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