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Topic: MD 25 motorcontroller I2C address (Read 321 times) previous topic - next topic

jumping-hotdog

Feb 20, 2018, 09:13 am Last Edit: Feb 20, 2018, 09:25 am by jumping-hotdog
Hey there,
I'm working on an old robot project in school that uses this motorcontroller. My problem now is that it does not react to any I2C communication. Even if I'm scanning for I2C addresses I can't find it.

It should be flashing it's address after turning on the voltage, but it doesn't. The projects in the past all used serial communication and worked. I already removed the jumpers but that didn't help.

Unfortunately the old circuit had some problems and does not work anymore and the students as well as the teachers who built this robot left our school two years ago.

Does anyone have a doubt what I'm doing wrong?

TomGeorge

#1
Feb 20, 2018, 11:05 am Last Edit: Feb 20, 2018, 11:06 am by TomGeorge
Hi,
Do you have a link  to data/specs of the MD25?

How are you trying to communicate with it?

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

TomGeorge

#2
Feb 20, 2018, 11:08 am Last Edit: Feb 20, 2018, 11:11 am by TomGeorge
Hi,
I think this is the controller;

https://www.robot-electronics.co.uk/htm/md25tech.htm


Have you tried serial comms mode?

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

jumping-hotdog

yes, that's the right one.

No, I hven't tried serial yet, but I will tomorrow. Is there any register that indicates if the controller is using I2C or serial to communicate?

I've found a program example online that is scanning for I2C addresses and worked well with my sensor. When I tried to find out the address of the controller it didn't work but also didn't give back an error. What confused me the most was that the LED for TRX on the arduino was not flashing...


TomGeorge

Hi,
Have you got the Serial/I2C  jumpers set correctly?

Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

jumping-hotdog

Hi,
yes, I'm pretty sure. I removed both of them. Do I have to change the baud-rate in my program?

jumping-hotdog

Hi,
we solved the problem by mistake now. My teacher misused the multimeter and made a short-circuit with it but now it works. We still have no clue what has been the problem. We have a second controller which we tried out but it has the same problem. (we didn't test our special reparing methods again  :smiley-wink: )

We realised that our voltage regulator got quite warm althoug we had the wheels spinning without resistance and not very fast. What current can we expect at half of the speed?

TomGeorge

We realised that our voltage regulator got quite warm althoug we had the wheels spinning without resistance and not very fast. What current can we expect at half of the speed?
What are your motors, how many?
Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

jumping-hotdog

:) good question. A EMG30 with encoder. The nominal current should be 530mA. Our voltage regulator should provide 3A due to the datasheet. We are going to place a heat sink on it tomorrow and see what happens.

thank you for your help so far :)

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