Arduino mega pwm issue

So I'm new to my robot lab but I've been tinkering around with it for a while. I've noticed that after I updated my MRL version that my arduino doesn't respond to changes in the arduino service when I try to set the outputs for any of the pwm pins. It seems that the service isn't even telling the arduino to output through these pins because the rx indicator light doesn't blink when I update the values. I'm not sure if this is just a case of my version or if its no worky. Any insight would be greatly appreciated 

GroG's picture

Hello and Welcome

Hello and Welcome Robotman,

My guess without looking at things, is you have a recent version or MRL(myrobotlab) and an old version of the Arduino MRLComm.ino sketch on the Arduino.  The protocol recently switched to support variable length messages.

If this is the problem, you should be able to download the latest MRL - unzip it, installl the Arduino service, load the new MRLComm.ino on the Arduino .. and you should be back in business !

If not hit the panic button and send us a NO-WORKY - details are here ->

Good Luck !

beetlejuice's picture

Perhaps, you just made an

Perhaps, you just made an error ..

Did you select the good arduino board, and the right com port ?

MRL Arduino service connect well to your arduino board ( yellow icon )?

GroG's picture

Ah...   I just thought of

I just thought of another thing that could go wrong..  Regrettably, the RXTX Library which MRL depends on to do serial communication will sometimes "hang"..

You mentioned that you were not even seeing the lights blink..  If RXTX is hung in a zombie process - no one else would be able to use the port.

Solution : (kill all Java!) - go to the Task Manager (Windows) or  (Linux) ps aux|grep java - and you can see other instances of Java - if they are zombies kill them all..

Windows - pluck them one by one in the task manger - right click -> kill

Linux - killall java

Roboman's picture

still no luck

Thanks for the help guys, I checked Everything you said, I reinstalled the arduino service and MRL but it now just returns Rx errors very very quickly whenever I try to activate a pwm pin on my arduino mega 2560. It usually records around 15,000 Rx errors every few seconds

GroG's picture

can you send a "no-worky" so

can you send a "no-worky" so I can see the log?

Roboman's picture


Already did


GroG's picture

Hmmm... I didn't get it  I

Hmmm... I didn't get it 

I did get a truncated file, but it wasn't in your directory ...

The file read :

Content-Disposition: form-data; name="user"
Content-Type: text/plain; charset=ISO-8859-1




Roboman's picture

hmmm... i'll try again

  • I'll try to send another log file tomorrow
Roboman's picture

another log file

i sent another log file.  it didn't return any rx errors this time but the arduino process only seems to output data to the arduino when i turn the pwm pin on or off, changing the value does nothing and it doesn't output any pwm signal. i know my arduino mega is not the problem because it worked before and i just tested the pins using a simple arduino sketch.

GroG's picture

Still did not get it....

For some reason when you send me a log file, I don't get it...

Is your MRL installed in a path which has spaces in the name ?

Did you recently download a full release .zip ?

Did you install the latest MRLComm.ino ?

Roboman's picture


i must be doing something wrong with sending the log files then. it is installed correctly and i am running the latest MRLComm.ino. i also just reinstalled MRL two days ago to see if that was the problem. this is a strange problem...

GroG's picture

100 ways to skin a kitty....

please email me the myrobotlab.log  

supertick (at) gmail (dot) com...


Roboman's picture

Log File

I,ve sent the log file, I quickly glanced trough it and i found a few lines that seem to be the problem;

375836 [arduino] WARN  class org.myrobotlab.framework.Service  - Arduino.analogWrite(IOData) :  NoSuchMethodException - attempting upcasting
375836 [arduino] WARN  class org.myrobotlab.framework.Service  - ouch! need to search through 209 methods
375836 [arduino] ERROR class org.myrobotlab.framework.Service  - did not find method - analogWrite(IOData)

they repeat themselves very often as I changed the pwm slider in the GUI, I've never really analyzed log files before so I don't know but these seemed interesting.

GroG's picture


Yes .. YOU FOUND IT !!!

IOData was optimized out as a parameter ... 

Fixed in build 1587 .. which is cooking as we type !

Nice Job... Thanks !

Roboman's picture



I'm glad I could help! Thanks for all your support Grog!!

GroG's picture


I'm guessing its working for you ?  If so that's great .. we're a good team .. high five o/