BMX160 Step Detection

[Nikosant03]

Hi everyone,

I want to configure BMX160 for step detection for human beings. The sensor will be placed inside the insole.

Could you please help me to configure the parameters for min_steptime and min_threshold in order to achieve a robust step detection? I cannot find any information for those parameters into the datasheet.. The only info I can find is regarding the working mode (Normal, Sensitive, Robust) and there is no information regarding the bits on registers 0x7A - 0x7B (see 2.11.37 pg 88)

This is my configuration so far

void stepDetector_set(struct bmi160_dev *dev) {

  int8_t rslt = 0;

  /* Select the Interrupt channel/pin */
  int_config.int_channel = BMI160_INT_CHANNEL_1; // Interrupt channel/pin 1

  /* Select the Interrupt type */
  int_config.int_type = BMI160_STEP_DETECT_INT;

  /* Select the interrupt channel/pin settings */
  int_config.int_pin_settg.output_en = BMI160_ENABLE;         // na - Enabling interrupt pins to act as output pin
  int_config.int_pin_settg.output_mode = BMI160_DISABLE;      // na - Choosing push-pull mode for interrupt pin
  int_config.int_pin_settg.output_type = BMI160_ENABLE;       // na - Choosing active High output
  int_config.int_pin_settg.edge_ctrl = BMI160_ENABLE;         // na - Choosing edge triggered output
  int_config.int_pin_settg.input_en = BMI160_DISABLE;         // na - Disabling interrupt pin to act as input
  int_config.int_pin_settg.latch_dur = BMI160_LATCH_DUR_NONE; // na - non-latched output

  int_config.int_type_cfg.acc_step_detect_int.min_threshold =                                 // ??????
  int_config.int_type_cfg.acc_step_detect_int.step_detector_en = BMI160_ENABLE;           // na - 1-enable, 0-disable the step detector
  int_config.int_type_cfg.acc_step_detect_int.step_detector_mode = BMI160_STEP_DETECT_NORMAL;  // na - Set Normal Mode
  int_config.int_type_cfg.acc_step_detect_int.step_min_buf =                                  // ??????
  int_config.int_type_cfg.acc_step_detect_int.steptime_min =                                 // ??????

  /* Set the Step Detector interrupt */
  rslt = bmi160_set_int_config(&int_config, dev); /* sensor is an instance of the structure bmi160_dev */

  if (rslt != BMI160_OK) {
    //printf("BMI160 Step Detector interrupt configuration failure!\n");
  } else {
    //printf("BMI160 Step Detector interrupt configuration done!\n");
  }
}

Thanks in advance

Nick

[BSTRobin]

Hello Nikosant03,

Which mode did you use? If it is sensitive for you, you could choose normal mode robust mode for your application.

[Nikosant03]

Hi BSTRobin

I tried all the modes (sensitive/normal/robust) but I have the same problem. When I jump an interrupt is generated... Actually this makes sense since the step detection interrupt is based on the accelerometer. I suppose that while jumping I exceed the predefined accel's threshold and that's why the interrupt is generated. How could I work around this issue since I do not want to interrupt while jumping (it is not a step 😀)?

Thanks for your assistance so far!!

Nick

[BSTRobin]

Hello Nick,

Could I know  your application?

For your jumping test, it needed to record detailed test procedure according your application, capture more than one hundred steps of data(X, Y, Z axis LSB data) to analyse it.

[Nikosant03]

Hi BSTRobin,

I will use the BMX160 inside the insole of a shoe. When steps are detected (meaning that the user has wear the shoe) then the interrupt signal will wake up the MCU from its Low Power state. This is the reason I want to filter out the jumps as well as events that are not related with steps, because I do not want the MCU to wake up from events irrelavant with steps.

Do you have any code, that is capable of detecting steps with higher accuracy?

Nick

[BSTRobin]

Hello Nick,

To prevent false triggering, BMI160 step counter has a buffer mechanism. For example, if 6 steps was buffered, step counter value will be read out with the 7th step.