Help with parallel port programming

[stanzlavos]

My motherboard is Asus M3A78-EM. It doesnt have a parallel port connection. However, it does have 25 pins on it marked LPT and it is said that with an adapter, it can be used as a normal parallel port.

I used to program my 89sXX microcontroller with the ISP flash porgrammer by Asim. Actually i had taken the connection on a bread board itself and worked fine.

Now I made an adapter which connects directly to the motherboard. And i took connections only from the required pins as described in the circuit diagram that i was following. Now when i place a microcontroller, and try to retrieve its signature, it shows different values and once in a while it shows the correct device signature. But then again, when i try to burn, it tells that the signature didnt match.

This same setup was used earlier to program. And i am certain that i have taken the correct connections from the motherboard. (And it does retrieve the correct signature sometimes.). What could be the problem ?

Please help..

 

[welove8051]

hi, what is the programmer circuit you are using. if you want you can compare with my post in www.free8051projects.blogspot.com.

regards
kj

 

[stanzlavos]

The circuit I am using is this :

**broken link removed**

I am not using the parallel port pin 5 connection. Instead pins 40 and 31 are connected directly to Vcc. I know that this will work because I have been using this circuit on a bread board for a year from a normal parallel port (on my old motherbaord).

And I did forget to mention something. I had accidently interchanged the GND and LPT pin 9 connection. Could this have damaged the port ??

 

[eldhose555]

And I did forget to mention something. I had accidently interchanged the GND and LPT pin 9 connection. Could this have damaged the port ??[/quote]


pls read this topic to test your port
https://www.epanorama.net/circuits/parallel_output.html

 

[QAZI IMRAN]

hi
i am the beginner student want to learn how to promgrame the controller 89c51 or 8251. please help me to do it. please i will be very thankful to you for it.