I2C_MasterReadBuf and related

[FrGi_297391]

I am trying to understand more about I2C and the use of it in PSoC.

   

At this moment i am working with a MPU-6050. There is a library for this component and it works all fine. 

   

But..... its to easy for me to just use a library, copy/past it and ready. 

   

At the moment i have code that works with the I2C_MasterReadByte() function. 

   

Is there a way to use the I2C_MasterReadBuf() function?

   

And is there a way to shorten this piece of code?

   

Best Regards,

   

Frank

[Bob_Marlowe]

You need to use I2C_MasterWriteBuf() at first 

   

The high-level APIs must be used in this way:

   

Writing to slave Count bytes
I2C_MasterWriteBuf(SlaveAddress,DataPtr,Count,I2C_MODE_COMPLETE_XFER);

   

Reading from Slave sending register/command byte first:
I2C_MasterWriteBuf(SlaveAddress,&RegAddress,1,I2C_MODE_NO_STOP);
I2C_MasterReadBuf(SlaveAddress,DataPtr,Count,I2C_MODE_REPEAT_START);

   

Bob

[FrGi_297391]

        Thanks for the response, despite it still doesn't work. I made the code like below. Where wBuf is an array: uint8 wBuf[1] and wBuf[0] = 0x3B Where rBuf is an array: uint8 rBuf[14] Where status is uint8 I2C_MasterWriteBuf(0x68,wBuf,1,I2C_MODE_NO_STOP); I2C_MasterClearStatus(); I2C_MasterReadBuf(0x68,rBuf,14,I2C_MODE_REPEAT_START); status=I2C_MasterStatus(); When i debug the program i will find status = 4 (I2C_MSTAT_XFER_INP) transfer in progress But de rBuf array isn't filled with any value.   

[Bob_Marlowe]

Try to remove the line I2C_MasterClearStatus();

   

Ensure that global interrupts are enabled

       

Bob

[FrGi_297391]

        Hi Bob, I tryed with removed I2C_MasterClearStatus() but it didn't work either. The global interrupts are enabled. De code below works, its with I2C_masterSendStart(), I2C_MasterWriteByte(), I2C_MasterSendRestart(), I2C_MasterReadByte() and I2C_MasterSendStop(). So the I2C setup works and have data in my rBuf array. Its now just that i want to understand how to use the read and write with API I2C_MasterReadBuf() and I2C_MasterWriteBuf() //Read data from MPU-6050 uint8_t i=0; I2C_MasterSendStart(0x68, I2C_WRITE_XFER_MODE); I2C_MasterWriteByte(0x3B); //Default 0x3B I2C_MasterSendRestart(0x68, I2C_READ_XFER_MODE); while (i++ < (14-1)) { rBuf[i-1] = I2C_MasterReadByte(I2C_ACK_DATA); } rBuf[13] = I2C_MasterReadByte(I2C_NAK_DATA); I2C_MasterSendStop();   

[Bob_Marlowe]

My I2C interface works (usually). 😉

   

Can you upload your complete project so that we all can have a look at all of your settings. To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file.

       

Bob

[FrGi_297391]

Hi Bob,

   

So after reading some stuff on the internet i found out that the I2C uses its own interrupt. I use some interrupts myself in the application. It looks like the I2C component does'nt like that at all. Yep and after checking the interrupts priority i found out they where all on the same(1).  I changed that in the right one for the I2C_I2C_IRQ to priority (0). And the other onces in order from priority, its logical.

   

Despite it did'nt work direct. I also had to add I2C_MasterClearWriteBuf() and I2C_MasterClearReadBuf(). After that it worked all perfectly.

   

So to use the I2C_MasterWriteBuf() and I2C_MasterReadBuf() you have to do it in following order.

   

Look after your priority from the interrupt when you use other interrupts in your application.

   

And than code like:

   

wBuf[1];

   

rBuf[14]; //Number of bytes you want to read

   

wBuf[0] = cmdAdress;

   

I2C_MasterClearWriteBuf();
    I2C_MasterWriteBuf(devAdress,wBuf,1,I2C_MODE_NO_STOP);
    while (0u == (I2C_MasterStatus() & I2C_MSTAT_WR_CMPLT)) //Waits until master completes write transfer 
           
    if (0u == (I2C_MSTAT_ERR_XFER & I2C_MasterStatus())) //Check transfer status 
    {
        if(I2C_MasterGetWriteBufSize() == 1) //Check if all bytes was written 
        {
            //What ever you want to do after writing the byte
        }
    }
    else
    {
        //What ever you want to do when something wrong
    }
        
    I2C_MasterClearReadBuf();
    I2C_MasterReadBuf(devAdress,rBuf,14,I2C_MODE_REPEAT_START);
    while (0u == (I2C_MasterStatus() & I2C_MSTAT_RD_CMPLT)) //Waits until master complete read transfer 
    
    if (0u == (I2C_MSTAT_ERR_XFER & I2C_MasterStatus())) //Displays transfer status 
    {
        if(I2C_MasterGetReadBufSize() == 14) // Check if all bytes was written 
        {
            //What ever you want to do after reading all the bytes
         }
    }
    else
    {
        //What ever you want to do when something wrong
    }

   

Thanks Bob for the hints.

   

Happy coding,

   

Frank