Hi there,
I've had my launch pad for about a week now and I've been able to flash lights and all those sorts of things. Now I am trying to use the SPI perpherial to interface the MSP430G2553 chip with an Analog Devices ADXL345 accelerometer.
I have been through the sample code provided in the wiki plus many other versions I have found and have just about got my head around how to set some functions up to work. I have also tried the Energia software and SPI examples included. This helped a lot and I finially managed to get some sort of data flowing. But I'm pretty sure it was all nonsense and the Energia environment is too basic to help debug so I've been trying to put together the semi working code from the Energia example and some other examples in a Code Composer Studio Project.
I seam to be able to transmit some information as I can see it on the oscilloscope (whether or not it is correct I'm not sure) but the code gets stuck in a while loop after transmission when it is waiting for a response and I don't know why as it seamed to work when it was within the Energia example. All I am trying to do at the moment is get the device ID so I know the correct information is being sent and received.
Could anyone offer some advise on this? I don't really know what to try next.
I've attached my main.c file for viewing.
//Include Files
#include "msp430g2553.h"
#include <stdint.h>
//ADXL345 Register Addresses
#define DEVID 0x00 //Device ID Register
#define THRESH_TAP 0x1D //Tap Threshold
#define OFSX 0x1E //X-axis offset
#define OFSY 0x1F //Y-axis offset
#define OFSZ 0x20 //Z-axis offset
#define DURATION 0x21 //Tap Duration
#define LATENT 0x22 //Tap latency
#define WINDOW 0x23 //Tap window
#define THRESH_ACT 0x24 //Activity Threshold
#define THRESH_INACT 0x25 //Inactivity Threshold
#define TIME_INACT 0x26 //Inactivity Time
#define ACT_INACT_CTL 0x27 //Axis enable control for activity and inactivity detection
#define THRESH_FF 0x28 //free-fall threshold
#define TIME_FF 0x29 //Free-Fall Time
#define TAP_AXES 0x2A //Axis control for tap/double tap
#define ACT_TAP_STATUS 0x2B //Source of tap/double tap
#define BW_RATE 0x2C //Data rate and power mode control
#define POWER_CTL 0x2D //Power Control Register
#define INT_ENABLE 0x2E //Interrupt Enable Control
#define INT_MAP 0x2F //Interrupt Mapping Control
#define INT_SOURCE 0x30 //Source of interrupts
#define DATA_FORMAT 0x31 //Data format control
#define DATAX0 0x32 //X-Axis Data 0
#define DATAX1 0x33 //X-Axis Data 1
#define DATAY0 0x34 //Y-Axis Data 0
#define DATAY1 0x35 //Y-Axis Data 1
#define DATAZ0 0x36 //Z-Axis Data 0
#define DATAZ1 0x37 //Z-Axis Data 1
#define FIFO_CTL 0x38 //FIFO control
#define FIFO_STATUS 0x39 //FIFO status
//Other definitions
#define SPI_MODE_0 (UCCKPH) /* CPOL=0 CPHA=0 */
#define SPI_MODE_1 (0) /* CPOL=0 CPHA=1 */
#define SPI_MODE_2 (UCCKPL | UCCKPH) /* CPOL=1 CPHA=0 */
#define SPI_MODE_3 (UCCKPL) /* CPOL=1 CPHA=1 */
#define SPI_MODE_MASK (UCCKPL | UCCKPH)
#define DELAY_1000NS __delay_cycles(200);�������� // required delay is minimum 250ns
//*************Extra functions*******************
/**
* spi_initialize() - Configure USCI UCB0 for SPI mode
*
* P2.0 - CS (active low)
* P1.5 - SCLK
* P1.6 - MISO aka SOMI
* P1.7 - MOSI aka SIMO
*
*/
void spi_initialize(void)
{
UCB0CTL1 = UCSWRST | UCSSEL_2; // Put USCI in reset mode, source USCI clock from SMCLK
UCB0CTL0 = SPI_MODE_0 | UCMSB | UCSYNC | UCMST; // Use SPI MODE 0 - CPOL=0 CPHA=0
P1OUT |= (BIT5 | BIT7); // SPI output pins low
P1SEL |= BIT5 | BIT6 | BIT7; // configure P1.5, P1.6, P1.7 for USCI
P1SEL2 |= BIT5 | BIT6 | BIT7; // more required SPI configuration
UCB0BR0 = 4 & 0xFF; // set initial speed to 4MHz
UCB0BR1 = (4 >> 8 ) & 0xFF;
UCB0CTL1 &= ~UCSWRST; // release USCI for operation
P2DIR |= BIT0; //P2.0 set as output
P2OUT |= BIT0; //P2.0 set high
}
/***SPI_MODE_0
* spi_set_divisor() - set new clock divider for USCI
*
* USCI speed is based on the SMCLK divided by BR0 and BR1
*
*/
void spi_set_divisor(const uint16_t clkdiv)
{
UCB0CTL1 |= UCSWRST; // go into reset state
UCB0BR0 = clkdiv & 0xFF;
UCB0BR1 = (clkdiv >> 8 ) & 0xFF;
UCB0CTL1 &= ~UCSWRST; // release for operation
}
/**
* spi_set_datamode() - mode 0 - 3
*/
void spi_set_datamode(const uint8_t mode)
{
UCB0CTL1 |= UCSWRST; // go into reset state
switch(mode) {
case 0: /* SPI_MODE0 */
UCB0CTL0 = (UCB0CTL0 & ~SPI_MODE_MASK) | SPI_MODE_0;
break;
case 1: /* SPI_MODE1 */
UCB0CTL0 = (UCB0CTL0 & ~SPI_MODE_MASK) | SPI_MODE_1;
break;
case 2: /* SPI_MODE2 */
UCB0CTL0 = (UCB0CTL0 & ~SPI_MODE_MASK) | SPI_MODE_2;
break;
case 3: /* SPI_MODE3 */
UCB0CTL0 = (UCB0CTL0 & ~SPI_MODE_MASK) | SPI_MODE_3;
break;
default:
break;
}
UCB0CTL1 &= ~UCSWRST; // release for operation
}
/**
* spi_send() - send a byte and receive response
*/
uint8_t spi_send(const uint8_t _data)
{
while (!(UC0IFG & UCB0TXIFG)); // wait for previous tx to complete
UCB0TXBUF = _data; // setting TXBUF clears the TXIFG flag
while (!(UC0IFG & UCB0RXIFG)); // wait for an rx character?
return UCB0RXBUF; // reading clears RXIFG flag
}
//************Write data to SPI bus************
void spiWrite(char addr, char data)
{
P2OUT ^= BIT0; //Toggle P2.0 -> Set low to initiate transfer
spi_send(addr);
spi_send(data);
P2OUT |= BIT0; //P2.0 set high again to stop transfer
}
//***********Read data from address************
char spiRead(char reg_addr)
{
char value;
P2OUT ^= BIT0;
value = spi_send(reg_addr);
P2OUT |= BIT0;
return(value); //Return the value from the register accessed
}
//**************Main function********************
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
spi_initialize();
spi_set_datamode(3);
char dataRead;
dataRead = spiRead(DEVID);
__delay_cycles(1000);
if (dataRead == DEVID){
P1OUT |= BIT0;
}
__delay_cycles(10000);
}
Thanks,
Alex