I2C not working

[akex]

Posted on December 09, 2010 at 18:11

I2C not working

[akex]

Posted on May 17, 2011 at 14:17

WEll, now the I2C is in operational mode, but still not working quite right.

The clock line doesnt seem to generate a clock

for starters, im trying to send a start signal, then the adress, then repeated start, then adrress again, etc.

this is what im getting on the scope, and my code:

 

the code:

GPIOB_CRH = 0x0000DD00;//I2C lines are AF output open drain

   

RCC_APB1ENR = 0x00400000; //enable I2C2 clock

RCC_APB2ENR = 0x0000000D; //enable PA,PB,AF clock

   

I2C2_OAR1 = 0x00004000; //bit 14 should be kept 1 by software

I2C2_CR2 = 0x00000008; //frequency 36 mHZ, //enable event interrupts  

I2C2_CCR = 0x00000028; //clock configure

I2C2_TRISE) = 0x00000009; // Rise time

I2C2_CR1 = 0x00000401; //Enable ACK, Enable I2C

 

while (1)

{

    I2C2_CR1 |=0x00000100; //send START

         

          while(I2C2_SR1<1); //wait till START is complete

          delay(1);

         

          *(uint32*)(I2C2_DR) = 0b10010010;

          //while( (I2C2_SR1 >>1) <1);   <- wait till address has been sent. If I use that line, the code gets stuck, meaning this condition isnt fulfilled

          delay(10);  

      }

thanks again!

[nanayakkaraan]

Posted on May 17, 2011 at 14:17

Hello alex,

I would point out the steps I needed to follow in order to make I2C work.

• Enable the GPIO port in which I2C_SDA and I2C_SDL pins are in.
• Enable peripheral clock on the particular GPIO port.
• Configure AFIO (alternative functions) so that the pins will be working as  I2C_SDA and I2C_SDL.
• Enable peripheral clock for I2C.
• The remaining configurations (which you have mentioned in the post) were done after this.

Hope this might help you. :)

[greg_t]

Posted on May 17, 2011 at 14:17

You should enable the clock

[akex]

Posted on May 17, 2011 at 14:18

These are the right pins, and both have pull up resistors.

I really need to build this on my own, and not use libraries for the purposes of my project.

Any other solutions & suggestions will be appreciated!

[Tesla DeLorean]

Posted on May 17, 2011 at 14:18

WEll, now the I2C is in operational mode, but still not working quite right. The clock line doesnt seem to generate a clock

Check you have the right pins, and there is a pull up on the clock pin.

Better yet, use the library and example code.

[Tesla DeLorean]

Posted on May 17, 2011 at 14:18

I really need to build this on my own....

How fantastically ironic.

Ok, what is your clock rate for the APB1? I'd guess from the settings 8 MHz, but your comments suggest 36 MHz, so which is it?

[gbulmer]

Posted on May 17, 2011 at 14:18

Are you allowed to use library code and examples to test the hardware?

If you can isolate the probem to either hardware, or software, progress may be easier and quicker.

[akex]

Posted on May 17, 2011 at 14:18

I really need to build this on my own....

 

 

How fantastically ironic.

 

 

hehe, by ''on my own'' I meant ''manually'', not alone, in the dark, without internet :)

As for the clock rate, its 8 MHz, the comments for the I2C2_xxx registers are wrong for some reason.

I took all the clock settings from the reference manual, it has an exapmle for setting the right clock rates for 100 kHz speed