Hi, I am trying to use the BMA400 to detect the swings of a tennis racket. And I was wondering if its possible to simply configure the registers (0x59 to 0x70) that are used for step-counting and set them in a way to detect this activity instead. Right now in the datasheet (bst-bma400-ds000.pdf) the settings for these registers are mysterious. I was wondering is there a description of exactly what the meaning of each of these registers is?
Basically I want to go from a sample acceleration waveform to a corresponding setting of STEP_COUNTER_CONFIGX that will let me detect that waveform. Is that possible? Or must I implement alternative activity detections in software.
Thanks for your inquiry.
BMA400 step counter is not designed for the motions of swings of a tennis racket. It is mainly used to count how many steps a person has walked. If you want to analysis how the swing of a tennis racket looks like, then you may consider using BHI260AB + BMP390 smart sensorhub plus a pressure sensor sampling at 200Hz or above.
Thanks for your reply, a few followup question:
1. could you say a little bit more about why a pressure sensor is needed in addition to an accelerometer+gyro for this project.
2. I was wondering if you could share whether its possible to configure the registers in a BMA400 to detect any activity other than walking ? Like rope skipping, or doing lunges, squats etc. ? I was hoping that that the registers can be configured to make the BMA400 detect some closely related activity as well by just making a few small changes. I am okay with experimenting and doing trial and error to fine tune new register values but that will need some understanding of what each register does.
When tennis racket swings the height will change. So a pressure sensor BMP390 is able to give you information how the racket moves from low to high or from high to low in real time. BHI260AB is able to give you information about how the racket rotates in real time.
If you want to recognize some motions like lunges, squats, etc. then BMA400 is not enough. BMA400 is just a pure accelerometer that measures all mixed accelerations such as linear acceleration, gravity and centripetal acceleration, etc. You may consider BHI260AP sensor that has AI algorithm running inside for cyclic gesture recognition.