MMA8452Q int1

Development Boards Arduino
1

I am getting a high on int all the time even when there are no changes. I am using the advanced example. Has anyone else this problem? Is this normal? Can i change a register to get it to only trip int1 when there is motion?

2

I never used this chip but am look through the data sheet on INT1 usage. Here are the relevant sections to read:

5.9

Table 11, CNT_REG5

Table 61 & 62

Other than these the DS a rather vague on how the INT1 & 2 pins work.

Dig and read carefully. There may be something needed to be written to to clear an existing INT (clear interrupt Flag in processors idea).

3

My guess from looking at the source code and Table 14 in the datasheet is that the interrupt is signalling that new data is available.

From the DS, Table 14: Bit 0 (SRC_DRDY)

Data Ready Interrupt bit status. Default value: 0.
Logic ‘1’ indicates that the X, Y, Z data ready interrupt is active indicating the presence of new data and/or data overrun. Otherwise if it is a logic ‘0’ the X, Y, Z interrupt is not active.
This bit is asserted when the ZYXOW and/or ZYXDR is set and the interrupt has been enabled.
This bit is cleared by reading the X, Y, and Z data.

From the sketch :

void loop()
{  
  static byte source;
  
  /* If int1 goes high, all data registers have new data */
  if (digitalRead(int1Pin))  // Interrupt pin, should probably attach to interrupt function
  //if (readRegister(0x00)&0x7) // Polling, you can use this instead of the interrupt pins
  {
    readRegisters(0x01, 6, &data[0]);  // Read the six data registers into data array