pic18 motor control

7/30/2019 pic18 motor control

1/16

77

PIC18MICROCONTROLLER

MotorControMohamadFauziZakaria

http://fkee.uthm.edu.my/mfauzi

PART12

3 January, 2011mfauzi


2/16

RELAY

3a. Electromechanical Relay

Has three components:

o Spring

contacts

Relay characteristics to be considered Types of contacts SPST, SPDT, DPDT

Voltage and current for energizing the coil

pull-in (minimum) current = pull in voltage/coil resistance


4



3/16


4/16

7

Also called optocoupler

Used to reduce the effect of voltage spike especially in coil windingsystem (e.g.: motors).

transmitter and receiver

is to revent the

electrical current surgefrom reachin the

system


PART28



5/16

9

PIC18 CCP and ECCP Modules CCP Registers

1. CCPxCON : to select the compare,capture, and PWM modes

2. CCPRxLa. 16-bit compare register

b. 16-bit capture register

PIC18 Usage of Timers3. CCPRxH

c. 8-bit duty cycle register

10


6/16

11

There are three registers involved:

.2. PR2 : Period

.

4. T2CON: Timer2 Control

.

6. TRIS: I/O Direction

12

2 factors in creating pulses in PWM: Period

Duty Cycle (DC)

s o en s a e n e percen ages orm


7/16

13

14


8/16

15

16

Uses the PR2 register to set the PWM period

When TMR2 is equal to PR2, the following three events occur on the

next increment cycle:

TMR2 is cleared

The CCPx pin is set

exception: if PWM duty cycle = 0%, the CCPx pin will not be set

The PWM duty cycle is latched from CCPRxL into CCPRxH


9/16

17

uty yc e

Uses 10-bit register of Duty Cycle

DC9 DC8 DC7 DC6 DC5 DC4 DC3 DC2 DC1 DC0

CCPRxL CCPxCON

Decimal PointMain Duty Cycle

DC1 DC0 Value

0 0 0

0 1 0.25

1 0 0.5

1 1 0.75

18

1. Set the PWM period by writing to the PR2 register.

2. e e u y cyc e y wr ng o x or e g er s.

3. Set the CCPx pin as an output.

4. Using the T2CON register, set the prescale value.

5. Clear the TMR2 register content.

.

the decimal portion of the duty cycle.

7. ar mer .


10/16

19

Create a 2.5 kHzPWM with a 75%

DC on the CCP1 pinby using 4 prescaleand Fosc = 10 MHz.

PR2 = [Fosc/(Fpwm x 4 x TMR2 Prescale Value)] - 1

.

20

SpeedMotorControlthroughPWMgeneratingby

OnOff

at

any

pin

using

hardware

Timer

or

Software

Delay.

FeedbackSensor:

Encoder

CounterforT0CKIandT1CKI Polling/Interrupt.

INT0 1 2 ollin interru t.

OtherPins polling.

ADC


11/16

21

HBridgeMotorDriver

22


12/16

23

D BServomotor

24

Allservoshavethreewires:Black orBrown isforground.

Red isforpower(~4.86V).

Yellow,

Orange,

or

White is

the

signal wire

(3

5V).



13/16

PART325


26

3 common types that identified by the number of connections to the

.

Motor speed : measured in steps/s, is a function of the switching

. Holding torque: the amount of torque at zero rpm condition



14/16

27

Step angle: minimum degree of rotation associated with a single step.

ep per secon an rpm re a on


STEPPER MOTORstep sequence

28

Fullste HalfSte 8 Windin

(4step) step)

Normal

drive Wave

drive Normal A B C D

1 1 1 0 0 1

1 2 1 0 0 0 CCW

2 3 1 1 0 0

2 4 0 1 0 0

3 5 0 1 1 0

3 6 0 0 1 0

CW

4 7 0 0 1 1

4 8 0 0 0 1



15/16

STEPPER MOTOR INTERFACE

29using ULN2003



30



16/16


31


32

pic18 motor control

Documents