MMR-Not able to connect in particular orientation

Hi, I am using a MMR sensor.
I am using a python script to connect to the MMR to stream Quaternion values. The sensor seems to be working fine. But after few minutes, the sensor stops streaming data while moving along one particular orientation, mainly motion along the +Z axis.
Also, the sensor is able to connect to the device while placed on the table. But when I have device attached to my arm and have the arm up to my shoulder level, and try to initiate the connection it fails. Also, at the same time, while the connection sequence is running if I bring my arm down, the connection is successful.

I have tried this with 3 sensor, and I am facing the same issue. Any idea why this might be happening? The firmware on the device is 1.5.1

Please let me know if you need more information


  • hey I saw a similar issue. Was this happening with the same sensor with firmware 1.5.0? Is this new for you?

  • Hi Laura,
    I don't recall having this problem couple of months back. And I guess during which I had 1.5.0 firmware. I had recently updated the firmware in all my sensors. And noticed this was happening.


  • I noticed it too. I am going to check it out. It could be the default antenna gain in 1.5.1 is low and you can just use the API call to set it higher: mbl_mw_settings_set_tx_power()
    Have you tried that?

    edited March 2021

    Hi, I just gave it a try.
    I set the parameter libmetawear.mbl_mw_settings_set_tx_power(self.device.board,4).
    It seems to be working now when I tried for a couple of times. I will update if I noticed the same issues again later today

  • OK I bet that the default settings in 1.5.1 are too low. Let me look into this but you have a workaround for now :)

  • @Laura said:
    OK I bet that the default settings in 1.5.1 are too low. Let me look into this but you have a workaround for now :)

    Hi Laura,

    I just noticed this tx power issue and learnt that I can adjust the power from your answers in another post. I am wondering what is the proper tx power for streaming from Acc (100 Hz), Gyro (100 Hz) and Mag (25 Hz) simultaneously? Can you provide some suggestions?


  • There's no right or wrong. You might as well blast the maximum when you are doing something important. The only tradeoff is battery life of course.

  • Hi Laura,
    I am facing the same issue...
    any plans for new firmware release?

  • So it's the default settings of BLE 5.0 that sets the initial tx mode to a low setting. We unfortunately can't do anything about that but you can still use our API call to set the tx mode higher.

  • Hi Laura,
    Thanks for the update.
    But even setting the tx mode higher the issue still exists. Previously, before increasing the TX, the sensor wouldn't start while placed at a specific orientation. But now, while moving the sensors around, it stops while it reaches the specific orientation.
    If you need some plots or more information please let me know.

  • Can you please send more info. Is this replicable? Sounds very odd like maybe in an orientation of some kind there is interference? I don't have any information to comment more but would appreciate pics/details.

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