in these day i'm working on support of i2c ESC like a microkopter or VR i2C ESC.
So I'm doing a lot of test and check different situation on different configuration.
At this point i'm testing in flight my quad with VR I2C ESC .
There're some suggestions about the connection of i2c ESC as slave.
1) Connect the ESC using a series of 100 ohm resistor .
2) Using pullup of 4.7 k between the vdd and SDA and SCL pin .
3) For testing oly one esc is important that there'isnt the delay between the power up of esc and send first command to it.
If you using only one esc i see that is important to add in the hardware library in i2c.c the i2c_start_condition() and i2c_stop_condition() on the bus so the MP32 ignore the current status of the bus.
Other suggestion about i2c is welcome :)