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

[Nikosant03]

Hi BSTRobin,

Thank you for your suggestion, indeed the buffer mechanism could be usefull. Can I interact with the buffer mechanism through the API? If yes, how this is possible?

Thanks

Nick

[BSTRobin · Accepted solution]

Hello Nikosant03,

Buffer mechanism was running in internal algorithm, the following bits with red line could be set to change the buffer size.

[Nikosant03]

Hi BSTRobin,

Thanks I will give a try!! That means that according to the datasheet (pg89 )in Normal mode the buffer size is 3, in Sensitive mode is 0 and in Robust mode is 7

To be sure that I have understand it correctly, in Normal (buffer size 3) an interrupt will be generated every 4 steps while in Robust mode every 8 steps?

[BSTRobin · Accepted solution]

Hello Nikosant03,

Depending on internal algorithm, if min_step_buf is set to 3, 6 steps will be buffered, with the 7th step, step counter allows output.

If if min_step_buf was set as a value, it should be added 3 for step counter buffer.