I2C important points to be noted for SDA left shift

hello,

Just a comment - the USCI I2CSA is indeed right-justified. This is mentioned in the register description in the family user's guide: 

I2CSAx

The I2CSAx bits contain the slave address of the external device to be addressed by the USCI_Bx module. It is only used in master mode. The address is right justified. In 7-bit slave addressing mode, bit 6 is the MSB and bits 9-7 are ignored. In 10-bit slave addressing mode, bit 9 is the MSB.

 -Priya

hi,

    Thank you priya for the comment , I dint take a look at that particular register , bcoz  by seeing examples from the SLAC123C I was using that register directly and so thought it as a hardware problem ok any ways thank you for the reply it helped me  a lot to correct myself  but there must be a detailed explanation regarding that in the user guide regading how to correct it or use it.

another thing I want to ask ? is there a device specific data sheet for MSP430F2274 other than SLAU144e if so please provide me with the links.

and regarding the I2C problem I posted the code below for interfacing EEprom AT24C512 with MSP430F2274   //actual device address for AT24c512 is 0XA0 but Im using 0x50 because of Right justified

I am able to establish communication between MSP and EEPROm but I am not getting written data correctly from exact location 0x0000 word address from EEPROM

      #include "msp430x22x4.h"      

void USCI_init(void);      
void I2C_Tx(void);             //actual device address for AT24c512 is 0XA0 but Im using 0x50 because of Right justified
 void I2C_Rx(void);
    volatile  unsigned char c[2]={0};
 

void main(void)
{
   WDTCTL = WDTPW + WDTHOLD;                 // Stop Watchdog Timer
     P3DIR |=0xFF;
     P3OUT |=0x00;

// Assign I2C pins to USCI_B0
  USCI_init();
 
  // ##################UART mode to display the Date and time thru COM port ###########################
 
                         // P3.4,5 = USCI_A0 TXD/RXD
   
  UCA0CTL1 |= UCSSEL_2;                     // SMCLK
  UCA0BR0 = 0x41;                            // 1MHz 9600
  UCA0BR1 = 0x03;                              // 1MHz 9600
  UCA0MCTL = UCBRS0;                        // Modulation UCBRSx = 1
  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
  //IE2 |= UCA0RXIE;    
 
    // ##################UART mode to display the Date and time thru COM port ###########################
 

  I2C_Tx();

I2C_Rx();
   }

void USCI_init(void)
{

  UCB0CTL1 |= UCSWRST;                      // Enable SW reset
  UCB0CTL0 = UCMST+UCMODE_3+UCSYNC;         // I2C Master, synchronous mode
  UCB0CTL1 = UCSSEL_2+UCSWRST;              // Use SMCLK, keep SW reset
  P3SEL |= 0x16; 
  UCB0BR0 = 12;                             // fSCL = SMCLK/12 = ~100kHz
  UCB0BR1 = 0;
  UCB0I2CSA = 0x50;                         // Set slave address //actual device address for AT24c512 is 0XA0 but Im using 0x50 because of Right justified
  UCB0CTL1 &= ~UCSWRST;                     // Clear SW reset, resume operation
 

}

void I2C_Tx(void)
{
                  UCB0I2CSA = 0x50;                         // Set slave address //actual device address for AT24c512 is 0XA0 but Im using 0x50 because of Right justified
                    
            UCB0CTL1 |= UCTR+ UCTXSTT;     //start condition
             while(UCB0CTL1 & UCTXSTT);    //Check for Device Acknowledgement
            while(!UCB0TXIFG);
             UCB0TXBUF = 0x00;   //word address
                while(!(UCB0TXIFG));
                  
                   UCB0TXBUF =0x00;        //word address            
                 while(!(UCB0TXIFG));
                     UCB0TXBUF ='B';                //data           
                 while(!(UCB0TXIFG));
                    UCB0TXBUF ='C';                //data         
                while(!(UCB0TXIFG));
                   UCB0TXBUF ='D';                  //data          
                          UCB0CTL1 |=UCTXSTP;   //stop condition
          
                    }
          

     void I2C_Rx(void)   //Random Read for EEPROM
  { 
     
                    // Set slave address and  DUMMY WRITE

                 UCB0I2CSA = 0x50;  //slave address 
             
    UCB0CTL1 |= UCTR+ UCTXSTT;     //start condition
               //write to UCB0TXBUF  after SLAVE address
         while(UCB0CTL1 & UCTXSTT);    //Check for Device Acknowledgement
            while(!(UCB0TXIFG));      // check data start condition);
          
             UCB0TXBUF = 0x00;    //word address from that particular location where written
               while(!(UCB0TXIFG));      // check data start condition);
         
           //Random Read for EEPROM
        UCB0TXBUF = 0x00;     //word address   from that particular location where written
              
           UCB0I2CSA = 0x50;  //slave address
           UCB0CTL1 &=~UCTR;       //REceive mode
           UCB0CTL1 |=UCTXSTT;  //Re-START condition
      
          while(!(UCB0RXIFG));
           c[0]=UCB0RXBUF;   //first data byte
            while(!(UCB0RXIFG));

            UCA0TXBUF=UCB0RXBUF;  //2nd data byte
              while(!(UCB0RXIFG));
           

         UCA0TXBUF=UCB0RXBUF; // 3rd data byte
                  
           UCB0CTL1 |=UCTXSTP;      ///sTOP condition
                       
  }
  

Shalom!

 Did you even get the 2274 to interface the AT24C512 correctly without bit banging.

If so could you share the code?

Thanks

Shalom!

I am using the AQ430 Quadrovox compiler and looked at thie include file for the 2274/2 chip.

I  understand that there are two UART units A0 & B0 of which B0 conatins the I2c and SPI units.

There are different pins for the normal serial and the I2C I/O but I see only one set of interrupts (TX & RX).

Does this mean that I can not use the normal A0 uart at the same time as the B0 I2C unit?

Can I use the B0 I2c unit at the same time of the A0 uart in polling mode?

If not I will have to just bit bang the pins as I must have the normal uart available at all times in this projects.

Thanks If anyone can enlighten me!

Yes I got the interface between  EEPROm ( using I2C)  and 2274 plz check te codes from my posts on I2c related u will find the codes