View Full Version : one query in Booksbybibin

05-15-2006, 04:27 AM
hi bibin, i went through ur book on "My experiences in parallel Port Interfacing" and found it awesome.But i have few queries:-

1.When we write in the C program:

then how do we know which data ports/control ports have the bit(0/1)?

2.while making the connections on the breadboard, say i have connected the connector to the breadboard, then the data/control wires are connected to the former, then if i want to check the voltage signal in data port(3),so i should connect the multimeter's +ive terminal to 3rd data port line but which terminal of breadboard should be connected to gnd. of multimeter?
ie. i want to ask how do u decide the gnd. terminal of breadboard?

3.what are relays for?

4.how should we use the SMPS of the comp. as the power source of our external ckt. ? otherwise what should we buy in order to provide a power source of upto 6V for running my steper motor and its driver ULN?

5. are adapters used for constant voltage source(1.5-12V,0.5A as u have mentioned in the book? when are they preferred over SMPS?

PLZ. Do reply soon bcoz we need it in our B.Tech project urgently.

05-15-2006, 04:37 AM
After telling u abt my queries, let me also tell u abt my actual motive:

i want to interface stepper motor to computer through the parallel port using the motor's driver ULN...here i want to control (write) my motors starting, stopping and running for some given time duration (depending upon my C++ program's user response). Accordingly, i need to find the degrees rotated by the motors shaft.

05-15-2006, 12:42 PM
1.First thing.. it is 0x378 and not 578.. once you do that then it is simple..

you have 8 data pins from pin 2 to pin 9 ;0x55 = 0101 0101 that means pin 2,4,6,8 are on.. to check you can connect LEDs to all pins..

2. As far as ground is concerned pins 18-25 are all to be shorted and grounded..i.e. if you have an external power supply, then make all grounds common on the breadboard as simple as that.. and then use that row(which you have chosen as ground ) to connect other external ICs, ULN in your case...

3. Relays are electromagnetic switches, you give them a specific control voltage and they switch on, hence completeing a circuit..(dont have the time or patience to explain the whole working, which year did you say you were in??)

4. Waise.. a power source..an adapter..if you have heard of it...otherwise using an SMPS is simple, just learn how to use a multimeter for finding out voltages at pins and you will know....

5. SMPS is used when both 5V and 12 V are required at once and current requirememnts are more than what a simple adapter can provide.. adapters are preferred when they can be found more easily as compared to an SMPS..

I did not answer any of these questions because they are good questions.. but I think it is about time I answered odd questions and start linking other people to these instead of asking them to search as I have found out that people ARE NOT READY to SEARCH...


05-15-2006, 02:14 PM
thanks a lot for the help, rao. but its not that i m wary of searching but these are doubts, i think which can be better solved by experienced people like u who have gone thru the same ordeal. thanks once again.

It was just a typing mistake that i had written 578 instead of 378.

05-16-2006, 07:40 PM
Hi Gaurav
The out port thing which you asked.. actually there is a simple funda which works.. to solve this type of problems.

Check the header file where you will find the prototype of the APIs..
if you look into dos.h in Turboc then you will get the answer..
also if you are using turbo c then there are a lot of help files.. and all the fuctions are explaine properly..

always google is not the answer.. you can get the answer if you look into some of the things you already have..

it is always a good idea about telling the function prototype when any API is dicussed... i think yogi can include this too.

and about relays and other simple components.. you should know about those things.. these are the building blocks of any electronic circuits.. the basic components.. you how it will be if you go through any book ?
chk out .. many books / urls are already posted by yogi.. bibin john.. search for electronics in this site and you will get it..

when I had started electronics things I had purchased a lot of registers because those were cheap and were looking colourfull.. never used those for 2 years till I went to std 7...


05-17-2006, 12:54 PM
ya rao had given the right answer

b4 asking doubts u just search on net then u will get good answer
my first book
MY EXPERIENCE IN AUTONOMOUS ROBOTICS have explanation for all these, go through it first

Bibin John