Using Java for parallel port access

[r_pem]

hello, please could someone help me out
right the task is as follows:
design a system to measure the mains frequency as accurately as possible and then display this on a web accessible computer,
now the thing is i know i want to use a parallel port to connect the device to the computer however i am a little confused as to how i am going to read in the values and then display them onto the computer. we have decided to use java, i would be really grateful if you could pass on any relevant examples, tutorial or solutions on how to go about tackling the task!!!

thx

 

[FoxyRick]

phototransistor connected to parallel port

You're not the first person to ask questions like this here - is this a lab project by any chance?

Anyway, see this thread for Java libraries for parallel port access:



Check here for a parallel port doc:



And here for some basic parallel port interfacing:

**broken link removed**

Personally though I would use the serial port and an MCU. If you are trying not to use an MCU (just F-to-V convertor and ADC?) then the parallel port is the probably way to go.

FoxyRick.

 

[yogi]

measure frequency with parallel port

u connect a step down transformer to 230 v

we get output 12v

convert it to 5 v clock pulse using comparator

then connect it to d0

use pgm to check it

 

[IanP]

Re: Parallel port

Other option is to use an optocoupler.
The diode can be connected in series with 4.7µF(250Vac) capacitor and a reverse pollarity diode anti-parallel.
The output transistor will be connected between GND (E) and any of datalines of the prallel PC port (with 4k7-10k pull-up resistor) (C).
Having this square wave you can write an application (in any language, starting from old assemble or basic, VB, C, .... ++) which counts time of inputs H or L and converts it to the mains frequency..

 

[hassana]

Re: Parallel port

I am looking for a book for interfecing parallel port with microcontrollers what is the best bookk?

 

[Nick C.]

Re: Parallel port

I am looking for a book for interfecing parallel port with microcontrollers what is the best bookk?

Parallel Port Complete

**broken link removed**

 

[artem]

Parallel port

If your AC line is up 100 % you can make power free conversion like :

use serial ADC instead of parallel , it can be connected to rs232 instead of parallel port .
Supply adc directly from 220V and use ioptocoupler for rs 232 connection . You have to play with rs232 lines to get opto output into 232 voltage range as :
- set one of the 232 control lines to 0 adnother to 1.
- using transistor optocoupler simple put resistor on one of the phototransistor output . The point of connection will be your output data to rs232 input . Remnant unconnected transistor and resistor sides will be connected to above mentioned rs232 control lines according to phototransistor polarity .

 

[ro_begum]

Re: Parallel port

Hi, Im doing the same project (measuring mains frequency) but we were thinking of using JavaScript and CGI with HTML. Can you please please help me out on how I can start my pogram because I'm really baffled. Any info would be great, thanx.