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TL;DR: is it safe to power a MPU 6050 module through its AD0 pin instead of VCC?

We managed to have two MPU 6050 modules on the same I2C buffer by changing the address of one of them by connecting its AD0 pin to the same current origin used for VCC.

We found out that we can get the same result if we just switch the power cable which goes to the VCC pin to the AD0 pin: the module changes its address and we are able to read its data normally.

This would be a better configuration for us because, if the AD0 cable ever got disconnected, we wouldn't get anything from the second module but we would still get uncorrupted data from the first one. In the other case (cable to both VCC and AD0), if the AD0 cable got disconnected, we would get corrupted data.

So the final configuration would be: GND, SCL, SDA pins connected normally, power to AD0, pin VCC left unconnected.

The question is: is this a safe configuration or is it better to just leave the VCC pin connected normally and get another cable to the AD0?

From empirical tests it looks like it works fine, but we couldn't find any confirmation and are not experts on the matter.

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Theoretically that should be OK.

According to the datasheet the MPU6050 consumes no more than 3.9mA with all the internal options turned on. That is below the limit of 25mA sustained current from a single IO pin for the ATMega chips. Just be aware of the total limit of the ATMega's power pins of 200mA, but it would take a lot of modules to reach that limit.

Since the MPU6050 is a 3.3V device your modules most likely have a voltage regulator on them to allow powering from 5V. That should mitigate any voltage droop caused by the higher impedance of using an IO pin as a voltage source.

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