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CC2650 Movement Data Freezes

Derek Metcalf
Prodigy 20 points
Other Parts Discussed in Thread: CC2650, TS5A3159A

We are connecting our sensortag to the provided android and iOS apps and movement data graphs and data freeze within the app. Sometimes this occurs seemingly randomly and other times it will occur when locking then unlocking the phone. We can get the movement to enable again by disconnecting and reconnecting to the tag.

  • 0
    Prodigy 80 points
    Has anyone noticed this as well?

    If I leave the battery off for a long time, I see the accelerometer, magnetometer and gyroscope values update properly. After several minutes it stops updating, while the other sensors continue to update. I have to restart the CC2650 SensorTag and reconnect for it to work again. Over time, it stops updating sooner to the point where it stops updating within seconds. Then I have to take the battery off and walk away from it. I'm not sure whether this is a bug or I have a defective unit. This has been going on since the day I got the SensorTag.
  • 0
    TI__Guru** 105180 points
    Hello Derek,

    Can you list the smart app version and phone make/model?

    Best wishes
  • 0 in reply to JXS
    Prodigy 80 points
    Hi JXS,

    While we're waiting for Derek to respond here is my info. I'm running version 4.1 (build 142) from the Apple store on an iPhone 6 (iOS 8.3). I've also tried it on a Samsung Galaxy S4 (Android 4.3). It works fine until the motion sensors stop sending data. The other sensors continue to work ok. I think the issue is in the device.

    Thanks.

    Mark
  • 0 in reply to JXS
    Prodigy 20 points
    We tried two devices -- TI SensorTag version 4.1 on the iPhone 6 and TI SensorTag version 2.20 on the HTC One m7. Both exhibit the same error, exactly what Mark described above.
  • 0 in reply to Derek Metcalf
    Prodigy 70 points

    Hi Derek -

    For me, these issues always disappear with a fresh CR2032 battery.  The more sensors being monitored, the quicker the battery begins to fail.  If I run it for a few days on all sensors, it will get into a state like you described.

    Jeff.

  • 0 in reply to Jeff Durnwald
    Prodigy 80 points
    Interesting observation, Jeff. I thought it may be a battery issue as well, so I checked the voltage. It was 3.1v. Considering its a 3v battery, I figured it can't be low battery. I have some 3.7v coin cells I can try.

    Mark
  • 0 in reply to Mark Gonsalves
    Prodigy 80 points

    Seeing a similar issues here - movement stops, other sensors continue to send. Seems to be worse in 1.01 firmware than 0.91.

    Using our own app on Max OS X, and the iOS app, sometimes just the mag stops sending new values (with FW 0.91), and sometimes the whole movement data stalls (FW 0.91 and 1.01).

     iPad Mini II, iOS 8.2, SensorTag app 4.1 and MacBook Pro, Mac OS X 10.9.5. SensorTag HW 1.2

    Similar problems on two different SensorTags. Awaiting new batteries to see if that helps.

  • 0 in reply to Richard Polfreman
    Prodigy 80 points

    Put in new (CR2032) batteries and everything seems OK here, with both firmware versions, with iOS and Mac OS X. Will be interesting to see how long these last. Those supplied with the evaluation kit didn't last very long at all!

  • 0 in reply to Richard Polfreman
    Prodigy 80 points
    I ran a test. Started with battery at 3.1v. Let it run for a long time and noticed that movement data is no longer updating. Checked battery level. It is 2.9v. if I let the battery sit around unused, the voltage level creeps back up. In 10 mins it is up to 2.95v. That explains why we were seeing it work for short periods of time after the initial failure. So I bet the movement sensor requires a certain min voltage to function properly. I've seen this with other sensors.

    Mark
  • 0 in reply to Mark Gonsalves
    TI__Mastermind 29650 points
    Mark,

    Thanks for the feedback.
    I checked the data sheet of the sensor (store.invensense.com/.../MPU9250REV1.0.pdf) and it is specified down to 2.4V minimum. There might be a chance that as the battery nears EOL you have voltage drops that goes below 2.4V causing the sensor to reset while the CC2650 thinks it is still enabled and configured.

    Would you be able to connect a constant DC voltage supply or 2xAA batteries to see if the problem goes away or is reduced? We might need to set some limitations in the SW for what output data rates can be used in the sensor when running on a small coin cell.

    Regards,
    Svend
  • 0 in reply to svendbt
    Intellectual 535 points
    Hi,
    Do we have any solution to this. I am facing this issue in all the sensor tags (5 of them) I have bought. The sensor tag works with external power supply (regulated one) but keeps freezing after some reading when used with CR2302.
    The battery I am using is showing 3.0V. This is a new battery. One more observation is that the issue becomes more prominent on decreasing the sampling time to 50ms or 20ms.
    1. I am suspecting that there is blip in the voltage at the output of the switch U2 (TS5A3159A YZPR). Is there any way on the board to bypass this switch?
    2. I dont see the option of enabling/disabling DC-DC option in the senortag code. Please let me know how I can I try disabling the DC-DC in the chip.
    3. Please give any other suggestion which can help us to debug this issue.
    4. I want to use only MPU9250. So is there any straight forward way to disable all the other sensors (temperature, humidity etc). This may help in reducing the drawn current as the issue seem to be because of high current drawn during high sampling rate.

    Has this sensor tag been tested with 20ms/50ms sampling period?

    Regards
    Puneet
  • 0 in reply to Puneet Wadhawan
    TI__Mastermind 29650 points

    Puneet Wadhawan said:
    I am suspecting that there is blip in the voltage at the output of the switch U2 (TS5A3159A YZPR). Is there any way on the board to bypass this switch?

    It is a known issue that movement data freezes when the battery voltage drops below 2.4V since this is the minimum supply for MPU9250. We are implementing a workaround for this in the next SW release.(July)

    Puneet Wadhawan said:
    I dont see the option of enabling/disabling DC-DC option in the senortag code. Please let me know how I can I try disabling the DC-DC in the chip.

    This is done in customer config (ccfg.c / ccfg_appBLE.c) which is in the last page of flash. The SensorTag project does not include this file in the default build since the SensorTag has a flash loader program located in the last page of flash as well to allow OAD support. This flash loader is unfortunately not provided in source version until the July release so adding ccfg.c to the project will erase the flash loader and remove OAD support for now.

    .:Svend

  • 0 in reply to svendbt
    Intellectual 535 points
    Hi Svend,
    Thanks for a quick reply. When you say battery voltage falls below 2.4V is it a blip in the voltage due to high current drawn? I can see that the battery is measuring 3.0V.
    How do you explain it happening more often at higher sampling rate?
    In relation to the same question, I can see that MPU-9250 VDD is connected with MPU PWR (pin 18) of CC2650. I am guessing this is SW driven power. Is this a SW implemented functionality which is causing this issue ?
    Can I get the timing diagram of MPU PWR signal w.r.t SDA HP and SCL HP signals?
    Regards
    Puneet
  • 0 in reply to Puneet Wadhawan
    TI__Mastermind 29650 points
    Coin cells have high internal resistance when they start to wear out so a current peak will cause the supply voltage to drop momentarily causing the MPU to reset. If you measure the unloaded battery afterwards you might still see it being almost 3V.
    There are probably also some internal resistance in the driving I/O which reduces the supply head room a bit.

    .:Svend
  • 0 in reply to svendbt
    Prodigy 230 points
    I am facing a bit different issue with motion data.

    I am working with a beacon device and TI Sensortag cc2650 to read the sensortag data on beacon device using gatt. I am all done with humidity,IR temperature and light sensors. How can I enable the Gyro and Accelerometer sensor bits?

    For above completed sensors I successfully wrote 1 to WriteCharacteristic and it turned all sensors up and showed me the RAW values for every sensor but not for Gyroscope and accelerometer sensor (MPU-9250). I went through some forums and found that we need to enable 3 different bits i.e;

    { Axis enable bits:gyro-z=0,gyro-y,gyro-x,acc-z=3,acc-y,acc-x,mag=6 }

    Range: bit 8,9

    How can I enable these bits or pass these bits to WriteCharacteristic in order to enable these?
  • 0 in reply to svendbt
    Intellectual 260 points
    When exactly in July is a new firmware supposed to be released ?
    this is a really annoying and we need to go through a lot of batteries to get some work done with these sensortags
  • 0 in reply to svendbt
    Prodigy 150 points
    Hello svendbt

    I was experiencing this issues of movement data freezing described in this post. As I have the Simplelink SensorTag DevPack, I removed the battery from the SensorTag and connected it to the DevPack, the DevPack to the computer (via USB). The movement data does not freeze anymore, after several tests.

    Maybe it is obvious but I thought it could be useful, also for the rest of the people having the issue, now it is clear that the data freezing issue is related to the battery, right? By the way, are you planing to release a firmware version/app that solves this problems (maybe with the SW restrictions you were talking about)?

    Thanks and regards
    Borja
  • 0 in reply to Borja Velasco
    Prodigy 150 points
    Okay, I am new to the forum and I hadn't seen all this posts before, they appeared when I posted my reply, so don't bear in mind.
  • 0 in reply to svendbt
    Prodigy 150 points

    I have a question regarding how the MPU9250 is powered.

    It seems like it is being powered by an I/O from the CC2650 instead of an LDO.  And they didn't even use one of the high powered I/Os.

    According to the schematic, VDD is connected to MPU PWR which is driven by pin 18 DIO_12.

    Doesn't this seem weird, especially since the I/O is rated for 4 mA and the MPU9250 typical current draw is 3.7 mA?

    Lee

  • 0 in reply to svendbt
    Intellectual 535 points
    Hi Svend,
    When is the the SW workaround to this issue getting released? We need to fix the issue as we are facing difficulty while capturing data for our specific usecase.
    Regards
    Puneet
  • 0 in reply to Puneet Wadhawan
    Intellectual 535 points
    Hi Svend,
    Please send me the link of the firmware (with the fix) if it has been released.
    Regards
    Puneet
  • 0 in reply to Puneet Wadhawan
    TI__Mastermind 29650 points

    Hi Puneet,

    http://ti.com/blestack -> BLE-STACK-2-1

    Regards,
    Svend