Wiring for Arduino Mega and multiple MPU 6050/Gy 521?
MPU-6050 uses I2C for comm's, yes?
Connect all the SCLs in parallel to the Mega with a 4.7K, or 3.3K, pullup resistor. Same for the SDAs. I2C is D20, D21 (or D21, D22) on the Mega.

The MPU-6050 has an A0 pin to select from one of two addresses, let's call them Add0 and Add1 for simplicilty.
Connect each MPU-6050 A0 pin to a unique Mega pin.  When none are being addressed, have each Mega output high. When one MPU-6050 is to be accessed, take that device's A0 pin low and communicate with it using Add0. The other's will be looking for communications at Add1 and thus will not respond.

If the MPU6050 is a 3.3V device, then you should also remove the pullup resistor network package on the Mega that pulls SCL/SDA to 5V.  There are 2 pullups in a very little 8-pin package, the other 2 are not used. Connect the 3.3K or 4.7K pullup resistors discussed above to 3.3V.



This is the part, RN1, on the Mega R3 board. It may not be marked as such on the board. Remove it, or cut the traces next to the pad legs, one on the left side (connects to pin 3), one on the top (connects to pin 2).