Document Number: PS-MPU-6500A-01
Revision: 1.1
Release Date: 03/05/2014
MPU-6500 Product Specification
4.9.2 MPU-6500 Solution Using SPI Interface
In the figure below, the system processor is an SPI master to the MPU-6500. Pins 8, 9, 23, and 24 are used
to support the CS, SDO, SCLK, and SDI signals for SPI communications. Because these SPI pins are
shared with the I2C slave pins (9, 23 and 24), the system processor cannot access the auxiliary I2C bus
through the interface bypass multiplexer, which connects the processor I2C interface pins to the sensor I2C
interface pins. Since the MPU-6500 has limited capabilities as an I2C Master, and depends on the system
processor to manage the initial configuration of any auxiliary sensors, another method must be used for
programming the sensors on the auxiliary sensor I2C bus pins 6 and 7 (AUX_DA and AUX_CL).
When using SPI communications between the MPU-6500 and the system processor, configuration of
devices on the auxiliary I2C sensor bus can be achieved by using I2C Slaves 0-4 to perform read and write
transactions on any device and register on the auxiliary I2C bus. The I2C Slave 4 interface can be used to
perform only single byte read and write transactions. Once the external sensors have been configured, the
MPU-6500 can perform single or multi-byte reads using the sensor I2C bus. The read results from the Slave
0-3 controllers can be written to the FIFO buffer as well as to the external sensor registers.
For further information regarding the control of the MPU-6500’s auxiliary I2C interface, please refer to the
MPU-6500 Register Map and Register Descriptions document.
Processor SPI Bus: for reading all
data from MPU and for configuring
MPU and external sensors
Interrupt
INT
Status
Register
nCS
nCS
SDO
MPU-6500
SDI
Slave I2C
or SPI
Serial
Interface
System
Processor
SCLK
SDI
SCLK
SDO
FIFO
Sensor I2C Bus: for
configuring and
reading data from
external sensors
Config
Register
Optional
Sensor
Master I2C
Serial
AUX_CL
AUX_DA
SCL
SDA
Sensor
Register
Interface
Bypass
Mux
Compass
Interface
Factory
Calibration
Digital
Motion
Processor
(DMP)
I2C Master performs
read and write
transactions on
Sensor I2C bus.
Bias & LDOs
VDD
GND
REGOUT
Figure 7: MPU-6500 Solution Using SPI Interface
Note: The Interrupt line should be connected to a pin on the Application Processor (AP) that can bring the AP out of suspend
mode.
4.10 Auxiliary I2C Serial Interface
The MPU-6500 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-6500 acts as a master to any external sensors connected to the
auxiliary I2C bus
Pass-Through Mode: The MPU-6500 directly connects the primary and auxiliary I2C buses together,
allowing the system processor to directly communicate with any external sensors.
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