FXOS8700CQ Motion Detection and Interrupts

[alejandrovelez]

Greetings,

I'm trying to configure the FXOS8700CQ sensor with motion detection and interrupt in one of the two interrupt pins. So far I tried to do an example from the application note AN4070 made for a MMA8451 Sensor changing the register number for the FXOS8700CQ ones, but I still don't get the interrupt.

I follow the steps:

Example Steps for Configuring Motion Detection

X or Y > 3g using MFF Function 4g, 100 Hz ODR, Normal Mode

Step 1: Put the device into Standby Mode: Register 0x2A CTRL_REG1

IIC_RegWrite(0x2A, 0x18); //Set the device in 100 Hz ODR, Standby

Step 2: Set Configuration Register for Motion Detection by setting the “OR” condition OAE = 1, enabling

X, Y, and the latch

IIC_RegWrite(0x15, 0xD8)

Step 3: Threshold Setting Value for the Motion detection of > 3g //(I tried with less Threshold)

Note: The step count is 0.063g/ count

• 3g/0.063g = 47.6; //Round up to 48

IIC_RegWrite(0x17, 0x30)

Step 4: Set the debounce counter to eliminate false readings for 100 Hz sample rate with a requirement

of 100 ms timer.

Note: 100 ms/10 ms (steps) = 10 counts

IIC_RegWrite(0x18, 0x0A);

Step 5: Enable Motion/Freefall Interrupt Function in the System (CTRL_REG4)

IIC_RegWrite(0x2D, 0x04);

Step 6: Route the Motion/Freefall Interrupt Function to INT1 hardware pin (CTRL_REG5) //(I tried with int1 and int2)

IIC_RegWrite(0x2E, 0x04);

Step 7: Put the device in Active Mode

CTRL_REG1_Data = IIC_RegRead(0x2A);

CTRL_REG1_Data| = 0x01;

IIC_RegWrite(CTRL_REG1_Data);

Step 8: Write Interrupt Service Routine Reading the System Interrupt Status and the Motion/Freefall

Status

I did exactly, but with the correct register numbers for the FXOS8700CQ sensor.

I'm using a FRDM-K64F with its embedded accelerometer and Processor Expert for the I2C communication. The pins are correctly configured and the I2C communication works good but I don't get an interrupt when I move it.

Is there something that I'm missing?

Thanks for the help!

[anthonyduhamel]

Hi Alejandro,

For motion detection, I advise you to use the Acceleration Vector-Magnetitude detection feature inluded in the FXOS8700CQ device.

Here a code sample for integration :

////////////////////////////////////////////////////////////////////////////////
//!                                Defines
////////////////////////////////////////////////////////////////////////////////
// Cfg register
#define FXOS8700_WHO_AM_I 0x0D
#define FXOS8700_CTRL_REG1 0x2A
#define FXOS8700_CTRL_REG2 0x2B
#define FXOS8700_CTRL_REG3 0x2C
#define FXOS8700_CTRL_REG4 0x2D
#define FXOS8700_CTRL_REG5 0x2E
#define FXOS8700_M_CTRL_REG1 0x5B
#define FXOS8700_M_CTRL_REG2 0x5C
#define FXOS8700_M_CTRL_REG3 0x5D
#define FXOS8700_XYZ_DATA_CFG 0x0E
// Interupts
#define FXOS8700_A_VECM_CFG        0x5F
#define FXOS8700_A_VECM_THS_MSB    0x60
#define FXOS8700_A_VECM_THS_LSB    0x61
#define FXOS8700_ASLP_COUNT 0x29
#define FXOS8700_TRIG_CFG 0x0A
// Data register
#define FXOS8700_M_OUT_X 0x33
#define FXOS8700_OUT_X 0x01
#define FXOS8700_TEMP 0x51
#define FXOS8700_WHO_AM_I_VALUE 0xC7
////////////////////////////////////////////////////////////////////////////////
//!                                 Static members
////////////////////////////////////////////////////////////////////////////////
static bool _b_IsFXOS8700Init=FALSE;
////////////////////////////////////////////////////////////////////////////////
//!                                 Public functions
////////////////////////////////////////////////////////////////////////////////
bool bFXOS8700_Init()
{
  bool __b_result = FALSE;
  uint8_t __u8_CmdResult = 0;
  if(!_b_IsFXOS8700Init)
  {
  I2C_Init (NULL);
  if(_bFXOS8700_Write(FXOS8700_CTRL_REG1,0x00)) // Pass to standby mode for writable operations
  if(_bFXOS8700_Read(FXOS8700_WHO_AM_I,&__u8_CmdResult)) // Check device communication
  if(__u8_CmdResult== FXOS8700_WHO_AM_I_VALUE) // Check device ID
  if(_bFXOS8700_Write(FXOS8700_XYZ_DATA_CFG,0x02)) //±0.976 mg/LSB
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG1,0x17))// Hybrid
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG2,0x00))
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG3,0x80))
  /* Sleep mode */
  if( _bFXOS8700_Write(FXOS8700_TRIG_CFG, 0x02))
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG2,0x04))//Autosleep on
  if( _bFXOS8700_Write(FXOS8700_ASLP_COUNT,0x06))//Auto-sleep trigg
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG4,0x02))//Autosleep IT enable
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG5,0x02))//IT on IT1 pin
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG3,0x07))//wake on vecm 1101
  if( _bFXOS8700_Write(FXOS8700_A_VECM_CFG,0x48))//A_VECM_CFG 
  if( _bFXOS8700_Write(FXOS8700_A_VECM_THS_MSB,0x00))//A_VECM_THS_MSB  
  if( _bFXOS8700_Write(FXOS8700_A_VECM_THS_LSB,/0x40))//A_VECM_THS_LSB 
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG3,0x04))//wake on vecm
  //---------------
  if(_bFXOS8700_Write(FXOS8700_CTRL_REG1,0x29)) // Active Mode + ODR max ->freq min
  if(_bFXOS8700_Read(0x0B,&__u8_CmdResult)) // Check WakeMode
  if((__u8_CmdResult&0x03)== 1) // ok
  {
  _b_IsFXOS8700Init = TRUE;
  __b_result  =TRUE;
  }
  }
    return __b_result;
}

Anthony

[alejandrovelez]

Hi Anthony

Thanks for the help

I have tried several codes, even yours.... my problem now is that I don't get a interrupt from the pins int1 or int2. When I poll the INT_SOURCE register  I can see that the respective interrupt bits are set and then I clear it by reading the interrupt source in the respective register. The code works with polling but I need and edge, rising or falling in the intx pin when the respective bit is asserted in the INT_SOURCE register because I need to work a processor in low power mode and then wake up it with an edge.

BR

[anthonyduhamel · Accepted solution]

Alejandro,

I've just tested again my code, (I did  some updates), it works well.

In my FXOS8700.c file:

////////////////////////////////////////////////////////////////////////////////
//!                                Public functions
////////////////////////////////////////////////////////////////////////////////
bool bFXOS8700_Init()
{
  bool __b_result = FALSE;
  uint8_t __u8_CmdResult = 0;
  if(!_b_IsFXOS8700Init)
  {
  I2C_Init (NULL);
  if(_bFXOS8700_Write(FXOS8700_CTRL_REG1,0x00)) // Pass to standby mode for writable operations
  if(_bFXOS8700_Read(FXOS8700_WHO_AM_I,&__u8_CmdResult)) // Check device communication
  if(__u8_CmdResult== FXOS8700_WHO_AM_I_VALUE) // Check device ID
  /* Acc-cell Config */
  if(_bFXOS8700_Write(FXOS8700_XYZ_DATA_CFG,0x02)) // ±0.976 mg/LSB
  /* M-cell Config */
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG1,0x17)) // Hybrid mode (mag+acc)
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG2,0x00))
  if(_bFXOS8700_Write(FXOS8700_M_CTRL_REG3,0x80))
  /* Sleep mode + wake mode config + interrupt*/
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG2,0x04 | 0x03)) // Autosleep on |LowPower
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG3,0x04|0x00)) // wake on vecm | active low | PushPull
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG4,0x02)) // VECM INT enable in sleep mode
  if( _bFXOS8700_Write(FXOS8700_CTRL_REG5,0x02)) // INT on INT1 pin
  if( _bFXOS8700_Write(FXOS8700_ASLP_COUNT,0x06)) // Auto-sleep counter
  if( _bFXOS8700_Write(FXOS8700_TRIG_CFG, 0x00)) // FIFO not used
  /* Vector Magnitude config */
  if( _bFXOS8700_Write(FXOS8700_A_VECM_CFG,0x48)) // 0b0100 1000  current x/y/z accelerometer output data as initial reference values | vecm enable
  if( _bFXOS8700_Write(FXOS8700_A_VECM_THS_MSB,0x00)) // Threshold value MSB
  if( _bFXOS8700_Write(FXOS8700_A_VECM_THS_LSB,0x40)) // Threshold value LSB
  //---------------
  if(_bFXOS8700_Write(FXOS8700_CTRL_REG1,0x29)) // Active Mode + ODR max ->freq min
  {
    _b_IsFXOS8700Init = TRUE;
    __b_result  =TRUE;
    INT_MOTIONDECTECTION_Init(NULL);
  }
  }
    return __b_result;
}
void vFXOS8700_OnMotionDetected() // Called form Event.c
{
  bool __b_IsMotionDetected;
  uint8_t __u8_CmdResult = 0xFF;
  _bFXOS8700_Read(FXOS8700_INT_SOURCE,&__u8_CmdResult);// Read INT source to clear vecm int flag
  __b_IsMotionDetected =  ( ((__u8_CmdResult>>1)&0x01)==1); // Check if vecm has been setted by it
  if(__b_IsMotionDetected )
  {
    // Wake up the MCU
  }
}

Did you have well configured your INT component? I configure it for Falling Edge interrupt. For pin number, I'm using a FRDM-KL46Z, so it's not the rigth value, yours should be PTC6 (INT1) on FRDM-K46 QRC.

In my Event.c file

void INT_MOTIONDECTECTION_OnInterrupt(LDD_TUserData *UserDataPtr)
{
  vFXOS8700_OnMotionDetected();
}

By the end, I have checked the well working of INT with a scope:

Level is normally High. When a motion is detected, There is a falling edge: Interrup is catched by the code and cleared by vFXOS8700_OnMotionDetected() function by reading the FXOS8700 INT_SOURCE register.

I hope it will help you.

Regards,

Anthony

[alejandrovelez]

Thanks Anthony, I adjusted your code to my needs and it works.

One of the problems that I was having is that there is an error in KDS 3.0 Processor Expert. The pin FXOS8700CQ_INT1 doesn't correspond to the one that is connected to de chip (PTC6).

Regards.

[anthonyduhamel]

Great catch Alejandro.

I will inform the Processor Expert team.

Thanks!

Anthony