IIC on S08DZ60, problem setting MST-bit in IICC1 register

[ohanica]

Hello!

I do not manage to set the MST-bit in the IICC1-register of my uC.  I'm using the software example of the HCS08QRUG users guide. I adapted all registers to the DZ60. Compilation is successfull.

When trying to debug in BDM with the Multilink, avery time I write IICC1_MST = 1 the bit is not changing.

Code for initialization of IIC-module in master-mode:

  IICF = 0x40;   // Set IIC frequency,100kbit  (4MHz oscillator)   IICC1_IICEN = 1;    // Enable IIC             IICC1_IICIE = 1;    // Enable IIC interrupts    IICA = 0xC0;        // IIC Address                   I2C_STEP = IIC_READY_STATUS;     I2C_DATA[0]='A'; // test data   I2C_DATA[1]='B';  I2C_DATA[2]='C';//want to set my controller to be master, to send smth afterwards...  IICC1_MST = 1;   

 In this last line the MST-bit  is not changing.

What do I do wrong?

best,

Johannes

[ohanica]

Hello again,

I did some tests right now:

If the IICC1_IICEN-bit is enabled(=1), I can only clear the MST-bit (from 1 to 0). If IICEN is set, I cannot set the MST bit (from 0 to 1). I mean, it could be that my Bus-node switches from master to slave if some other master begins to sent out smth. It should be possible to set the "own"  IIC-bus-node to master and slave as necessary... it seems to me, that is is not
don't understand that.

Now following the chapter 11.7 of the datasheet (preliminary version 06/2007) the order of initializing the IIC is the following:
1. IICF set baud rate
2. IICC1 enable IIC and interrupts
3. Initialize RAM variables (IICEN=1 and IICIE=1) for transmit data
4. initialize RAM variables used to achieve the routine shown in Fig11-12
5. write IICC1 to enable TX
6. write IICC1 to enable Master
7. write IICD address of target slave

What do steps 3 and 4 mean ("initialize RAM" ) ? For step 3 I initialized IICEN and IICIE as mentioned in the paranthesis, but for step 4 I do not recognize what is meant with the RAM-variables "used to achieve the routine shown in Fig11-12"... What is meant here?

somebody got any tips/hints?

mg,
Johannes

PS: as you may have noted I'm new to IIC, didn't use it up to now.

[ohanica · Accepted solution]

Hello!


The MST bit cannot be set when the IICS_IICIF flag is set. This is the reason why I could not modify it when I wanted to (this behaviour is not mentioned in the datasheet).

An initialization code that works fine for me is the following

Code:

  IICA         = 0x0A;// set my own slave address  IICC1_TXAK   = 1;   // don't generate ACK by master  IICC1_MST    = 0;   // slave mode  IICF         = 0x4B;// IIC-frequency setting 0x60 for 100 kHz  IICC1_IICEN  = 1;   // enable IIC  IICS_IICIF   = 1;   //clear interrupts

Writing a byte is done by the following function:

Code:

void writeByteIIC(UINT8 slaveAddr, UINT8 regAddr, UINT8 dataByte)
{

 slaveAddr = slaveAddr & 0xFE; // make R/W-bit  = 0, so master transmits to slave
 IICC1_TX   = 1;     // set transmit mode
 IICC1_MST  = 1;     // START signal

 //send slave address
 IICD = slaveAddr;   //write data to Bus
 while (!IICS_IICIF);//wait for IICIF flag
 IICS_IICIF = 1;     //clear the interrupt flag IICIF by writing logic one
 while (IICS_RXAK);  //wait for acknowledge

 //send data address
 IICD = regAddr;     //write data to Bus
 while (!IICS_IICIF);//wait for IICIF flag
 IICS_IICIF = 1;
 while (IICS_RXAK);  //wait for acknowledge

 //send data
 IICD = dataByte;    //write data to Bus
 while (!IICS_IICIF);//wait for IICIF flag
 IICS_IICIF = 1;
 while (IICS_RXAK);  //wait for acknowledge

 //STOP signal
 IICC_MST  = 0;

}

 

Including such simple examples in the datasheet would be a great help for beginners.

greetx,
Johannes Philippi