Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

mcookfromwi — Mon, 25 Feb 2008 21:55:33 GMT

I have tried the "How to use the IIC module" as well as many other references but I seem unable to get IIC communications working between two 9S08's (one master addessed 0x11 and one slave addressed 0x33). I am successful in having a MASTER send a slave ID (0x33) but the slave software does not send a ACK back.

Is IIC comms possible without using interrupts? If so is there any examples I can try?

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

erooll — Wed, 27 Feb 2008 03:53:41 GMT

Could you show us, a piece of code that you are implementing.
Regards

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

mcookfromwi — Tue, 04 Mar 2008 05:14:41 GMT

The system seemed to loose my reply, this is my 2nd attempt.

/////////////////////////////////////////////////////////////
// Init_I2C
// sets up the iic port according to the state
//    selfAddress = slave address
//
void Init_I2C (unsigned char selfAddress)
{
    SOPT2_IICPS = 1; //Set the IICPS bit to redirect IIc pins
    IICC_IICEN = 1;//Enable IIC module
    IICC_TXAK = 1;// SEND ACK
    IICC_MST = 0;//SLAVE MODE
    IICA = selfAddress << 1;//set slave address in IICA //PTB6=SDA PTB7=SCL

    //set baud rate = BUSCLK/(2xMULTx(SCL Divider))
    //     MUX | ICR|
    //      \\ /////
    IICF = 0b10010000;//MUX=2,ICR=0x16 Speed=100Khz


    IICS_SRW = 0;//R/W bit = 0
    IICC_IICIE = 0;//Disable IIC interrupt

}

//////////////////////////////////////////////////////////////////////////////////
// IIC_write_byte
//    Writes command and data to slave
//   returns 0 if success
//           1 if error
byte IIC_write_byte (byte slave, byte command, byte data)
{
   byte temp;
   byte timeout = 0xFF;

   temp = (slave)<<1;     // Shift 7 bit slave address to the left 1 bit
                          // Bit 0 = 0 = Write
                          //     0 = 1 = Read
   IICC_TXAK = 0;         // RX/TX = 1; MS/SL = 1; TXAK = 0;
   IICC |= 0x30;          // Generate START & set TX = 1

   IICD = temp;           // select slave & set up for master transmit
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the flag
   while((IICS_RXAK)&&(timeout > 0))
      timeout --;      // check for RXAK

   if(timeout == 0) return 1;
   IICD = command;        // Send byte address
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the flag
   //while(IICS_RXAK);      // check for RXAK
   timeout = 0xFF;
   while((IICS_RXAK)&&(timeout > 0))
      timeout --;      // check for RXAK

   if(timeout == 0) return 1;
   IICD = data;
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the flag
   //while(IICS_RXAK);      // check for RXAK
   timeout = 0xFF;
   while((IICS_RXAK)&&(timeout > 0))
      timeout --;      // check for RXAK

   if(timeout == 0) return 1;
   IICS_IICIF=1;          // Clear the flag
   IICC_MST = 0;          // Generate STOP
   return 0;
}

//////////////////////////////////////////////////////////////////////////////////
// IIC_read_byte
//    Writes command to slave and returns data from slave
//   returns 0 if success
//           1 if error
byte IIC_read_byte (byte slave, byte command)
{
   byte RD_data;
   byte temp;

   temp = (slave)<<1;     // Shift 7 bit slave address to the left 1 bit
                          // Lsb Bit = 0 = Write
                          //         = 1 = Read
   IICC_TXAK = 0;
   IICC |= 0x30;          // Generate START
   IICD = temp;           // Address slave | (RW = 0), write to slave
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the int flag
   while(IICS_RXAK);      // Check for RXAK

   IICD = command;        // Send command to slave
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the int flag
   while(IICS_RXAK);      // Check for RXAK

   IICC_RSTA = 1;         // setup repeated start
   IICD = temp|1;         // (slave_address)|(RW = 1), read from slave
   while (!IICS_IICIF);   // wait until flag is set
   IICS_IICIF=1;          // Clear the int flag
   while(IICS_RXAK);      // Check for RXAK

   IICC_TX = 0;           // Setup to receive
   IICC_TXAK = 1;         // Acknowledge disable
   RD_data = IICD;        // Dummy read
   while (!IICS_IICIF);   // Wait until IBIF flag is set
   IICS_IICIF=1;          // Clear the flag
   IICC_MST = 0;          // Generate STOP
   RD_data = IICD;        // Read data
   return RD_data;
}

[[[Below is ione of my attempts at the slave read routine]]]

/////////////////////////////////////////////////////////////
// LL_Read()
byte LL_Read()
{
   //ToggleNum(0x33);
   //return 0x33;
   //IICC_TX = 0;
   //IICC_TXAK = 0;         // Acknowledge enable
   //IICS_IICIF=1;
   //IICC_MST = 0;//SLAVE MODE
   //while(IICS_TCF == 0)
   //   ToggleNum(IICS);
   if(IICS_IAAS)
   {
      IICC_TX = IICS_SRW; //SRW 0= slave receive, 1=slave transmit
      IICS_IAAS = 0;       // Setup to receive
       buffer[0] = IICD;      // Dummy read to initiate the read data byte
       buffer[1] = IICD;
       return 1;
   }
   //RD_data2 = IICD;         //read data
   //IICS_IICIF=1;           //Clear the flag
   //IICC_MST = 0;         //Generate STOP
   return 0;
}

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

Designer11 — Fri, 11 Jul 2008 23:34:24 GMT

Hi,

what method are you using to maintain the IIC communication, interrupt or polling ?

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Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.

Re: Basic IIC reading and writing between two 9S08's WITHOUT using interrupts.