Bosch Sensortec Community

    Showing results for 
    Search instead for 
    Did you mean: 

    BMI270 Wrist Wear Wakeup Angle Definitions

    BMI270 Wrist Wear Wakeup Angle Definitions

    New Poster

    Hi.  I have been using the B270 and it is EXTREMELY user-friendly.  I am using it in a smart-watch application and the built-in features are outstanding.  Also this forum has really been a big help so thank you all!

    I have the Wrist-Wear Wakeup functioning but want to tweak the angles a bit.  The description in the datasheet are as follows:

     .min_angle_focus - Minimum expected change in attitude angle in a 1 second period when moving within focus position.
     Value is 2048 * cos(angle) (default: 1448 = 45 deg) Range is 1024 to 1774 (60 to 30 deg)

     .min_angle_nonfocus - Minimum expected change in attitude angle in a 1 second period when moving from non-focus position
     to the focus position. Value is 2048 * cos(angle) (default: 1774 = 30 deg) Range is 1448 to 1856 (45 to 25 deg)

     .max_tilt_lr - Maximum tilt angle to the right that defines the focus position.
     Value is 2048 * sin(angle) (default: 1024 = 30 deg) Range is 700 to 1024 (20 to 30 deg)

     .max_tilt_ll - Maximum tilt angle to the left that defines the focus position.
     Value is 2048 * sin(angle) (default: 700 = 20 deg) Range is 700 to 1024 (20 to 30 deg)

     .max_tilt_pd - Maximum tilt angle to the front that defines the focus position.
     Value is 2048 * sin(angle) (default: 179 = 5 deg) Range is 0 to 179 (0 to 5 deg)

     .max_tilt_pu - Maximum tilt angle to the back that defines the focus position.
     Value is 2048 * sin(angle) (default: 1925 = 70 deg) Range is 1774 to 1978 (60 to 75 deg)

    The issue I am having is understanding whick these refer to.  I will use the following figure.  This figure assumes the orientation in the datasheet for wrist wear wakeup i.e. 


    If we take a side view, I can define Y' and Z' as the coordinates of the observer.  a1 and a2 could be considered "tilt angles" relative to the observer. 


    Do these angles correspond to .max_tilt_pd or .max_tilt_pu?  If so, which is which?  If not, how would one adjust these angles?  

    Also, .min_angle_focus and  .min_angle_nonfocus are defined as rates of change of angles.  Again, which angles do they refer to?  


    Appreciate any help!



    5 REPLIES 5

    New Poster

    Anyone?  Bueller?,,,

    Community Moderator
    Community Moderator

    Hi Fishbone,

    From your second coordinate graph, it does not match the coordinates of Figure 3. This angle does not correspond to either. max_tiltpd or. max_tild_pu. We suggest that you take a video to see the parameters you need to adjust, or you redraw your coordinates based on the coordinates in Figure 3.

    Sorry for the delayed response.  I guess my figure was pretty bad.  It was an attempt to show a "side-view" of the person, looking down at their watch.  What I am trying to do is adjust the tilt angle the wrist must be at to have the wrist wear wakeup interrupt execute.  So the y and z in the figure correspond to the y and z of figure 3.  

    Let me ask another way.  Suppose I am standing with my arm in front of me and my wrist is oriented so that my watch face is straight up to the sky  like this:


    Now suppose I have the watch in front of me but tilted so that  when I look directly in front of me, the watch looks like it does in Figure 3 above or like this:


    How do I change this tilt angle?  Thank you in advance!!






    Here is another pic explaining the difference (I think this explains the "tilt" angle I am concerned with):