As i have seen many friends try to get help regarding interfacing ADXL345 with MSP430G2553 here is the ready reference samplecode for the same ......
// Interfacing ADXL345 accelerometer with MSP430G2553 with I2C communication
//
// /|\ /|\
// ADXL345 10k 10k MSP430G2xx3
// slave | | master
// ----------------- | | -----------------
// | SDA|<-|---+->|P3.1/UCB0SDA XIN|-
// | | | | |
// | | | | XOUT|-
// | SCL|<-+----->|P3.2/UCB0SCL |
// | | | |
//
// Attribute: Code modified from I2C multiple byte TX/RX Master example by
// D. Dang
// Texas Instruments Inc.
//
// Code Made By :
// Prof. Ravi Butani
// Marwadi Education Foundation, Rajkot GUJARAT-INDIA
// ravi.butani@marwadieducation.edu.in
//
// Code Released under Creative Commons By-SA license
// Visit http://creativecommons.org/licenses/by-sa/3.0/deed.en_US to know more about license
// Built with CCS Version 5.1.0
//******************************************************************************
#include <msp430.h>
#define NUM_BYTES_TX 2 // How many bytes?
#define NUM_BYTES_RX 6
#define ADXL_345 0x53
int RXByteCtr, RPT_Flag = 0,x1,y1,z1; // enables repeated start when 1
volatile unsigned char RxBuffer[6]; // Allocate 6 byte of RAM
unsigned char *PRxData; // Pointer to RX data
unsigned char TXByteCtr, RX = 0;
unsigned char MSData[3];
void Setup_TX(unsigned char);
void Setup_RX(unsigned char);
void Transmit(unsigned char,unsigned char);
void Receive(void);
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1DIR |= BIT0;
// Init sequence for ADXL345
//Transmit process
Setup_TX(ADXL_345);
RPT_Flag = 1;
Transmit(0x2D,0x00);
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
//Transmit process
Setup_TX(ADXL_345);
RPT_Flag = 1;
Transmit(0x2D,0x10);
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
//Transmit process
Setup_TX(ADXL_345);
RPT_Flag = 1;
Transmit(0x2D,0x08);
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
// Un-comment next block to change range of ADXL345
/*
Setup_TX(ADXL_345);
RPT_Flag = 1;
Transmit(0x31,0x01); // Range Select at add 0x31 write 0x00 for 2g(default)/ 0x01 for 4g/ 0x02 for 8g/ 0x03 for 16g
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
*/
while(1){
//Transmit process
Setup_TX(ADXL_345);
RPT_Flag = 1;
Transmit(0x32,0xFE); // Request Data from ADXL345 in 2g Range 10Bit resolution
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
//Receive process
Setup_RX(ADXL_345);
Receive();
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
x1 = (((int)RxBuffer[1]) << 8) | RxBuffer[0];
y1 = (((int)RxBuffer[3]) << 8) | RxBuffer[2];
z1 = (((int)RxBuffer[5]) << 8) | RxBuffer[4];
// now You have XYZ axis reading in x1,x2,x3 variable....Bingo... you can play with it as you like....
// Below if sense x and y angle and Red led is on if its more then 45 or less then -45...
// you can put your own condition here...
if ((x1 > 128) || (y1 > 128) || (x1 < -128) || (y1 < -128))
{
P1OUT |= BIT0; // red led on
}
else
{
P1OUT &= ~BIT0; // red led off
}
__delay_cycles(10000); // sample rate ~100 samples/sec
// you can change by changing delay
}
}
//-------------------------------------------------------------------------------
// The USCI_B0 data ISR is used to move received data from the I2C slave
// to the MSP430 memory. It is structured such that it can be used to receive
// any 2+ number of bytes by pre-loading RXByteCtr with the byte count.
//-------------------------------------------------------------------------------
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
if(RX == 1){ // Master Recieve?
RXByteCtr--; // Decrement RX byte counter
if (RXByteCtr)
{
*PRxData++ = UCB0RXBUF; // Move RX data to address PRxData
}
else
{
if(RPT_Flag == 0)
UCB0CTL1 |= UCTXSTP; // No Repeated Start: stop condition
if(RPT_Flag == 1){ // if Repeated Start: do nothing
RPT_Flag = 0;
}
*PRxData = UCB0RXBUF; // Move final RX data to PRxData
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}}
else{ // Master Transmit
if (TXByteCtr) // Check TX byte counter
{
UCB0TXBUF = MSData[TXByteCtr]; // Load TX buffer
TXByteCtr--; // Decrement TX byte counter
}
else
{
if(RPT_Flag == 1){
RPT_Flag = 0;
TXByteCtr = NUM_BYTES_TX; // Load TX byte counter
__bic_SR_register_on_exit(CPUOFF);
}
else{
UCB0CTL1 |= UCTXSTP; // I2C stop condition
IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
}
}
}
void Setup_TX(unsigned char Dev_ID){
_DINT();
RX = 0;
IE2 &= ~UCB0RXIE;
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent// Disable RX interrupt
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = Dev_ID; // Slave Address is 048h
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0TXIE; // Enable TX interrupt
}
void Setup_RX(unsigned char Dev_ID){
_DINT();
RX = 1;
IE2 &= ~UCB0TXIE;
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = Dev_ID; // Slave Address is 048h
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0RXIE; // Enable RX interrupt
}
void Transmit(unsigned char Reg_ADD,unsigned char Reg_DAT){
MSData[2]= Reg_ADD;
MSData[1]= Reg_DAT;
TXByteCtr = NUM_BYTES_TX; // Load TX byte counter
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
}
void Receive(void){
PRxData = (unsigned char *)RxBuffer; // Start of RX buffer
RXByteCtr = NUM_BYTES_RX-1; // Load RX byte counter
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
UCB0CTL1 |= UCTXSTT; // I2C start condition
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
}
