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MMA8451Q Accelerometer for Harsh Breaking Application

Question asked by Pawan Das on Mar 9, 2017


   We are trying to use MMA8451Q for 'Harsh breaking application' with the help of Embedded Transient function present in the accelerometer. But have following issues/questions: 

  1. Choosing High pass filter cutoff value is one of the critical parameter that needs to be taken care. We thought of considering data rate of 100 Hz and High Pass filter cutoff of 0.5 Hz. But not absolutely sure whether this will help for the kind of problem that we are targeting?
  2. If High pass Filter is used, will it affect the time required to Fill the FIFO?
  3. I also want to use the raw data coming from x, y, z axes for some other application. Is there a way where I can avoid it passing through High Pass Filter?


Following is the Approach:




   I2C_Write(XYZ_DATA_CFG, 0x10);

   I2C_Write(HP_FILTER_CUTOFF, Cutoff_Val);

   I2C_Write(CTRL_REG1, DataRate);

   I2C_Write(TRANSIENT_CFG, Transient_Cfg_Val);

   I2C_Write(TRANSIENT_THS, Transient_Threshold_Val);

   I2C_Write(TRANSIENT_COUNT, Debounce_count_Val);




Any help is greatly appreciated. Thanks in advance.