Chagrin:
Figure 14 (Page 12) of the PCA9544 datasheet shows the wiring. You would power the PCA9544 with 3.3V and the pull ups on the Mega will keep that side of the I2C bus at 5V. The MPU-9150 buses would need 3.3V pull ups and everything should be kosher. I'd appreciate if CrossRoads or Grumpy would chime in on that though.
Thank you fro your reply.
With this setting, I can have only one PCA 9544 and eight MPU-9150s, but no voltage level translator. (Because the MPU-9150 can have two different address, 2 MPU-9150s can be connected with one I2C bus.)
The MPU-9150 breakout that I have, already has the pull-up registers:
I saw it somewhere, but is it OK to use the pull-up registers in Arduino Mega 2560 (SCL and SDA for 5V) or should I need external ones?:
(P.S. I don’t mean to be picky, but the Figure 14 (Page 12) of the PCA9544 data sheet says « VDD ». Maybe I don’t have to worry too much and I can connect 3.3V Pin of Arduino to this, but just in case, do I have to concern about FET drain, especially in this case?)