Chapter 9 SOFTWARE

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Chapter 9SOFTWARE HARDWARE INTERFACES
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Outline

• Introduction on software hardware interfaces
• Software programming language types
• Computer ports for communication
• Interface using C language

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Software Type

• Machine Language development software
• - Assembly, Pbasic, C
• - For firmware programming purposes
• High Level
• - C/C, Cobol, Fortron
• - HTML, XML, Php etc.
• Application Level
• - Visual Basic, LabVIEW, Multimedia
  Developer
• - Virtual system, interactive, user friendly
• - User interface

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Hardware

• Interface card system (I/O card)
• Application machines
• - ATM, Vending, petrol pump etc.
• Computer communication media
• - Coxial cable, Fibre optic, RF wave etc.
• Computer ports and protocol
• - Parallel port, serial port,
• Universal Serial Bus (USB) etc.
• Communication Protocol
• - RS232, RS422, RS485, TCP/IP etc.

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Basic Computer Communication ports

• Serial port
• - Using for RS232, RS422 and TCP/IP protocol
• - Commonly DB9 and DB25 pins
• Parallel port
• - Using printing purposes
• - Commonly DB25 pins
• Universal Serial Bus (USB)
• - Multi-purposes port
• - Commonly have several USB ports in one PC.
• - Suitable for high storage data. Eg
  MPEG,JPEG etc.

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Serial Ports Pin Configuration
DB9 pin
DB25 pin
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USB Ports Type
Type A Port
Type B Port
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Parallel Port
Pin Configuration
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Parallel Port DB25 Pin details
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How to program Parallel Port using C

• The calculation
• The value that send via program is binary number
• Data pins configuration and decimal value

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How to program Parallel Port using C

• Function in C
• porttalk need to be installed to set the
  "pt_ioctl.c
• library. Base address of data for LPT1 is 378
  (0x378)
• Basic function - OpenPortTalk (),
  outportb(0xBase,0xn), ClosePortTalk ()
• Formula
• 0xn
• which n b0b1b2.
• Example
• If Pin 2 and 3 want to be set as HIGH (Logic
  1). So, the n
• value that need to be stated in the
• LPT port function in C
• n 12 3

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Example program code in C
OpenPortTalk () outportb(base_addr,0x00) //Low
voltage (0-0.3VDC) to all Data ports
(D0-D7) ClosePortTalk () for(x0xlt10x) pr
intf("Output will be HIGH\n") OpenPortTalk
() outportb(base_addr,0x01)//High voltage
(5VDC) to port D0 only ClosePortTalk
() getch() return (0)
include ltstdio.hgt include ltwindows.hgt //call
os (windows)
include
"pt_ioctl.c // talking to device driver include
ltconio.hgt define base_addr 0x378 // initialize
parallel port address main() int k,
x for(k0klt10k) printf("Ouput will be
LOW\n")
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void main(void) outportb(0x378,0xFF)
Example C program for the motor
void main(void) outportb(0x378,0x01) //pin 2
high outportb(0x378,0x00) //switch off pin
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Example C program for the motor
includeltstdio.hgt includeltconio.hgt
includeltdos.hgt   main() outportb(0x378,0x00
) ---------STOP MOTOR sleep(2)
outportb(0x378,0x01)---------MOVE MOTOR(CCW)
sleep(2) outportb(0x378,0x02)---------MOVE
MOTOR(CW) sleep(2) outportb(0x378,0x03)-------
--MOVE MOTOR(Break!) sleep(2) return 0
eg sleep(2)-----delay or sleep for 2 seconds eg
delay(500) -------delay for 500
milliseconds
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References

• http//www.faqs.org/docs/Linux-HOWTO/Serial-Progr
  amming-HOWTO.html
• http//www.beyondlogic.org/spp/parallel.htm
• http//www.epanorama.net/circuits/parallel_output.
  html
• http//www.experts-exchange.com
  /Programming/Programming_Languages/C
• http//www.logix4u.net/parallelport1.htm
• http//www.geocities.com/gear996/sub/parallel.html