topic I2C on MKL15 in Kinetis Microcontrollers

I2C on MKL15

serjnone — Tue, 02 Sep 2014 12:36:00 GMT

Hi.

I have some problems witch i2c on mkl15z128.

I try to communicate with RTC DS1338. For beginning i try get on the bug START condition, Slave address write and STOP condition.

But i have problems.

I use PTE0/TPE1 GPIO pins.

My init function

void init_I2C(void)

{

SIM_SCGC4 |= SIM_SCGC4_I2C1_MASK; //Turn on clock to I2C1 module

SIM_SCGC5 |= SIM_SCGC5_PORTE_MASK;

/* configure GPIO for I2C1 function */

PORTE_PCR0 = PORT_PCR_ISF_MASK | PORT_PCR_MUX(6);

PORTE_PCR1 = PORT_PCR_ISF_MASK | PORT_PCR_MUX(6);

I2C1_F = I2C_F_ICR(14) | I2C_F_MULT(0);

I2C1_C1 = I2C_C1_IICEN_MASK;

}

My functions for write i take from examples

void i2c_Wait(void)

{

while((I2C1_S & I2C_S_IICIF_MASK)==0)

{

wdtFeed();

}

I2C1_S |= I2C_S_IICIF_MASK;

}

void IIC_StartTransmission (unsigned char SlaveID, unsigned char Mode)

{

if(Mode == MWSR)

{

/* set transmission mode */

MasterTransmission = MWSR;

}

else

{

/* set transmission mode */

MasterTransmission = MRSW;

}

/* shift ID in right possition */

SlaveID = (unsigned char) MMA7660_I2C_ADDRESS << 1;

/* Set R/W bit at end of Slave Address */

SlaveID |= (unsigned char)MasterTransmission;

/* send start signal */

i2c_Start();

/* send ID with W/R bit */

i2c_write_byte(SlaveID);

}

void MMA7660WriteRegister(unsigned char u8RegisterAddress, unsigned char u8Data)

{

/* send data to slave */

IIC_StartTransmission(SlaveID,MWSR);

i2c_Wait();

/* Send I2C address */

I2C1_D = u8RegisterAddress;

i2c_Wait();

/* Send data */

I2C1_D = u8Data;

i2c_Wait();

i2c_Stop();

//Pause();

}

When i call MMA7660WriteRegister(0x1, 0x2) i have reboot device by WDT.

When i insert wdtFeed in while loop i have no reboot.

while((I2C1_S & I2C_S_IICIF_MASK)==0)

{

wdtFeed();

}

I have START condition but in I2C1_S i have no I2C_S_IICIF_MASK after START.

I have no idea what i do wrong. Pleas help me.

Re: I2C on MKL15

Jorge_Gonzalez — Tue, 02 Sep 2014 21:59:41 GMT

Hello serj none:

I assume you have pullup resistors in SCL and SDA lines, correct?

I would recommend checking the bus with an oscilloscope or logic analyzer. The IICIF flag should set as soon as 9 clock cycles are shifted out (8-bit data + ack/nack). The flag should set disregarding if the slave responds or not.

And some observations about your code:

- You are using I2C1 (not I2C0). Just double check that i2c_start(), i2c_write_byte() and i2c_Stop() functions refer to this I2C module instance.

- For address cycle the bit I2C1_C1[TX] should be set to '1', indicating Transmit mode. I do not see this in your code.

- Your function IIC_StartTransmission receives SlaveID as parameter, but then completely ignores such value and overwrites it with MMA7660_I2C_ADDRESS. Verify that you use the correct address for your RTC slave device.

I hope these comments help.

Regards!,
Jorge Gonzalez

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Re: Re: I2C on MKL15

serjnone — Thu, 04 Sep 2014 17:44:06 GMT

Thank you.

There are was shoted SCL and SCK lines.

I use i2c_1 and all fanctions referred to i2c_1.

I think examples from IAR not fully corrected.

After simple code i2s_start() in my project dos not work - a wrong slave address transmitted.

But if i write

i2c_start();

while((I2C1_S & (1<<5)) == 0); //waite while BUSY bit set

in any cases transmit correct slave address.

Also I change i2c_stop() :

i2c_stop();

while((I2C1_S & (1<<5)) != 0); //waite while BUSY bit clear

Now my code work stable and relable.

Thank you fo help.