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007roy
01-17-2011, 12:23 AM
I had previously ordered two pieces of hercules lite 36v 8 amps motor drivers from nexrobotics.I cant find them anymore on the site.I am giving below the list of input pins to the motor driver and the voltages i have given to the pins
INA - 5V(logic high)
INB - 0V(logic low)
ENA - 5V
ENB - 5V
PWM- 5V
GND - cnctd to gnd
CS - not connected
+ - 12V
-- - 0V

I have connected all the pins according to the provided datasheet and have checked the connections thoroughly.I have not yet connected any motor yet ever to the motor driver.But I am not getting the expected and desired outputs.
I should be getting 12V at the outputs but I am not getting any voltage at the outputs.The difference in voltage between A and B are 0V.This is the same problem I am facing with both the motor drivers.
When I switched the logic high and logic low i.e.
INA - 0V(logic low)
INB - 5V(logic high)

leaving all the other pins as given above on one of the motor driver i got a voltage difference between A and B as 3V and on the other motor driver I got a voltage difference of 6V between A and B.The direction LEDs were glowing only on of the motor drivers and only in the second case.
We are really working hard to participate in the upcoming ROBOCON and cannot proceed further until this problem is solved.
I have ruled the chances of burning up the motor driver because i have never ever connected a motor to them.The motor driver never got heated up ever and it never gave the right voltages at the output right from the beginning.We are planning to run mechtex motors on these motor drivers.So please help me.Let me know if the motor drivers are faulty or anything.
The company is saying that the gnd pins are not common but i have checked them thoroughly and all the gnd pins are shorted.

avinash_g
01-17-2011, 09:08 AM
In most modern designs CS pin is active low and must be pulled low to make device go to working mode when CS is pulled high it goes to power saving mode.

But a more accurate solution can be provided by the designer of the device. So why don't you ask the seller ???

Most of the people here don't have much free time to study nexrobotics (or any other vendor's) designs and provide free TechSupport for them!

If its covered by warranty then get it replaced.

vikas
01-17-2011, 07:31 PM
@007roy ... Contact nex , no one here can really help you.

For us to help you , we will need schematic of the hardware in use,if you can provide then maybe someone has the time.

007roy
01-17-2011, 10:10 PM
Thanks for the quick reply guys.I had already contacted the company and all that they could come up with is that the gnd pin is not common.Today on further testing of the motor controllers i noted the following things.
As i kept on increasing the VDD voltage, at all times the difference in voltage between the two motor terminals was half the VDD voltage.When the VDD=17.5V the difference in terminals at the motor output was also 17.6V.That means at this value it was giving the proper output.Now immediately after 17.6 V as you increase the voltage the out put voltage falls to zero.Even though the max permissible voltage is 36V rated it stops giving output at 17.6V.
I know I am being tough to deal with but the company is not helping me in any way.And these are all the information i could gather.So does this situation and behaviour suggest anything to you guys?Like what could be wrong with this?
Thank YOu.

endlasuresh
01-17-2011, 10:58 PM
Thanks for the quick reply guys.I had already contacted the company and all that they could come up with is that the gnd pin is not common.Today on further testing of the motor controllers i noted the following things.
As i kept on increasing the VDD voltage, at all times the difference in voltage between the two motor terminals was half the VDD voltage.When the VDD=17.5V the difference in terminals at the motor output was also 17.6V.That means at this value it was giving the proper output.Now immediately after 17.6 V as you increase the voltage the out put voltage falls to zero.Even though the max permissible voltage is 36V rated it stops giving output at 17.6V.
I know I am being tough to deal with but the company is not helping me in any way.And these are all the information i could gather.So does this situation and behaviour suggest anything to you guys?Like what could be wrong with this?
Thank YOu.
sorry to hear and your project
If the company is not going to help you atleast then they are worse.I had seen recently their site and forum that does not contain any posts.I cant understand why do this companies open forums without helpful information or even cant help on their products.

vikas
01-18-2011, 07:34 AM
The details you have provided cannot be used to help you , please provide a schematic.

Or go step by step debugging the circuit based on component characteristic. Trace the paths and see whats wrong where.

MohitM
01-18-2011, 09:29 AM
I suggest a poll or a review of online shops that sell robotics/electronics stuff. A frank and no-holds-barred write-ups on who to buy from and who to avoid - with actual user reports.

avinash_g
01-18-2011, 09:43 AM
Its your right and their duty to provide you with help!

use their forum to ask
http://www.nex-robotics.com/forum-33.html

Also I don't think they are going to give you the schematic.
Rs. 2.5K + for a motor driver is too much!

May be you should ask for money back.

Any Good Online seller has a return policy!



I suggest a poll or a review of online shops that sell robotics/electronics stuff. A frank and no-holds-barred write-ups on who to buy from and who to avoid - with actual user reports.


These kind of problem persists because Indian users do not share their experience properly on the Web. They should share their good and bad buying experience actively on their social networking page, blogs, twitter and other forums (like RI) etc. They should donate some time reviewing products. Linking good products and service from their blogs, home page etc. This will give good service provider better page rank and more reach thus more people would have the opportunity to getter better products.

Now a days some companies are importing whole lot of attractive things like GLCDs, TFTs, Cameras, Complex sensors,Wireless Communication , ARM11, Touch screen etc just to fill up their catalog with almost no support(code, example, tutorials etc) at all. Thus they are NOT at all of any use (except for experienced people).

Most of the above need a very strong programming skills along with in depth knowledge of Common technique already developed and used in other OS and system.

For example a TFT LCD may seem a simple thing to a novoice student. But to draw a simple line on screen he/she may be confused. But a experienced programmers know a well know algorithm known as Bresenham's line algorithm exists, so he/she does not spend time reinventing the wheel.

I am a blog owner with nearly 1,50,000 page views per month, so I am constantly in touch with most of the embedded developers in India and I know what kind of questions they ask. Most have bought such stuff and asking for help that can't be provided in One or two posts. Most requires a lot of time and research and sometimes requires reading thousand pages of literature (like books and datasheets). Since I am a 100% profit oriented guy, I straight away delete posts or questions related to other Sellers Product on my webpages.

In my opinion a store/company with less product but more support is preferred over a company with a lots of stuffs (mostly imported from Sparkfun), images taken from Sparkfun and no local support at all.

I encourage buyers to ask for help (whenever their is genuine reason) from the sellers. Also do that on their forum posting sufficient details (so that they can understand your problem) not on phone or email. As this would also help other (remember to give back to society).

Oh!

I just had a look at Nex forum their are 0 post is all forums!

allbits
01-18-2011, 10:50 AM
Well.

I have purchased from almost all (except 2 or 3)online shops in India, and every vendor have their plus and negative points. I do not think it is fair for do shop bashing here, as facts are most of the times distorted. Nex robotics site having no posts should not have been a point, because I think it is not relevant to the issue. And I agree with Mohit., reviews should be posted by people who buy.

It is fair for the OP to post a query about something someone else has sold. He does that, because, he assumes there will be someone who has used that board here. I guess, Instead of bashing the shops, people who have time can try to answer, or leave the topic unanswered.

As to the OP, it will be of great help if you can post the datasheet here. If possible, post a photograph of the top and bottom sides. If you can post the datasheet, many of us here can help.

007roy
01-26-2011, 03:46 PM
Ok.i think i know what is the mistake.I got two new motor drivers of 24v and 15A from the same site.I have attached the manual for the motor driver.When i connected the motor to it and gave the PWM1 pin PWM signal and the other PWM2 pin logic high it was working fine without heating up when the frequency was around 1.7KHz which was being given by a frequency generator.In the datasheet it was given that PWM operations were till 10Khz.But from my microcontroller i was getting a PWM frequency of around 11KHz and i thought that it would also do.So i connected it and then the motor driver goes kaput.When i checked all the components on the motor driver the resistor at the PWM pins got burnt and now there is no output from it.Can you please tell me why this happened as i dont want to be repeating this again.And also at the frequency generator i was giving a square wave output with amplitude 5V.What do i do with the OFFSET knob on the machine and also what should be the amplitude of the wave?
please help.thank you.

vikas
01-26-2011, 04:40 PM
I got two new motor drivers of 24v and 15A from the same site.You must be really loyal customer of nex to buy again even with no support and your so called past experience. Just reconfirms nex that no need to bother with customer requests. Did you not learn from last mistake ? .

Anyhow -

Post the schematic !!! without that whatever you say is of no use to anyone.

007roy
01-26-2011, 10:44 PM
Sir,
I have no other choice than to buy from them because we have these really power hungry motors which take a lot of current.Something around 7 amps of stall current and 2-3 amps when running.I dunno where else can you get such high current rating motor drivers in india atleast.The board is a surface mounted thing and i do not have the schematic.I will upload the close up pics of the motor driver.Will that help in any way sir?Because i am ordering 6 more pieces for my other robot which has omni wheels and I need to know what my mistake is so that i do not commit the same mistake again.

robosoftsystems
02-14-2011, 12:31 PM
try these drivers... i hope they help
Amp rating: 20A
http://www.robosoftsystems.co.in/roboshop/index.php/development-boards/high-current-motor-driver.html

vikas
02-14-2011, 04:33 PM
about the robosoft bridge ..

I will recommend avoid them as they too do not provide any schematics, and you might land up in the same mess.

Simply avoid vendors who do not provide schematics ... like i do.

rajdeep_iitm
08-11-2011, 11:35 AM
Hi Newbie, I also have a similar project and was looking through the Nex Robotics website. Do the Hercules motor drivers work as mentioned? What was your experience?

hansje brinker
06-08-2012, 02:22 AM
I am pretty certain the chip is smt VNH3SP30 or VNH2SP30.
It looks very pin compatible o me.
see also http://www.pololu.com/catalog/product/707 for more details and specifications