GPIO-MetaWear issue

edited July 2017 in Android


We are using 3 MetaMotionR sensors.  We
are trying to use the GPIO ports using MetaWare APP (android), to be sure that
it is not  a problem of our APP developed.

0 is used as an input (form analog circuit to the sensor), reading an analog
signal from 0 to 2.5V.

1 is used by Output, putting an UP (3v) to control the system.

is work properly for 5-8 minute, but suddenly it stop to capture in port 0 and it doesnt work again. I
thought that was some error with my electronic circuit, so I use “pull Mode”
and I see that after some minute the sensor is stoped the load the port. I have
check the accelerometer in order to be sure that was not a error of the
microprocessor, and it is working.

I want to use the sensor to load again or use the port, I have to reset the sensor.

have the same issue with all the sensor.

could you help me with this issue? 

Thanks in advance,



  • What sensor are you attaching to the GPIO pins?  The MetaWear app samples at 30Hz so you may want to try reducing the sampling frequency.
  • Hi Eric,

    Thank you very much
    for your response.

    I am attaching a
    strain gauge. Is very simple, I connected the Gauge to an amplifier to guarantee
    the dynamic range of the gauge from 0 to 3V whwn I measure different weigth. The changes are very slow (500ms-1000ms),
    but maybe if we can change the sample frequency, the app work properly, do you think so?

    Is it possible to increase
    the app samples? I mean, do you think the app is collapsing because I'm reading
    an analog input?

    Best regards,  

  • Yes, try reducing the sampling frequency to 2Hz (500ms).

    No, reading the analog input doesn't seem to be the problem but rather the frequency at which it is read.  30Hz is overkill if the sensor only changes between 1-2Hz.
  • Is it possible to change the frequency within the App? 

    Do you think that it is an issue in the app? or is in the FW? how I can test it?

    Thanks in advance, 
  • You will have to modify the app source code to change the sampling frequency.

    Ideally you should be using your own app anyways that is specifically built for your use case.  The MetaWear app is not a general purpose app to be used for all situations.
  • Thank you very much! 
    I will try to use it and I will keep you informed if it work. 

    Best regards, 
  • Hi, 

    We have done tests changing the frequency, but still after a while it is blocked. Any other ideas I can try?

    Thanks in advance,

  • Which frequencies did you test with and how long did it take before this issue occurred in your tests?  Also what Android device and OS are you testing with?

    Please post the code you are currently using.

    Try testing with another Android device or preferably an iOS device.
  • Hi, 

    I update the FW of the sensor and it look life it is working. 
    The only strange thing is the graphics. Apparently the sampling time does not match the actual measurement time, but at least now it is not blocking.

    We've only tested it with Android.

    Kwon with the new FW I have some issue to connect sensor with app (metawear). Is it normal? 

    Best regards,  
  • Please describe the connection issue in more detail, be specific.  Also, include the logcat output of when the issue occurs.

    I have not experienced any connection issues with firmware v1.3.4 so I cannot provide any specific suggestions other than general debug tips like :
    1. Reinstalling the app(s)
    2. Try with another device
    3. See if the board work with the nRF Connect app
  • Hi Eric, 

    I solve the issue connection going to Application management in the mobile phone, search MetaWear app, clear data, stop app. 
    Open again and scan--> connect.

    It look like is the phones that have the issue with the app.
    Phone used: Huawei P8 & Xiaomi Readmi note3

    Best regards, 

This discussion has been closed.