Augustas
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RPi Rc car not working ok

Sat May 03, 2014 1:30 pm

Hello, i bought http://www.ebay.com/itm/360838243129 this module, do all like in the video tutorial [Mod Removed link - video wrong] But my motors running slowly. Then i connect to motor static all is normal. But then connect to motor module, not good at all. Please help me, i google it a lot for solution. Ask me for details if need it.
Image

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Gert van Loo
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Re: RPi Rc car not working ok

Sat May 03, 2014 7:48 pm

I have just approved your post.
Ask me for details if need it.
I strongly suggest that you provide more details now,
like a diagram how you connected things up.
Also try to measure voltage at some points and post the results.

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joan
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Re: RPi Rc car not working ok

Sat May 03, 2014 8:31 pm

Switch it off.

Could you say say which gpios are connected to which pins on the motor driver board?

What power and ground connections have you made to the motor driver board?

A photo of a top view of the motor driver board would be useful.

BMS Doug
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Re: RPi Rc car not working ok

Sat May 03, 2014 8:52 pm

Augustas wrote:Hello, i bought http://www.ebay.com/itm/360838243129 this module, do all like in the video tutorial [Mod Removed link - video wrong] But my motors running slowly. Then i connect to motor static all is normal. But then connect to motor module, not good at all. Please help me, i google it a lot for solution. Ask me for details if need it.
Image
Stop immediately and disconnect everything!
that Video will kill your raspberry pi.

people here will help you to connect this up correctly but that video shows the wrong set of connections to the raspberry pi and has been responsible for killing someone else's pi.
Doug.
Building Management Systems Engineer.

Tarcas
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Re: RPi Rc car not working ok

Sat May 03, 2014 9:38 pm

BMS Doug wrote:
Augustas wrote:Hello, i bought http://www.ebay.com/itm/360838243129 this module, do all like in the video tutorial [Mod Removed link - video wrong] But my motors running slowly. Then i connect to motor static all is normal. But then connect to motor module, not good at all. Please help me, i google it a lot for solution. Ask me for details if need it.
Stop immediately and disconnect everything!
that Video will kill your raspberry pi.

people here will help you to connect this up correctly but that video shows the wrong set of connections to the raspberry pi and has been responsible for killing someone else's pi.
I can confirm this, and in your picture it appears (though it's hard to see) that you correctly followed the incorrect step in the video. To fix this:
Disconnect all four wires to the "Enable" pins. The four pins are actually two Enable pins and two +5v pins. Jumper them together unless you deliberately control them in your code. You really only need the IN pins (although some people do find it more convenient to do PWM on the Enable pins, and let the IN pins separately set direction, you can PWM the IN pins as an alternative, to save 2 GPIO pins for other purposes.)

Once you've done that, tell us about your motors and your power supply, and whether you're using PWM in your code. One or more of these is probably responsible for your slow speed.

hades1989
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Re: RPi Rc car not working ok

Mon May 05, 2014 5:57 pm

hi, u can refer to my post, i asked bout this earlier, hope it helps.
http://www.raspberrypi.org/forums/viewt ... 37&t=76448

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raspberrypiguy1
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Re: RPi Rc car not working ok

Mon May 05, 2014 7:18 pm

Hello!

I am the creator of the tutorial in question ( I think anyway, the link isn't working for me ) and I believe that there is some explaining needed on my part.

It is *extremely* unlikely that my tutorials will ever kill your Pi - do you want to know why? Because I test them all myself. On all of my 4 Raspberry Pis of varying denominations. With different SD cards. And not one of them had any problem with this video: they all worked perfectly and I have used the L298N with lots of robots in the past.

If you don't think that my verification is enough then please don't take it from myself. That video has been watched over 200,000 times and I have had countless emails from people thanking its simplicity and showing me pictures of their own robots etc.

A little while after creating and uploading this tutorial a couple of people bought the enable pins to my attention. They do not need to be connected to the Pi at all however I did not know this at the time. The use of the Pi's pins is *unnecessary* but NOT dangerous! As I have said before this tutorial has worked perfectly for 1000s of people and I think that it is highly unlikely that you are a special case.

I upload tutorials for the benefit of the community and I do not take kindly to hate directed at them.

I am more than happy to help you and you can reach me at: theraspberrypiguy@gmail.com

As for the comment about my video being responsible for killing someone's Raspberry Pi... It seems odd that they have had that issue. I fail to understand how it can work for 1000s and then destroy 1 person's Pi. Most likely that was because of their own error eg: fault in wiring, accidental short

I am very surprised by this and hurt that people did not bring this to me before publicly denouncing it

Trying to be as helpful as possible,

Matthew
The Raspberry Pi Guy
Matt, The Raspberry Pi Guy YouTube channel, author of Learn Robotics with Raspberry Pi, available now: http://mybook.to/raspirobots, Computer Science & Electronics Undergraduate at The University of Edinburgh

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joan
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Re: RPi Rc car not working ok

Mon May 05, 2014 7:33 pm

The tutorial shows gpios being connected to the enable jumper pins. All you need to do is measure the voltage on those pins to confirm they may be at an unsafe voltage.

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raspberrypiguy1
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Re: RPi Rc car not working ok

Mon May 05, 2014 8:06 pm

joan wrote:The tutorial shows gpios being connected to the enable jumper pins. All you need to do is measure the voltage on those pins to confirm they may be at an unsafe voltage.
I understand that. But how can 1000s of other people be completely unaffected?

If everyone experienced problems then I would stick my hands up and admit it as my fault. 1 person in 100,000s of viewers happens to blow up his Raspberry Pi? I think that it is most likely an issue on their end.

Matt
Matt, The Raspberry Pi Guy YouTube channel, author of Learn Robotics with Raspberry Pi, available now: http://mybook.to/raspirobots, Computer Science & Electronics Undergraduate at The University of Edinburgh

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joan
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Re: RPi Rc car not working ok

Mon May 05, 2014 8:37 pm

raspberrypiguy1 wrote:
joan wrote:The tutorial shows gpios being connected to the enable jumper pins. All you need to do is measure the voltage on those pins to confirm they may be at an unsafe voltage.
I understand that. But how can 1000s of other people be completely unaffected?

If everyone experienced problems then I would stick my hands up and admit it as my fault. 1 person in 100,000s of viewers happens to blow up his Raspberry Pi? I think that it is most likely an issue on their end.

Matt
There are at least two problems with the tutorial.

The most obvious is connecting gpios to 5V. I don't know how long a gpio will survive, it will depend on how much current flows.

The second is that your motor driver board arrived without jumpers (at least I remember you saying that at one point).

This means that it's safe to feed 5V into the motor driver board because the motor supply voltage is isolated from the logic supply voltage.

All the boards I've received have had jumpers in place. This means the motor supply is powering the logic supply. This means it's not safe to connect Pi 5V to the motor supply logic supply.

Both the above can damage the Pi. The recent incidents aren't isolated. They pop up every now and then.

BMS Doug
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Re: RPi Rc car not working ok

Mon May 05, 2014 8:58 pm

raspberrypiguy1 wrote:Hello!

I am the creator of the tutorial in question ( I think anyway, the link isn't working for me ) and I believe that there is some explaining needed on my part.

It is *extremely* unlikely that my tutorials will ever kill your Pi - do you want to know why? Because I test them all myself. On all of my 4 Raspberry Pis of varying denominations. With different SD cards. And not one of them had any problem with this video: they all worked perfectly and I have used the L298N with lots of robots in the past.

If you don't think that my verification is enough then please don't take it from myself. That video has been watched over 200,000 times and I have had countless emails from people thanking its simplicity and showing me pictures of their own robots etc.

A little while after creating and uploading this tutorial a couple of people bought the enable pins to my attention. They do not need to be connected to the Pi at all however I did not know this at the time. The use of the Pi's pins is *unnecessary* but NOT dangerous! As I have said before this tutorial has worked perfectly for 1000s of people and I think that it is highly unlikely that you are a special case.

I upload tutorials for the benefit of the community and I do not take kindly to hate directed at them.

I am more than happy to help you and you can reach me at: theraspberrypiguy@gmail.com

As for the comment about my video being responsible for killing someone's Raspberry Pi... It seems odd that they have had that issue. I fail to understand how it can work for 1000s and then destroy 1 person's Pi. Most likely that was because of their own error eg: fault in wiring, accidental short

I am very surprised by this and hurt that people did not bring this to me before publicly denouncing it

Trying to be as helpful as possible,

Matthew
The Raspberry Pi Guy
Hi Matthew,

looking closely at your video we can see that you do not connect the control jumper (marked in Pink in Joan's image below)
but instead have the 5v supply to the L298N from your Pi's 5v supply. (although it is shown as connected in the diagram at 12:46)
mdb-a.gif
mdb-a.gif (48.92 KiB) Viewed 3365 times

at 11:00 you connect the 5v to GPIO4, why doesn't this fry your Pi? I don't know, perhaps this is related to your 5v coming originally from the pi (and therefore at least partially current restricted) where the person who's pi exploded had his 5v supplied via the (pink) control jumper from a 12v source by the onboard buck regulator.

I'm not intending to hate on your video, just to protect other people from losing their pi's in the same way. please re-shoot the video without the (potentially fatal) error and I'll happily give it a thumbs up and a positive comment.

Please, Please, remove the current video and replace it with a better one.

Doug.
Doug.
Building Management Systems Engineer.

Duane Degn
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Re: RPi Rc car not working ok

Sat Jul 12, 2014 3:58 am

raspberrypiguy1 wrote:It is *extremely* unlikely that my tutorials will ever kill your Pi - do you want to know why? Because I test them all myself. On all of my 4 Raspberry Pis of varying denominations. With different SD cards. And not one of them had any problem with this video: they all worked perfectly and I have used the L298N with lots of robots in the past.
You are *extremely* lucky if connecting 5V without any current limiting resistor to a GPIO pin didn't destroy any of your 4 boards. You are also *extremely* wrong!

Have you measured the voltage on what your are calling the second ENA? It's 5V! Please measure it.

I've accidentally connected 5V to a 3.3V I/O pin many times without the 5V killing the board, this certainly doesn't mean doing so is safe. You've been lucky, others understandably have not been.

Do you really think connecting 5V to a GPIO pin is safe?

People are telling you your method is killing their boards and it is almost certainly you're video to blame.

Experienced engineers are telling you your video has a serious (potentially likely fatal) error yet you prefer to take the word of the noobs who like your video.

BTW this issue has also been brought up several times in the video comments and in this thread.

I just recently found this thread where yet again you were told of the problem. It's hard to believe you're still refusing to fix the "How to Fry Your Pi" video.

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raspberrypiguy1
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Re: RPi Rc car not working ok

Sat Jul 12, 2014 7:44 am

This issue has now been rectified... Please read here for the conversation! http://www.raspberrypi.org/forums/viewt ... 25#p576825

I apologise profusely for any aggravation that might have been caused,

Matt
The Raspberry Pi Guy
Matt, The Raspberry Pi Guy YouTube channel, author of Learn Robotics with Raspberry Pi, available now: http://mybook.to/raspirobots, Computer Science & Electronics Undergraduate at The University of Edinburgh

uberscubajim
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Re: RPi Rc car not working ok

Sat Jul 12, 2014 10:08 am

I'll post this in the other threads as well...

I've taken a long look at the (now private) video and there are a couple of errors in it. The first one is where The Raspberry Pi Guy states that the maximum output of a GPIO is 50mA when in fact it's 16mA with a total of them all of 60mA (if I recall correctly).

However, the key issue is with connecting the 5V as well as the real enable to the GPIO. As has been pointed out this is a mistake and a fairly serious one.

However, if you have a board with no jumpers on it then you could well assume that you need to to set both the pins labelled enable high to enable the output. After all: two output pins per side so two enables sort of makes sense doesn't it? It's a fairly easy mistake to make.

OK, we can talk a lot about testing and getting others to check but for a 14 year old it's an understandable mistake. And TRPG did indeed test it and it all worked for him on several different set ups. It's a much more logical thought that a few people had wired it up wrong.

Yet, we've all wired Pi stuff up wrong and been amazed it all worked afterwards. I've run workshops where I've been amazed that none of the Pies were fried.

Which got me thinking. Sure, putting 5V into a GPIO is wrong, it's bad and may kill your Pi. But it often doesn't. Maybe something else was happening.

I have an idea about that. I sat down and looked at photos of the various versions of the board and then read the datasheet for the chip and a horrible idea came to mind.

The chip itself is rated to have its logic side powered at up to 7V. In fact reading the data sheet the "5V" input can be anything from 4.5V to 7V so the 5V in on the board probably ought to be marked "4.5V to 7V". Similarly, the 12V input can be anything up to 50V! Provided you don't exceed 2A. So far, so good.

However, often people might want to power their motors of 4AA batteries: exactly like in the video. This is a reasonable choice. It would appear that some of the boards have a jumper that allows you to power the chip from other power input (the nominal 12V one).

In fact, if you're powering 6V motors from a Pi this makes a lot of sense. No need to connect the 5V and the inputs just work.

BUT, and this is the nightmare, if that jumper comes preinstalled then never mind feeding 5V into a GPIO input, you're feeding 6V into the Pi's 5V line! Someone even mentioned using a 9V battery! If you put 9V onto a Pi's 5V line you are going to kill it!

This, I strongly suspect, is why a few people had such disastrous results.

Thoughts anyone?

Jim.

Duane Degn
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Re: RPi Rc car not working ok

Sun Jul 13, 2014 9:00 pm

uberscubajim wrote:I'll post this in the other threads as well...
Before posting this in multiple threads, I think it would be a good idea to get your information correct.

I do think the issue of the 5V being a problem when connected to a GPIO pin should be posted to other threads.
uberscubajim wrote:BUT, and this is the nightmare, if that jumper comes preinstalled then never mind feeding 5V into a GPIO input, you're feeding 6V into the Pi's 5V line! Someone even mentioned using a 9V battery! If you put 9V onto a Pi's 5V line you are going to kill it!
I don't understand your concern. In all cases (barring malfunction), you'll be feeding 5V to the GPIO pin. With the voltage regulator jumper peinstalled, the 78M05 will regulate it to 5V. You can use this 5V to power other devices. No nightmare at all (from this concern).

This is pretty easy to check with a multimeter.

The likely reason Matt's Pi boards didn't get burned out is whatever source he was using for his 5V supply didn't have the current capacity to burn out the board (and he got lucky (though it would have saved many other boards if his had burned out)). Boards with the jumper installed may have had a higher chance of damage since the 78M05 can supply at least 100mA of current (IIRC). But in all cases supplying 5V to a GPIO is a really bad idea (as was repeatedly explained to Matt).

With the jumper in place you get 5V and the current the battery pack and 78M05 can supply. Without the jumper you get 5V and however much current the 5V source you connected to the board can supply. Either way bad things are likely to happen.
uberscubajim wrote: This, I strongly suspect, is why a few people had such disastrous results.
I think it's very clear why so many people were having disastrous results as I explained here and BSM Doug explained above.

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