Examples for nRF51 & nRF52 and MPUxxxx
MPU examples meant to be used with Nordic's nRF51 or nRF52 ICs and SDK 11.0.0. This repository includes MPU hardware drivers for SPI and TWI. The drivers are located in nrf_drv_mpu_spi.c and nrf_drv_mpu_twi.c respectively. A library is running on top of the drivers. The library is located in app_mpu.h/c. By using the library the hardware driver is transparent to the application and it is easy to switch between SPI and TWI. Each of the examples, except the nrf52 easydma examples, have project files to use with bot SPI and TWI. For example: "nrf5-mpu-simple\pca10028\arm5_no_packs\spi\nrf5-mpu-simple.uvprojx". Note that MPU9150 does not support SPI.
Tested on:
- MPU9255
- MPU9150
- nRF51 DK (PCA10028)
- nRF52 DK (PCA10040)
- SDK 11.0.0
- SoftDevice S132 V2.0.0 and S130 V2.0.0.
- Not tested on PCA10036 and MPU60x0
How to use:
- All examples are made for SDK 11.0.0. Other SDKs will not work. Download the zip file and extract to "sdk_11.0.0_folder\examples". Or just clone it to the same folder.
- Define your MPU in Keil's "Target Options -> C/C++". Use define "MPU9255", "MPU9150", or "MPU60x0".
- Remember to define the correct TWI, SPI, and/or interrupt pins. The SPI and TWI pin defines are located in the nrf_drv_mpu_xxi.c files. The GPIOTE interrupt pin is defined in main.c.
Disclaimer
- The examples are not extensively tested and only meant as simple explanations and for inspiration.
- NO WARRANTY of ANY KIND is provided.
- There are probably several things that can be improved or added. E.g. the SPI and TWI transfer functions should be interrupt driven and not blocking like they are now.
MPUs
Quote on differences between different MPUs from Invensense: "The MPU-6050 is higher power, lower noise, and larger package versus the MPU-6500. Most of your code should port over, but some low power features are different and will need to be recoded in. Basic data acquisitions shouldn’t have changed.
The MPU-9150 contains the MPU-6050 and an AK8975 magnetometer from AKM. The MPU-9250 contains a MPU-6500 and AK8963. The same differences between gyro/accel are the same you see with 6050 v. 6500. The magnetometer on the MPU-9250 is a little better across the board."
These examples do not implement the AK8963, Digital Motion Processing (DMP), or any low power features.
More on the difference between MPU6050 and MPU9150: http://www.sureshjoshi.com/embedded/invensense-imus-what-to-know/