When the right side-up and X=0,Y=0, the value that Z axle read is 40H. According to the datasheet of MMA8451QR1: it’s different form the stadand value.
I would like to ask that:
1).What do the values that X,Y,Z read out belong to ? How to handle them?
The mode that following program set is rapid read mode while X,Z,Y just read one byte.
Code: Select all
#include <msp430.h>
#include "MMA8451Q_register.h"
unsigned char reg[2];
int temp1, temp2, temp3, temp4, temp5, temp6;
void delay(int value)
{
volatile unsigned int i;
i = value; // SW Delay
do
i--;
while (i != 0);
}
int readiic(unsigned char address)
{
// unsigned char temp;
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition: start and write slave adress
while (!(IFG2 & UCB0TXIFG))
; // Over the process of waiting for writing address
// IFG2 &= ~UCB0TXIFG;
UCB0TXBUF = address;
while (!(IFG2 & UCB0TXIFG))
; // Over the process of waiting for writing address
// IFG2 &= ~UCB0TXIFG;
UCB0CTL1 &= ~UCTR; // set to be read mode
UCB0CTL1 |= UCTXSTT; // restart + r + SLAVE ADRESS
while (!(IFG2 & UCB0RXIFG))
; // Over the process of waiting for writing address if here I wrote it as: while (!(IFG2 & UCB0TXIFG))，UCB0TXIFG is 0，the program cannot operate
// IFG2 &= ~UCB0RXIFG;
/* reg[0] = UCB0RXBUF;
while (!(IFG2 & UCB0RXIFG))
; // over the process of waiting receive data
// IFG2 &= ~UCB0RXIFG;
reg[1] = UCB0RXBUF;
while (!(IFG2 & UCB0RXIFG)) */
temp1 = UCB0RXBUF;
while (!(IFG2 & UCB0RXIFG))
;
temp2 = UCB0RXBUF;
while (!(IFG2 & UCB0RXIFG))
;
UCB0CTL1 |= UCTXSTP; // Nack + stop communicate
return temp2;
}
void write(unsigned char regAddr, unsigned char value)
{
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
while (!(IFG2 & UCB0TXIFG))
; // WAIT send over
// IFG2 &= ~UCB0TXIFG;
UCB0TXBUF = regAddr; // Write the register address
while (!(IFG2 & UCB0TXIFG))
; // WAIT send over
IFG2 &= ~UCB0TXIFG;
UCB0TXBUF = value;
while (!(IFG2 & UCB0TXIFG))
;
IFG2 &= ~UCB0TXIFG;
UCB0CTL1 |= UCTXSTP; // Transmit STOP
delay(100);
}
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P6DIR |= BIT4;
// 0000 0110
P3SEL |= 0x06; // Assign I2C pins to USCI_B0 P3_1,P3_2
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 = 0x1C; // SA0=0 , Slave Address is 1CH
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
P2DIR |= BIT3; //set P2_3 to be output
P2OUT |= BIT3; // P2_3 , enable blue VCC,Raising reset pin，make it at the normal state
P3SEL |= BIT4 + BIT5; // set P3_4 ,P3_5 to have special function；
DCOCTL = 0; // Select lowest DCOx and MODx settings
BCSCTL1 = CALBC1_1MHZ; // Set DCO
DCOCTL = CALDCO_1MHZ;
UCA0CTL1 |= UCSWRST;
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 8; //clock 1MHZ，the baud rate is 115200 refer to datasheet
UCA0BR1 = 0;
UCA0MCTL |= UCBRS2 + UCBRS0; // 5
UCA0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCA0RXIE;
__enable_interrupt();
while (1)
{
int k;
P6OUT ^= BIT4;
delay(20000);
MMA8451Q_INIT();
UCA0TXBUF = temp3;
while (UCA0STAT & UCBUSY)
;
for(k=0;k<=30;k++)
delay(6000);
UCA0TXBUF = temp4;
while (UCA0STAT & UCBUSY)
;
for(k=0;k<=30;k++)
delay(6000);
UCA0TXBUF = temp5;
while (UCA0STAT & UCBUSY)
;
for(k=0;k<=30;k++)
delay(6000);
UCA0TXBUF = temp6;
while (UCA0STAT & UCBUSY)
;
for(k=0;k<=30;k++)
delay(6000);
}
}
void MMA8451Q_INIT(void)
{
write(CTRL_REG1, 0X03); // Acceleration sensor activation patterns+ Fast Read Mode(Single Byte Data)
temp3 = readiic(WHO_AM_I); // the data read out should be 0X1A(DEVICE ID)
delay(20);
temp4 = readiic(OUT_X_MSB); // read X speed dat
delay(20);
temp5 = readiic(OUT_Y_MSB); //read Y speed dat
delay(20);
temp6 = readiic(OUT_Z_MSB); // read Z speed dat
delay(20);
}
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USC(void)
{
while (UCA0STAT & UCBUSY)
;
UCA0TXBUF = UCA0RXBUF;C:\Users\Administrator\Desktop
}