MPU-9150 (IMU) AD0 address change
(For consistency with your numbering, I'll count the 3 pads of the AD0 jumper starting with pad 1 on the left-hand side.)


  as I understand it I need to "desolder" the connection from 2+3 and then I can connect VCC to pin AD0 which will switch the address to 0x69. I tried desoldering, but it looks like this won't "break" the connection even if I get rid of all the solder, it looks like it'll be still connected due to the little "circle" and the edges around it 


Agreed. That breakout board for the MPU9150 seems to have a design defect and some kind of square-ish through-hole pad is bridging the right-hand pair (pads 2-3) of the 3-pad AD0 jumper. I've marked it in green on this enlargement from your image, for readers to see what I'm referring to:



People with the necessary experience, tools &amp; perhaps some magnification, could bypass those pads, cut the PCB track leading from pad 2 to the AD0 pin on the device, and connect the track however is required (logic high or low).

If you want to use those 3 pads of the AD0 jumper, you'll need to investigate the purpose of that square-ish through-hole pad - does it have any connections, top or bottom, except to AD0 jumper pads 2-3? I expect the square-ish through-hole pad has a connection to Gnd. If so, you'll need to use a sharp knife (scalpel) to cut away the copper from that square-ish pad which connects it to pad 2 on the AD0 jumper, leaving it only connected to pad 3.


  What happens if I'd solder AD0-jumper 1+2 together?


Do not connect pads 1-2 of the AD0 jumper until pads 2-3 are definitely disconnected, otherwise you will short pad 1 (VLOGIC) to pad 3 (Gnd).

You should really get support for this PCB problem from the vendor of the breakout board. Unfortunately a low-cost supplier may not care, and in that case, you would have the challenge of solving this yourself.



After the incorrect copper "bridge" has been removed between pads 2-3, then the following options are possible: 

If you want to use the AD0 pin on the 0.1" header to select the I2C address, then the AD0 solder jumper must not connect the centre pad (pad 2) to either of the other pads.

Alternatively, if you want to fix the I2C address on the board without using an external connection to the AD0 pin on the 0.1" header, then:


connecting AD0 solder jumper pads 1+2 (pad 3 unconnected) sets AD0 high (I2C address 0x69), or
connecting AD0 solder jumper pads 2+3 (pad 1 unconnected) sets AD0 low (I2C address 0x68)