topic Re: Accelerometer interruption MMA8652FC don't work in Sensors

Accelerometer interruption MMA8652FC don't work

hugooliveira — Tue, 03 Feb 2026 21:04:22 GMT

Hi,

I did MMA8652FC accelerometer configuration to detect motion. However, the interrupt pin does not work, and the recorder is in EA bit FF_MT_SRC 1 and SRC_FF_MT bit is also in 1.

I configured so that the interruption is active in the INT1 pin.

Follows the configuration

Registrador	Valor
XYZ_DATA_CFG	0x00
CTRL_REG1	(DR=101)
FF_MT_CFG	0xF8
FF_MT_THS	0x20
FF_MT_COUNT	0x02
CTRL_REG3	0xF9
CTRL_REG4	0xFF
CTRL_REG5	0xFF

Re: Accelerometer interruption MMA8652FC don't work

TomasVaverka — Mon, 02 Nov 2020 13:26:24 GMT

Hi Hugo,

To clear the SRC_FF_MT interrupt status bit in the INT_SOURCE register (0x0C) and consequently deassert the Freefall/Motion interrupt, it is necessary to read the FF_MT_SRC register. Are you using something like this?

void PORTA_IRQHandler()
{
      PORTA_PCR5 |= PORT_PCR_ISF_MASK; // Clear the interrupt flag 
      Temp = I2C_ReadRegister(MMA8652FC_I2C_ADDRESS, FF_MT_SRC_REG); // Read the FF_MT_SRC register to clear the SRC_FF_MT flag in the INT_SOURCE register and deassert the interrupt    
      MotionEventCounter++;
}

Also make sure that your GPIO pin connected to the INT1 pin of the MMA8652FC is configured for falling edge interrupts.

I would also recommend to start your experimenting without using the Auto Wake/Sleep function (CTRL_REG3 = 0x00), with only the Motion/Freefall interrupt enabled (CTRL_REG4 = 0x04) and routed to the INT1 pin (CTRL_REG5 = 0x04).

I hope it helps.

Regards,

Tomas

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

Re: Accelerometer interruption MMA8652FC don't work

hugooliveira — Thu, 17 Mar 2016 14:57:25 GMT

Hi Tomas,

I made all of these settings, but unfortunately the interruption does not work ... you would have a complete sample configuration that was already made and it worked?

Thank you.

Re: Accelerometer interruption MMA8652FC don't work

TomasVaverka — Fri, 18 Mar 2016 09:09:26 GMT

Hi Hugo,

Attached you can find a simple code example for motion detection based on the AN4070.

I hope it helps.

Regards,

Tomas

Re: Accelerometer interruption MMA8652FC don't work

hugooliveira — Tue, 22 Mar 2016 19:33:23 GMT

Hi Tomas,

Thanks for your help. The problem was being in uC interrupt setting. The interruption did not work when placed in open drain and not in pushpull only worked when the pin configured as pullup. The uC that use is PROC of Cypress.