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10 years, 5 months ago.

Question about the communication between MPU6050 and nrf51822

Hello, I modified the sample code BLE_HeartRate to add the function:read the data from MPU6050 by hardware I2C，then transfer the temperature (and some other data,such as acceleration)and HRM to iPhone5.The app is designed by nordic(The name seems to call nrf toolbox?)and lightblue. Firstly,I only read the temperature and transfer to the iPhone.It can work and the data is correct.The timing diagram of I2C is shown as follows:

/media/uploads/youyou/i1.jpg

It is normal.But after some time,about 6 minutes or less,the I2C signal will be disappear. The phenomenon is shown as follows: /media/uploads/youyou/i2.jpg

The SCL is always high and the SDA is always low.What happen? I test the MPU6050 library and I2C library(mbed),don't use the BLE,just print the data by serial port.It is OK.But when I use the BLE,the I2C will be abnormal after some time. Is it possible the bug between the BLE and I2C hardware? Somebody say that if you use BLE,you should use the software I2C.It can not work if you use hardware I2C.Is it right? By the way,when I2C is abnormal,I must cut off the power and reconnect the power,it can work for some time.If I just reset the nrf51822,but it can no effect.Very strange!

Please help me.Thank you!

Question relating to:

Last updated: 27 Aug 2020
The nRF51822-mKIT is a low cost ARM mbed enabled development board for Bluetooth® Smart designs with the nRF51822 SoC. The kit gives access to all GPIO pins via pin headers …

Program URL:http://mbed.org/users/youyou/code/BLE_temperature/

posted by youyou yu 10 Jun 2014

Why nobody answer this question?

posted by youyou yu 17 Jun 2014

3 Answers

Daniel Litvak
9 years, 4 months ago.

Were you able to get this working? I am trying to simply read the data from the MPU6050 and transfer it via BLE to my phone. Do you have any working example code?

CJ Shaw
8 years, 4 months ago.

This seems similar to all the bugs with nRF51822 + mbed that are currently falling under the "multiple ticker" issues.

I don't think this is solved. I have a possibly related bug/question listed here: https://developer.mbed.org/questions/69710/Tickers-crashhang-on-the-nRF51822-especi/

Recently I've noticed very similar things to what you've described happening to my I2C comms when what we're currently calling the "multi-ticker problem" hits. I'm not sure if I2C going berserk is a symptom or cause of the issues...

If you made any progress on this before then please let me know. Thanks.

erkin yucel
8 years, 1 month ago.

I am having same problems while getting data from MPU9250 with I2C. If I use BLE and I2C, after 400 - 500 secs both BLE and I2C down.

If you made any progress please let me know. Thanks.