topic I2C IICIF bit flag not activated on transfer in Kinetis Microcontrollers

I2C IICIF bit flag not activated on transfer

luisluna — Sun, 14 Sep 2014 04:24:20 GMT

Hi,

Does anybody of you have happen that after reading some registers in a slave device the IICIF bit flag does not get activated after sendind the register address to the slave device?

This is happening after reading successfully a register and attempting to send the next register address with the same slave address. I think that the I2C module is properly configured because I can communicate with the accelerometer in the board, but when I try other devices I get stuck waiting to for the register address to be send.

This is my init code for the I2C

void init_I2C(void)

{

SIM_SCGC4 |= SIM_SCGC4_I2C0_MASK; // Turn on clock to I2C0 module

BW_PORT_PCRn_MUX(PORTE_BASE,24u,kPortMuxAlt5); // Configure pin functionality for I2C0

BW_PORT_PCRn_MUX(PORTE_BASE,25u,kPortMuxAlt5);

I2C0_F = 0x17; // SLC divider is 128 for 50MHz clock (I2C works in ~390KHz).

I2C0_C1 = I2C_C1_IICEN_MASK; // enable IIC

}

This is how I read the registers:

unsigned char ReadRegister(unsigned char u8RegisterAddress)

{

unsigned char result;

/* Send Slave Address */

IIC_StartTransmission(SlaveID,MWSR);

i2c_Wait();

/* Write Register Address */

I2C0_D = u8RegisterAddress;

i2c_Wait();

/* Do a repeated start */

I2C0_C1 |= I2C_C1_RSTA_MASK;

/* Send Slave Address */

I2C0_D = (OV7740_I2C_ADDRESS << 1) | 0x01; //read address

i2c_Wait();

/* Put in Rx Mode */

I2C0_C1 &= (~I2C_C1_TX_MASK);

/* Turn off ACK since this is second to last byte being read*/

I2C0_C1 |= I2C_C1_TXAK_MASK;

/* Dummy read */

result = I2C0_D ;

i2c_Wait();

/* Send stop since about to read last byte */

i2c_Stop();

/* Read byte */

result = I2C0_D ;

return result;

}

#define i2c_Start() I2C0_C1 |= I2C_C1_TX_MASK;\

I2C0_C1 |= I2C_C1_MST_MASK

#define i2c_Stop() I2C0_C1 &= ~I2C_C1_MST_MASK;\

I2C0_C1 &= ~I2C_C1_TX_MASK

This is how I wait fo the byte to be transmited and were my code get stuck because the IICIF bit never gets active.

#define i2c_wait() while((I2C0_S & I2C_S_IICIF_MASK)==0) {} \

I2C0_S |= I2C_S_IICIF_MASK;

Re: I2C IICIF bit flag not activated on transfer

mjbcswitzerland — Sun, 14 Sep 2014 20:41:22 GMT

Luis

Are you sure that the first I2C message transmission has completed (stop condition completed) before sending a second message to a different device?

Try waiting for the bus to become idle before sending the second message - eg.

while (I2C0_S & IIC_IBB) {}

Regards

Mark

Re: I2C IICIF bit flag not activated on transfer

luisluna — Tue, 16 Sep 2014 20:13:05 GMT

Thanks Mark,

Seems like this was causing the issue.

Re: I2C IICIF bit flag not activated on transfer

jonathanlee — Mon, 01 Dec 2014 01:44:38 GMT

Hi,Luis,

I have the same question as yours, would you please tell me where you put this "while (I2C0_S & IIC_IBB) {}" to solve the problem?

Best Regards!

Re: I2C IICIF bit flag not activated on transfer

luisluna — Mon, 01 Dec 2014 18:55:07 GMT

Hi Li,

It was needed to be added after the read of the data, like:

unsigned char ReadRegister(unsigned char u8RegisterAddress)

{

unsigned char result;

/* Send Slave Address */

IIC_StartTransmission(SlaveID,MWSR);

i2c_Wait();

/* Write Register Address */

I2C0_D = u8RegisterAddress;

i2c_Wait();

/* Do a repeated start */

I2C0_C1 |= I2C_C1_RSTA_MASK;

/* Send Slave Address */

I2C0_D = (OV7740_I2C_ADDRESS << 1) | 0x01; //read address

i2c_Wait();

/* Put in Rx Mode */

I2C0_C1 &= (~I2C_C1_TX_MASK);

/* Turn off ACK since this is second to last byte being read*/

I2C0_C1 |= I2C_C1_TXAK_MASK;

/* Dummy read */

result = I2C0_D ;

i2c_Wait();

/* Send stop since about to read last byte */

i2c_Stop();

/* Read byte */

result = I2C0_D ;

/* Wait for the bus to be free */

while (I2C0_S & I2C_S_BUSY_MASK)

{}

return result;

}

where I2C_S_BUSY_MASK is 0x20u

Hope this helps :smileysilly:

Re: I2C IICIF bit flag not activated on transfer

jonathanlee — Tue, 02 Dec 2014 00:59:11 GMT

Hi,Luis,

Thanks for your reply.

It helps,my program works well now. I add while (I2C0_S & I2C_S_BUSY_MASK), and send nack.

Thanks again.

Best Regards!