Parallel Port | Electronic Project Circuits

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Serial To Parallel Converter using MAX232

This converter may help if just the serial port on a personal computer is free, whereas the printer needs a parallel (Centronics) port. It converts a serial 2400 baud signal into a parallel signal. The TxD line, pin 3, CTS line, pin 8 and the DSR line, pin 6, of the serial port are used – see diagram. The CTS and DSR signals enable handshaking to be implemented. Since the computer needs real RS232 levels, an adaptation from TTL to RS232 is provided in the converter by a MAX232. This is an integrated level converter that transforms the single +5V supply into a symmetrical ±12V one.
The serial-to-parallel conversion is effected by IC1. This is essentially a programmed PIC controller that produces a Centronics compatible signal from a 2400 baud serial signal (eight data bits, no parity, one stop bit). The IC also generates the requisite control signals. If there is a delay on the Centronics port, the RS232 bitstream from the computer may be stopped via the Flow signal (pin 17). This ensures that no data is lost. The controller needs a 4 MHz ceramic resonator, X1.
Source: http://www.extremecircuits.net/2010/08/serial-to-parallel-converter.html

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Categories: Converter Circuit Tags: parallel port, serial port interface, Serial To Parallel Converter

ULN2003 Control Stepper Motor by Parallel Port

This is an easy to build stepper motor driver that will allow you to precisely control a unipolar stepper motor through your computer’s parallel port. With a stepper motor you can build a lot of interesting gadgets such as robots, elevator, PCB drilling mill, camera panning system, automatic fish feeder, etc. If you have never worked with stepper motors before you will surely have a lot of fun with this project.

Source:http://www.electronics-diy.com/stepper_motors.php

But This Stepper Motor Controller Connection Diagrams use 2 port voltage are 5Volt and 12V and four resistors , a zener diode.
The Four-Wire Connection the ULN2003 (High-Voltage High-Current Darlington Transistor Array
)/ MC1413 is a 7-bit 50V 500mA TTL-input NPN Darlington driver. This is more than adequate to control a four phase unipolar stepper motor such as the KP4M4-001.

Source: http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/