MSP430F5529 I2C COMMUNICATION

I can READ from either 0x01 or 0x03 all are 16 bit registers .I want to read 16 bit data from specific register.

Hi Makkapati,

You could refer to the I2C example code. This will help you.

dev.ti.com/.../node

Hi allen its to recieve transmitted signal but we have to read particular register of slave here 0x03 register I have to read

Hi Makkapati,

You need to check the slave device datasheet of it I2C read protocol. Generally a read protocol is something like this.

Send a write command to write the special register you want read and re-start command and then send the read command and wait for slave transfer the data.

I HAVE TO READ 2 BYTES BUT HERE I COULD ABLE TO READ ONLY MSB 8 BITS OF DATA

>while (UCB0CTL1 & UCTXSTP);

Waiting for TXSTP to go low is not an effective way of waiting for completion, since TXSTP is not initially high. The Tx side might be working by accident, but you're almost certainly stopping the Rx side prematurely. Try replacing that with

> LPM0;  // Wait for completion.

You'll have to add this to the "case 0x0C":

>   __bic_SR_register_on_exit(LPM0_bits); // Exit active CPU

HI BRUCE i TRIED AS YOU SAID BUT EVEN COMMUNICATION IS NOT ESTABLISHED IT SEEMS TO BE IRRESPONSIVE PAGE.

#include <msp430.h>
int Data_In=0;
unsigned int RXByteCtr;
unsigned int Temperature;
volatile unsigned int RxBuffer[128];
void main(void)
{
volatile int i;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT // P1.0 output
P3SEL |= 0x03; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 |= UCSSEL_2; // Use SMCLK
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x40; // Slave Address is 048h
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
//UCB0IE |= UCRXIE;
UCB0IE |= UCTXIE;
UCB0IE |= UCSTPIE + UCSTTIE + UCRXIE;
volatile int c=1;
__enable_interrupt();
while(1)
{
//if(c%2==1)
//{
RXByteCtr = 2;
UCB0CTL1 |= UCTR + UCTXSTT;
//while (UCB0CTL1 & UCTXSTP);
LPM0;
UCB0CTL1 &=~UCTXSTP;
UCB0CTL1 &=~UCTR;
UCB0CTL1 |=UCTXSTT;
//while (UCB0CTL1 & UCTXSTP);
LPM0;
UCB0CTL1 &=~UCTXSTP;
// else if(c%2==0)
// {
// while (UCB0CTL1 & UCTXSTP);
//UCB0CTL1 |= UCTR + UCTXSTT;
//UCB0CTL1 &=~UCTXSTP;
//UCB0CTL1 |=UCTXSTT;
//UCB0CTL1 &=~UCTR;
//while (UCB0CTL1 & UCTXSTP);
// }
//UCB0CTL1 &=~UCTXSTP;
}
}
#pragma vector = USCI_B0_VECTOR
__interrupt void USCI_B0_ISR(void)
{
switch(UCB0IV){
case 0x0A:
RXByteCtr--; // Decrement RX byte counter
if (RXByteCtr)
{
Temperature |= UCB0RXBUF; // Move RX data to address PRxData
if (RXByteCtr == 1)
// MSB of temperature
Temperature |= UCB0RXBUF<< 8;
Temperature |= UCB0RXBUF;
UCB0CTL1 |= UCTXSTP; // Only one byte left?
// Generate I2C stop condition
}
else
{
// Move final RX data to PRxData
__bic_SR_register_on_exit(LPM0_bits); // Exit active CPU
}
break;
case 0x0C:
UCB0TXBUF = 0X03;
__bic_SR_register_on_exit(LPM0_bits);
break;
default:
break;
}
}

Hi Makkapati,

Makkapati Ganesh said:

if (RXByteCtr)
{
Temperature |= UCB0RXBUF; // Move RX data to address PRxData

When the second time go into ISR, the RxByteCtr=, the new RXBUF data will replace the low 8 bit of Temperature which has load the previous RXBUF data. 

YES HOW COULD I SEND THAT 

means how to store the lsb bit also

Hi Makkapati，

Judge first before proceeding, That is the logic problem. Do you have any problem of using the device?

logic problem as you told its only msb byte going through i2c bus..

Hi Makkapati,

Have you solved your problem? Get the fist 8 bit data and shift it to the high 8 bit of "int" variant.  Then get the next 8 bit data put it to the lower.

I DIDNT RESOLVED