Basic question about adresses for LEGO breadboard adapter

Hi there,

sorry this is probably a silly question but I am trying a basic program to get information from an arduino accelerometer to my mindstorm EV3.

I am using this EV3 program :

with my arduino UNO connected to the Accelerometer using the analogread.ino program with default settings.

it turns out that I never get any information to the EV3, apparently because the arduino never gets requested anything.
This is my frst application and I thought I made everything as indicated on the tutorial ( so I cannot find what is wrong.

Do I have to change the adress or PIN parameter (address is on 4 and PIN on 1 and my wire is on A1) or do I have to check connections… My battery is very low on the EV3, could it explain the problem ?

Many thanks for any advice on this :smile:

Just to add some détails :

  • I tried adding 47K pullup résistors
  • I tried other addresses as I read that <8 could not work : 8 and 15
  • I used charged batteries

Nothing happens : it looks like the adapter does not work… what do I do wrong ?


Hi there,

I finally found what was wrong, by browsing the forum… the two switches must be put up… very classic problem I am not the first one to encounter, nor the last I fear.

So guys, maybe you should consider putting these up by default or letting a note in the package (all I had was a tiny note I did not keep… if it was on it consider making it more visual).

Great to have it running though. Keep up the good work !

@Matt, could you jump into this one?

Thank you!

I2C does require pullup resistors. The breadboard breakout offers these resistors with switches to enable/disable them (as you realized). The breadboard breakout can be used for more than just I2C, and most other applications don’t require pullups (or will actually fail with pullups). Instead of using the pullups and switches on the breadboard breakout, you could add resistors to the breadboard. Note that most sensors (as well as some Arduinos) already have I2C pullups, and by having two sets, they could be too strong.