Pag. 26 of the datasheet...
The MPU-60X0 always acts as a slave when communicating to the system processor. The LSB of the of the I2C slave address is set by pin 9 (AD0). The logic levels for communications between the MPU-60X0 and its master are as follows:
? MPU-6000: The logic level for communications with the master is set by the voltage on VDD
? MPU-6050: The logic level for communications with the master is set by the voltage on VLOGIC
Auxiliary I2C Serial Interface
The MPU-60X0 has an auxiliary I2C bus for communicating to an off-chip 3-Axis digital output magnetometer or other sensors. This bus has two operating modes:
? I2C Master Mode: The MPU-60X0 acts as a master to any external sensors connected to the auxiliary I2C bus
? Pass-Through Mode: The MPU-60X0 directly connects the primary and auxiliary I2C buses together, allowing the system processor to directly communicate with any external sensors.
Auxiliary I2C Bus Modes of Operation:
? I2C Master Mode: Allows the MPU-60X0 to directly access the data registers of external digital sensors, such as a magnetometer. In this mode, the MPU-60X0 directly obtains data from auxiliary sensors, allowing the on-chip DMP to generate sensor fusion data without intervention from the system applications processor.
For example, In I2C Master mode, the MPU-60X0 can be configured to perform burst reads, returning the following data from a magnetometer:
? X magnetometer data (2 bytes)
? Y magnetometer data (2 bytes)
? Z magnetometer data (2 bytes)
The I2C Master can be configured to read up to 24 bytes from up to 4 auxiliary sensors. A fifth sensor can be configured to work single byte read/write mode.
? Pass-Through Mode: Allows an external system processor to act as master and directly communicate to the external sensors connected to the auxiliary I2C bus pins (AUX_DA and AUX_CL). In this mode, the auxiliary I2C bus control logic (3rd party sensor interface block) of the MPU-60X0 is disabled, and the auxiliary I2C pins AUX_DA and AUX_CL (Pins 6 and 7) are connected to the main I2C bus (Pins 23 and 24) through analog switches.
Pass-Through Mode is useful for configuring the external sensors, or for keeping the MPU-60X0 in a
low-power mode when only the external sensors are used.
In Pass-Through Mode the system processor can still access MPU-60X0 data through the I2C
interface.
Auxiliary I2C Bus IO Logic Levels: MPU-6050: The logic level of the auxiliary I2C bus can be programmed to be either VDD or VLOGIC
I followed the istructions for the Pass-Through Mode:... on the chip is present an "interface bypass mux" and it shuold be the "analog switches" above cited. I don't know how I can read the aux-data.
THANKS for your reply!
MPU-6050.pdf (1.6 MB)