Busy S7 11 Input

+Paper End S5 12 Input

+Select In S4 13 Input

-Auto Feed C1 14 Output

-Error S3 15 Input

-Initialize C2 16 Output

-Select C3 17 Output

Ground -18-

25Ground

CIRCUIT

Electricity - Lets get some Zzzzzttt zzzzttt...

Note- Here the circuit is based on running a stepper motor of 12V (dc), 1.8

DEG/Step, .16A/Phase

Here, we will build up a circuit through the use of TTL device to get a supply voltage

of 12V; this is because, our stepper motor used is a 12V one and the parallel port gives us

only 5V.

Here I have used IC ULN2803, which is an 8-bit, TTL-input npn Darlington driver

with a maximum rating of 50V, 500mA. You can also use high current gain transistor like

CMJE 3055T and place diodes to block the back current flow.

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As Parallel port is very delicate port attached with mother board, any back current or

reverse emf can blow your entire parallel port along with motherboard off. To prevent this

you need to isolate it through optocouplers. Any optocouplers will serve the purpose and

safeguard the computer. Here I have used IC 4N35.

Figure 10. 4N35 IC configuration

Figure 11. IC ULN2803 configuration

The Circuit Diagram:

The simplest circuit diagram with no optocouplers is the figure 12:

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Figure 12. Circuit diagram 1

Enhancing the circuit.

You can add optocouplers for safety of your motherboard. As nobody wants to blow

the motherboard through reverse emf sent back or if IC internals get short circuited.

All you need to do is connect the dataport inputs to Anode of IC 4N35 or any

optocouplers. Make cathode ground by grounding to any of the ports ground pin.

On the other side, connect the emiiter to to IC and give 5V to the collector.

This will act as a switch between your circuit and parallel port safeguarding it from any

damage.

And

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If you want to build the circuit without an IC

C MJE 3055T

What if you want to make your own Darlington pair. Well ofcource you can.

Here I show the circuit using very high current gain robust npn transistor Mje 3055T.

MmmI tried to make it on paint, but my mice drawing being very poor I will explain

it

Connect the optocpupler input from parallel port as described above.

Now, you dont need additional 5 V supply as you can take 12 V from the other

circuit by making these simple changes:

o Connect the emitter of optocoupler to base of transistor.

o Connect the collector of optocoupler to the collector of the transistor.

What this will do is act as a switch. As soon as the photo-diode is activated

it infrared light, which falls on the base of optocoupler, making it saturate. It

will hence pass current from collector to emitter. This will trigger base of

3055T transistor to go into saturation.

Ground the emitter of 3055T transistor to ground of 12V supply.

Put diodes IN4007 in reverse bias direction from negative and positive supply

of 12 V with the collector. That is, positive end in the negative supply and the

other to collector. And the negative side of diode to positive supply of 12V and

other end to collector just to make sure that any back current doesnt flow.

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If you want, put a good capacitor (which can sustain) between negative and

positive supply of 12V as a filter in the circuit. I have used 100 Micro F, 63V

electrolytic capacitor.

Now all set and done in securing and enhancing the circuit Now connect the

common cord of stepper motor to positive supply and rest four into the collector

of the transistors.

The Programming part

Before Coding

Mmmm A problem that plagues Windows NT/2000 and Windows XP

Unlike Windows 95 & 98, Windows NT/2000/XP will cause an exception (Privileged

Instruction) if an attempt is made to access a port that you are not privileged to talk too.

Actually it's not Windows NT that does this, but any 386 or higher processor running in

protected mode.

Accessing I/O Ports in protected mode is governed by two events, The I/O privilege

level (IOPL) in the EFLAGS register and the I/O permission bit map of a Task State

Segment (TSS).

Under Windows NT, there are only two I/O privilege levels used, level 0 & level 3.

Usermode programs will run in privilege level 3, while device drivers and the kernel will

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run in privilege level 0, commonly referred to as ring 0. This allows the trusted operating

system and drivers running in kernel mode to access the ports, while preventing less trusted

usermode processes from touching the I/O ports and causing conflicts. All usermode

programs should talk to a device driver which arbitrates access.

The I/O permission bitmap can be used to allow programs not privileged enough (I.e.

usermode programs) the ability to access the I/O ports. When an I/O instruction is

executed, the processor will first check if the task is privileged enough to access the ports.

Should this be the case, the I/O instruction will be executed. However if the task is not

allowed to do I/O, the processor will then check the I/O permission bitmap.

The I/O permission bitmap, as the name suggests uses a single bit to represent each I/O

address. If the bit corresponding to a port is set, then the instruction will generate an

exception however if the bit is clear then the I/O operation will proceed. This gives a

means to allow certain processes to access certain ports. There is one I/O permission

bitmap per task.

Accessing I/O Ports under NT/2000/XP

There are two solutions to solving the problem of I/O access under Windows NT. The

first solution is to write a device driver which runs in ring 0 (I/O privilege level 0) to access

your I/O ports on your behalf. Data can be passed to and from your usermode program to

the device driver via IOCTL calls. The driver can then execute your I/O instructions. The

problem with this, is that it assumes you have the source code to make such a change.

Another possible alternative is to modify the I/O permission bitmap to allow a

particular task, access to certain I/O ports. This grants your usermode program running in

ring 3 to do unrestricted I/O operations on selected ports, per the I/O permission bitmap.

This method is not really recommended, but provides a means of allowing existing

applications to run under windows NT/2000. Writing a device driver to support your

hardware is the preferred method. The device driver should check for any contentions

before accessing the port.

Well, there are lots of routines, source codes, device drivers, dlls available on the

internet who will make your task easy. Like userport1, porttalk, give-io, remove-give-io,

inpout32, etc etc.

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You can run userport1 routine and get freed, or if you need dlls get ipout32.dll(latest

version) and use it.

Now Lets make the code to do the rest

I used inpout32.dll in my application as the Sir (Ram Kishore) who thought me about

this knows Visual Basic very well, so I learned VB and worked with him. You can check

the workflow below for inpout32.dll and also you can get the source of the dll from the

internet.

Note: I am importing it with the reference of http://www.logix4u.net/ So for further

info about the driver check out the site...

The Program

I made the coding in Microsoft Excel VB editor as in excel, it complies automatically

and you can make dynamic changes. It doesnt create the exe file, but excel worksheet act

as a form.

In Excel go to tool->Macros->VB editor.

In new window, click insert Module.

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In module type:

Public Declare Function Inp Lib "inpout32.dll" Alias "Inp32" _

(ByVal PortAddress As Integer) _

As Integer

Public Declare Sub Out Lib "inpout32.dll" Alias "Out32" _

(ByVal PortAddress As Integer, _

ByVal Value As Integer)

This will call ipout32.dll from system32 directory of your windows, and your port will

also open.

Now create buttons in worksheet

In editor,

Edit buttons as follows

Private Sub

CommandButton1_Click()

countit = 0

myTimer = 0

countit = Sheet1.Cells(4, 1)

MsgBox "Before Starting...Please be

Patience as it may take few minutes"

Do While countit > 0

myTimer = Sheet1.Cells(4, 3)

Out 888, 3

Do While myTimer > 0

myTimer = myTimer - 1

Loop


Out 888, 6



Loop

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Out 888, 12




Loop

Out 888, 9




Loop

countit = countit - 1

Loop

Out 888, 0

MsgBox "Done"

End Sub

Private Sub


Out 888, 0

End Sub

Private Sub


countit = 0

myTimer = 0






Out 888, 1



Loop


Out 888, 2



Loop

Out 888, 4




Loop

Out 888, 8




Loop


Loop

Out 888, 0

End Sub

Private Sub


countit = 0

myTimer = 0




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Out 888, 1



Loop


Out 888, 3



Loop

Out 888, 2




Loop

Out 888, 6




Loop


Out 888, 4



Loop


Out 888, 12



Loop

Out 888, 8




Loop

Out 888, 9




Loop


Loop

Out 888, 0

End Sub

Private Sub


countit = 0

myTimer = 0






Out 888, 8



Loop


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Out 888, 4



Loop

Out 888, 2




Loop

Out 888, 1




Loop


Loop

Out 888, 0

End Sub

Private Sub


countit = 0

myTimer = 0






Out 888, 9



Loop


Out 888, 12



Loop

Out 888, 6




Loop

Out 888, 3




Loop


Loop

Out 888, 0

MsgBox "Done"

End Sub

Private Sub


countit = 0

myTimer = 0






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Out 888, 9



Loop


Out 888, 8



Loop

Out 888, 12




Loop

Out 888, 4




Loop


Out 888, 6



Loop


Out 888, 2



Loop

Out 888, 3




Loop

Out 888, 1




Loop


Loop

Out 888, 0

End Sub

Also I/O Port Access in Turbo C,

Borland C/C++

Turbo C and Borland C/C++ provide

access to the I/O ports on the 80x86 CPU

via the predefined functions

inportb / inport and outportb / outport.

int inportb(int portid); /* returns a byte

read from the I/O portportid*/

int inport(int portid); /* returns a word

read from the I/O portportid*/

void outportb(int portid, unsigned char

value);

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/* writes the byte value to

the I/O portportid*/

void outport(intportid, int value);

/* writes the word value

to the I/O portportid*/

#include

#include

#define Data 0x378

#define Status 0x379

#define Control 0x37a

unsigned char Bits;

outportb(Data,Bits); /* output data */

Bits = inportb(Status); /* input data */

I got a program for same to run in

UNIX. I have not checked it, neither I

had made. But it has been tested and

run. I got it from, Mr. Rachit Rastogi

doing final year M.Tech in IS from

IIITA. Heres the code

#include

#include

#include

#include

#include

#include

// global data required for terminal

settings and char value

static struct termios

initial_settings,new_settings;

static char key;

static int stepData[4]={1,2,4,8};

static int pos=1;

static int peek_char=-1;

// global data declaring port values

#define DATAPORT 0x378

#define CONTROLPORT 0x37a

//functions declarations

void init_kb();

void close_kb();

void move_right();

void move_left();

void move_forward();

void move_backward();

void stop();

enum mot {still,forward,backward};

static enum mot motVal=still;

int kbhit();

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int readch();

int main(void)

{

int x,temp,id,uid;

// uid=getuid();

init_kb(); //initialize keyboard

if(ioperm(DATAPORT,3,1)!=0) // if

permissions failed

{

printf("premission to the ports

denied");

close_kb();

return 0;

}

printf("permission to the port

granted\n");

outb(0,CONTROLPORT); //set the

mode of the parallel port to write mode

//setuid(uid);

printf("port mode successfully

changed to write mode\n\n");

outb(0,DATAPORT);

printf("motor intialized\n ");

printf("entering the motor control

area\n");

while(1)

{

key=kbhit();

if(key=='q')

break;

if(key=='6')

move_right();

if(key=='4')

move_left();

if(key=='8')

move_forward();

if(key=='2')

move_backward();

if(key=='5')

stop();

}

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outb(0,DATAPORT);

close_kb();

exit(0);

}

// function definitions

void stop()

{

motVal=still;

outb(0,DATAPORT);

}

void move_right()

{

if(motVal==forward)

outb(9,DATAPORT);

if(motVal==backward)

outb(10,DATAPORT);

if(motVal==still)

outb(8,DATAPORT);

//outb(stepData[pos+

+],DATAPORT);

//pos=pos%4;

}

void move_left()

{

if(motVal==forward)

outb(5,DATAPORT);

if(motVal==backward)

outb(6,DATAPORT);

if(motVal==still)

outb(4,DATAPORT);

//outb(stepData[pos--],DATAPORT);

//pos=(pos+4)%4;

}

void move_forward()

{

motVal=forward;

outb(1,DATAPORT);

}

void move_backward()

{

motVal=backward;

outb(2,DATAPORT);

}

void init_kb()

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{

tcgetattr(0,&initial_settings);

new_settings=initial_settings;

new_settings.c_lflag &= ~ICANON;

new_settings.c_lflag &= ~ECHO;

new_settings.c_lflag &= ~ISIG;

new_settings.c_cc[VMIN] = 1;

new_settings.c_cc[VTIME] = 0;

tcsetattr(0,TCSANOW,&new_setting

s);

}

void close_kb()

{

tcsetattr(0,TCSANOW,&initial_setti

ngs);

}

int kbhit()

{

char ch;

int nread;

if(peek_char !=-1)

return 1;

new_settings.c_cc[VMIN] = 0;


s);

nread=read(0,&ch,1);

new_settings.c_cc[VMIN]=1;


s);

if(nread ==1)

{

peek_char=-1;

return ch;

}

return 0;

}

int readch()

{

char ch;

if(peek_char !=-1)

{

ch=peek_char;

peek_char=-1;

return ch;

}

read(0,&ch,1);

return ch;

}

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documentation stepper motor

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