comunication between color sensor and stm8s-discovery with i2c

[daniela1988]

Posted on February 01, 2011 at 16:09

Hi!

I want that stm8s-discovery read color  using a color sensor (

ADJD-S371-QR999).

I use i2c protocol in this way:

I2C_GenerateSTART(ENABLE);

    while(!I2C_CheckEvent(I2C_EVENT_MASTER_START_SENT));</span></div>

     // i want to read data from color sensor (0x74)

  I2C_Send7bitAddress(0x74, I2C_DIRECTION_RX);

while(!I2C_CheckEvent(I2C_EVENT_MASTER_ADDRESS_ACKED));

I2C_ClearFlag(I2C_FLAG_ADDRESSSENTMATCHED);

while (Rx_Idx < RX_BUFFERSIZE)

{

while(!I2C_CheckEvent(I2C_EVENT_MASTER_BYTE_RECEIVED));

I2C_Buffer_Rx[Rx_Idx++] = I2C_ReceiveData();

}

//nack.... in this point, master have to send a NACK to sensor in order to finish the i2c protocol.

I2C_ClearITPendingBit(I2C_ITPENDINGBIT_ACKNOWLEDGEFAILURE); </span></div>

 I2C_GenerateSTOP(ENABLE);

I don't Know if this is the correct method to send NACK and moreover i not sure that the implementation of protocol is right.

I need help, please!

Thank you!

[brazov22]

Posted on February 02, 2011 at 08:55

Hi Danielina,

try in this way, it'd work:

 /* Phase of I²C transmission */

 /* Generate START condition and test on EV5 and clear it */

 I2C_GenerateSTART(ENABLE);

  while(!I2C_CheckEvent(I2C_EVENT_MASTER_START_SENT));

 /* Send slave 7 bits adress and test on EV6 and clear it */

 I2C_Send7bitAddress(0x74, I2C_DIRECTION_RX);

  while(!I2C_CheckEvent(I2C_EVENT_MASTER_ADDRESS_ACKED));

 I2C_ClearFlag(I2C_FLAG_ADDRESSSENTMATCHED);

 /* Wait RXNE=1 EV7 bit is setI2C_Buffer_RX is ready to read */

while (Rx_Idx < RX_BUFFERSIZE)

{

while(!I2C_CheckEvent(I2C_EVENT_MASTER_BYTE_RECEIVED));

I2C_Buffer_Rx[Rx_Idx++] = I2C_ReceiveData();

}

/* Generate STOP condition and leave the serial bus free */

I2C_GenerateSTOP(ENABLE);

protocol seems ok, I think you can close comunication generating a STOP.

brazov