I want to start by saying I've never made a forum post before, so I'm sorry if I mess anything up.
I have been working on the same problem with my new MPU-6050 unit for several hours, and I have not found any online solutions that address my problem. I am using the GY-521 module, with a knockoff Arduino Nano that has worked well in the past. The GY-521 has a built-in voltage regulator, so it should be able to take 5V, but I also tried it with 3.3.
The specific issue that I am having is that the MPU-6050 shows up when I run an I2C scan (the one found here), but the library I'm using (found here) has trouble connecting properly.
When I run the scanner, I get the message:
Scanning...
I2C device found at address 0x68 !
done
Which is exactly what I would expect to see.
However, when I try to run the DMP6 example sketch from the library, I get:
Initializing I2C devices...
Testing device connections...
MPU6050 connection failed
Send any character to begin DMP programming and demo:
Now, when I run the "raw" sketch from the same library, I get output that looks valid to me. When I rotate the sensor in the x direction, the corresponding value changes in the way that I expect. However, I would like to use code that gives me more useful output while also offloading from my Arduino's processing, so I want to use the DMP code. Also, the same "MPU6050 connection failed" message appears for the raw sketch too. I tried inputting a character at the prompt for the DMP sketch, but then it gets hung up on:
Resetting memory bank selection to 0...
******* etc.
The AD0 pin is grounded, so it makes sense that the address is 0x68, which I believe is the default in the MPU-6050 library. SDA goes to A4 and SCL goes to A5. I tried tying the INT pin to D2 as suggested, to no avail, and I tried adding 10K pull-up resistors to SDA and SCL, with no effect.
I would very much appreciate any insights you might have. I can post my wiring if you think it's needed, although the fact that it showed up on the I2C scanner makes me think it isn't. Thanks!