MMA8451Q Interrupt based reading of accelerometer using FRDM-KL25Z

[Raghahanuma]

I'm getting a fault at these lines, I don't know what is wrong with it. have I coded the interrupt part wrong ?

NVIC_EnableIRQ(PORTA_IRQn);

NVIC_SetPendingIRQ(PORTA_IRQn);

Below is my complete code,

#include <stdio.h>

#include "board.h"

#include "peripherals.h"

#include "pin_mux.h"

#include "clock_config.h"

#include "MKL25Z4.h"

#include "fsl_debug_console.h"

#include "pin_mux.h"

#include "fsl_gpio.h"

#include "fsl_port.h"

/* TODO: insert other include files here. */

/* TODO: insert other definitions and declarations here. */

#define MMA8451_SA 0x1D

/* MMA8451 Registers */

#define MMA8451_REG_WHOAMI 0x0D

/*

* u/brief Application entry point.

*/

int main(void) {

/* Enable clock for PORTE */

SIM->SCGC5 = (1 << SIM_SCGC5_PORTE_SHIFT);

/* Enable clock for I2C0 */

SIM->SCGC4 = (1 << SIM_SCGC4_I2C0_SHIFT);

BOARD_I2C_ReleaseBus();

/* PORTE24 pin as I2C0_SCL */

PORTE->PCR[24] = (5 << PORT_PCR_MUX_SHIFT) | (1 << PORT_PCR_PS_SHIFT) | (1<<PORT_PCR_PE_SHIFT) | (1<<PORT_PCR_SRE_SHIFT);

/* PORTE25 pin as I2C0_SDA */

PORTE->PCR[25] = (5 << PORT_PCR_MUX_SHIFT) | (1 << PORT_PCR_PS_SHIFT) | (1<<PORT_PCR_PE_SHIFT) | (1<<PORT_PCR_SRE_SHIFT);

/* clear interrupt flag and set pins of port A as gpio*/

PORTA->PCR[14]= (0 | PORT_PCR_ISF_MASK) | (1 << PORT_PCR_MUX_SHIFT) | PORT_PCR_IRQC(0xA);

//NVIC_REG->iser[0] = (1 << 16);

// NVIC_REG->icpr[0] = (1 << 16);

NVIC_EnableIRQ(PORTA_IRQn);

NVIC_SetPendingIRQ(PORTA_IRQn);

/* I2C0 Frequency Divider */

I2C0->F = 0x0F;

/* I2C0 Enable, Master Mode */

I2C0->C1 = (1 << I2C_C1_IICEN_SHIFT) | (1 << I2C_C1_IICIE_SHIFT);

I2C0->S |= (1 << I2C_S_IICIF_SHIFT);

/* I2C0 Check for Bus Busy */

while(I2C0->S & (1 << I2C_S_BUSY_SHIFT));

data = i2c_read(MMA8451_SA, MMA8451_REG_WHOAMI);

while(I2C0->S & (1 << I2C_S_BUSY_SHIFT));

data = i2c_read(MMA8451_SA, MMA8451_REG_WHOAMI);

data = i2c_read(MMA8451_SA, MMA8451_REG_WHOAMI);

i2c_write(MMA8451_SA, 0x2A, 0x01);

data = i2c_read(MMA8451_SA, 0x2A);

i2c_write(MMA8451_SA, CTRL_REG4, 0x01); // Enable DRDY interrupt

i2c_write(MMA8451_SA, CTRL_REG5, 0x01); // DRDY interrupt routed to INT1

while(1) {

//if(dataready){

//dataready=0;

/* X Offset LSB */

}

return 0;

}

void PORTA_IRQHandler()

{

//PORTA->PCR[14]=(0<< PORT_PCR_ISF_SHIFT); // Clear the interrupt flag

//dataready = 1;

/* X Offset LSB */

data = i2c_read(MMA8451_SA, 0x02);

xoff = data;

/* X Offset MSB */

data = i2c_read(MMA8451_SA, 0x03);

xoff |= (data << 8);

/* Y Offset LSB */

data = i2c_read(MMA8451_SA, 0x04);

yoff = data;

/* Y Offset MSB */

data = i2c_read(MMA8451_SA, 0x05);

yoff |= (data << 8);

/* Z Offset LSB */

data = i2c_read(MMA8451_SA, 0x06);

zoff = data;

/* Z Offset MSB */

data = i2c_read(MMA8451_SA, 0x07);

zoff |= (data << 8);

printf("XOFF: 0x%04x YOFF: 0x%04x ZOFF: 0x%04x\n", xoff, yoff, zoff);

PORT_ClearPinsInterruptFlags(PORTA, (1 << 12));

}

[JackITB]

Hi Raghahanuma,

Be aware that control registers settings are updated only if the sensor is in standby mode.

So I suggest you change your sequence as per below:

i2c_write(MMA8451_SA, 0x2A, 0x00); // Put sensor in Standby mode (this will be already the case after POR or Reset)

i2c_write(MMA8451_SA, CTRL_REG4, 0x01); // Enable DRDY interrupt

i2c_write(MMA8451_SA, CTRL_REG5, 0x01); // DRDY interrupt routed to INT1

i2c_write(MMA8451_SA, 0x2A, 0x01);

data = i2c_read(MMA8451_SA, 0x2A); // optional verification

Hope this will help.

[bobpaddock]

NVIC_SetPendingIRQ(PORTA_IRQn);

After the clock issue is addressed,
why is that being used?

That will force the PORTA IRQ to fire and I2C is not yet configured.

The Accel itself will generate an IRQ when it is ready, after everything is correctly configured.

[Raghahanuma]

Tried everything still not getting the output!

[Robin_Shen]

No output from INT1 or I2C?

[Raghahanuma]

NVM! The problem was that I didn't route the interrupt back to port A 14 so it didn't throw up any output now its working fine. thanks for your contribution. 

[Robin_Shen · Accepted solution]

Hi Raghahanuma,

This fault is not caused by NVIC_EnableIRQ(PORTA_IRQn);,

This is because the clock gate for PORTA is not enabled, but you accessed PORTA->PCR[14].

Please enable the clock gate of PORTA.

Best Regards,
Robin
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[Raghahanuma]

Thanks well that solved the fault but still not getting the output. will work on it and update