I have some problem about MMA8652's low power

[ipx002]

Hi

    I have some problem about MMA8652 . I set the ODR=1.56(CTRL_REG1=0x38) , and work in low power mode(CTRL_REG2=0x1b) . It's current should be 6.5 uA.

   

   But I read the current is 170 uA with digital ammeter . Why?

And my Schematic like that

my code is

IIC_write(CTRL_REG1,0x38);              //ODR = 1.56Hz, standby

IIC_write(XYZ_DATA_CFG_REG,0x02);       //+/-8g

IIC_write(CTRL_REG2,0x1b);              //Low Power

  IIC_write(PULSE_CFG_REG, 0x15);         //Enable X, Y and Z Single Pulse

  IIC_write(PULSE_THSX_REG, 0x78);        //Set X Threshold to 7.56g

  IIC_write(PULSE_THSY_REG, 0x78);        //Set Y Threshold to 7.56g

  IIC_write(PULSE_THSZ_REG, 0x78);        //Set Z Threshold to 7.56g

  IIC_write(PULSE_TMLT_REG, 0x28);        //Set Time Limit for Tap Detection to 25 ms

  IIC_write(PULSE_LTCY_REG, 0x28);        //Set Latency Time to 50 ms

  IIC_write(CTRL_REG4, 0x08);             //Pulse detection interrupt enabled

  IIC_write(CTRL_REG5, 0x08);             //Route INT1 to system interrupt

  data = IIC_read(CTRL_REG1);   //Active Mode

  data |= 0x01;

  IIC_write(CTRL_REG1, data);

Thank you ! every body!

[TomasVaverka]

Hi Jun,

How are you measuring this current consumption? Are not there other devices drawing current as well?

Also be aware that the current consumption stated in the datasheet applies for VDD=2.5V and has been measured with an amperemeter between 2.5V voltage rail and VDD input only.

Best regards,

Tomas

PS: If my answer helps to solve your question, please mark it as "Correct". Thank you.

[ipx002]

Hi Tomas

    Thank you for you reply !

     I already know the reason . Because the  MCU's IIC isn't working , so the sensor's register use default value .

     This is my fault !

     Thanks again !

     (PS: I am chineses. My family name is "Wu" , not "Jun"..haha...)