CC2541，使用I2C从三轴加速度传感器读取数据
想用CC2541从三轴加速度传感器MMA8451读取三轴加速度传感器，不知到TI官方有没有这样的demo，keyfob上使用的三轴加速度传感器是什么，有没有现成的利用CC2541从三轴加速度传感器读取加速度的demo。
有例称，可能不是MMA8451，不过可以去参考！
可以给个链接吗，谢谢了
是怎么样的例程，给个链接给我，先谢谢了
keyfob上用的是博世的BMA250，sensortag上用的是KXTJ9-1007。个人建议你用sensortag上的例程做修改，使用IIC通讯，而且传感器你也可以使用一样的型号，因为这个系列的传感器功耗很小，相同ODR下的功耗不到8451的一半。另外飞思卡尔也出新的低功耗的ACC了，你可以选个别的型号
例程的话，你可以去官网下载1.4的协议栈，安装上之后就有了。里边有很多例程 血压计的、sensortag的、simpleperipheral工程（keyfob）
/**************************************************************************//**
@file bma250.c
@brief Functions for accessing accelerometer BMA250 on CC2541 keyfob.
******************************************************************************/
/******************************************************************************
* INCLUDES
*/
#include <ioCC2541.h>
#include "bma250.h"
/******************************************************************************
* DEFINES
*/
// Accelerometer connected at (names in brackets are BMA250 names)
// P2_0 = VDD (VDD/VDDIO)
// P1_2 = CS_N (CSB)
// P1_3 = SCK (SCx)
// P1_4 = MISO (SDO)
// P1_5 = MOSI (SDx)
// P1_7 = (INT1)
#define CS P1_2
#define SCK P1_3
#define MISO P1_4
#define MOSI P1_5
#define CS_DISABLED 1
#define CS_ENABLED 0
// OR bitmask into reg (read, modify, write)
#define ACC_INT_ENABLE(reg, bm) { uint8 val; accReadReg((reg),&val); \
val |= (bm); accWriteReg((reg),val); }
// AND inverted bitmask into reg (read, modify write)
#define ACC_INT_DISABLE(reg, bm) { uint8 val; accReadReg((reg),&val); \
val &= ~(bm); accWriteReg((reg),val); }
/******************************************************************************
* FUNCTION PROTOTYPES
*/
void spiWriteByte(uint8 write);
void spiReadByte(uint8 *read, uint8 write);
/******************************************************************************
* LOCAL VARIABLES
*/
static uint8 acc_initialized = FALSE;
/******************************************************************************
* FUNCTIONS
*/
/**************************************************************************//**
* @fn accInit(void)
*
* @brief Initialize SPI interface and BMA250 accelerometer.
*
* @return void
******************************************************************************/
void accInit(void)
{
//*** Enable Accelerometer power ***
P2DIR |= 0x01; // Set P2_0 as output high
P2SEL &= ~0x01;
P2 |= 0x01;
//*** Setup USART 0 SPI at alternate location 2 ***
// USART 0 at alternate location 2
PERCFG |= 0x01;
// Peripheral function on SCK, MISO and MOSI (P1_3-5)
P1SEL |= 0x38;
// Configure CS (P1_2) as output
P1DIR |= 0x04;
CS = CS_DISABLED;
//*** Setup the SPI interface ***
// SPI master mode
U0CSR = 0x00;
// Negative clock polarity, Phase: data out on CPOL -> CPOL-inv
// data in on CPOL-inv -> CPOL
// MSB first
U0GCR = 0x20;
// SCK frequency = 3MHz (MBA250 max=10MHz, CC254x max = 4MHz)
U0GCR |= 0x10;
U0BAUD = 0x80;
// *** Configure accelerometer ***
// Wait 2ms for accelerometer to power up and settle
WAIT_MS(2);
// Disable all interrupts
ACC_INT_DISABLE(ACC_INT_ENABLE0, 0xFF);
ACC_INT_DISABLE(ACC_INT_ENABLE1, 0xFF);
// Set 2G range
accWriteReg(ACC_RANGE, ACC_RANGE_2G);
// Filter detection bandwidth (Time between samples = 1/(2*filter_bw))
accWriteReg(ACC_BW, ACC_BW_250HZ);
#ifdef ENABLE_BMA250_INTERRUPT
// *** New data interrupt on INT1, active high ***
// INT1 as push-pull, active high
accWriteReg(ACC_INT_PIN_BEHAVIOR, ACC_INT1_LVL);
// Map New data interrupt to INT1
accWriteReg(ACC_INT_MAPPING1, ACC_INT1_MAP_DATA);
// Enable new data interrupts
ACC_INT_ENABLE(ACC_INT_ENABLE1, ACC_INT_DATA_EN);
#endif
acc_initialized = TRUE;
} // accInit
/**************************************************************************//**
* @fn accStop(void)
*
* @brief Sets the BMA250 accelerometer in low-power mode.
*
* @return void
******************************************************************************/
void accStop(void)
{
if (acc_initialized) {
// We cheat and simply turn off power to the accelerometer
P2_0 = 0x00; // If init has been run this pin is already output.
acc_initialized = FALSE;
}
}
/**************************************************************************//**
* @fn accWriteReg(uint8 reg, uint8 val)
*
* @brief Write one byte to a sensor register
*
* @param reg Register address
* @param val Value to write
*
* @return void
******************************************************************************/
void accWriteReg(uint8 reg, uint8 val)
{
CS = CS_ENABLED;
spiWriteByte(reg); // Write address
spiWriteByte(val); // Write value
CS = CS_DISABLED;
}
/**************************************************************************//**
* @fn accReadReg(uint8 reg, uint8 *pVal)
*
* @brief Read one byte from a sensor register
*
* @param reg Register address
* @param val Pointer to destination of read value
*
* @return void
******************************************************************************/
void accReadReg(uint8 reg, uint8 *pVal)
{
CS = CS_ENABLED;
spiWriteByte(0x80|reg); // Write address
spiReadByte(pVal, 0xFF); // Write dummy data and read returned value
CS = CS_DISABLED;
}
/**************************************************************************//**
* @fn accReadAcc(int16 *pXVal, int16 *pYVal, int16 *pZVal)
*
* @brief Read x, y and z acceleration data in one operation.
*
* @param pXVal Pointer to destination of read out X acceleration
* @param pYVal Pointer to destination of read out Y acceleration
* @param pZVal Pointer to destination of read out Z acceleration
*
* @return void
******************************************************************************/
void accReadAcc(int8 *pXVal, int8 *pYVal, int8 *pZVal)
{
int8 readout[6] = {0,0,0,0,0,0};
// Read all data from accelerometer
CS = CS_ENABLED;
spiWriteByte(0x80|ACC_X_LSB); // Write start address
for(uint8 i = 0; i<6; i++)
{
spiReadByte((uint8 *)&readout[i], 0xFF); // Read byte
}
CS = CS_DISABLED;
// Use only most significant byte of each channel.
*pXVal = readout[1];
*pYVal = readout[3];
*pZVal = readout[5];
} // accReadAcc
/**************************************************************************//**
* @fn accReadAcc(int16 *pXVal, int16 *pYVal, int16 *pZVal)
*
* @brief Read x, y and z acceleration data in one operation.
*
* @param pXVal Pointer to destination of read out X acceleration
* @param pYVal Pointer to destination of read out Y acceleration
* @param pZVal Pointer to destination of read out Z acceleration
*
* @return void
******************************************************************************/
void accReadAcc16(int16 *pXVal, int16 *pYVal, int16 *pZVal)
{
int8 readout[6] = {0,0,0,0,0,0};
// Read all data from accelerometer
CS = CS_ENABLED;
spiWriteByte(0x80|ACC_X_LSB); // Write start address
for(uint8 i = 0; i<6; i++)
{
spiReadByte((uint8 *)&readout[i], 0xFF); // Read byte
}
CS = CS_DISABLED;
// Merge high byte (8b) and low bits (2b) into 16b signed destination
*pXVal = ( (((uint8)readout[0]) >> 6) | ((int16)(readout[1]) << 2) );
*pYVal = ( (((uint8)readout[2]) >> 6) | ((int16)(readout[3]) << 2) );
*pZVal = ( (((uint8)readout[4]) >> 6) | ((int16)(readout[5]) << 2) );
} // accReadAcc16
/**************************************************************************//**
* @fn spiWriteByte(uint8 write)
*
* @brief Write one byte to SPI interface
*
* @param write Value to write
******************************************************************************/
void spiWriteByte(uint8 write)
{
U0CSR &= ~0x02; // Clear TX_BYTE
U0DBUF = write;
while (!(U0CSR & 0x02)); // Wait for TX_BYTE to be set
}
/**************************************************************************//**
* @fn spiReadByte(uint8 *read, uint8 write)
*
* @brief Read one byte from SPI interface
*
* @param read Read out value
* @param write Value to write
******************************************************************************/
void spiReadByte(uint8 *read, uint8 write)
{
U0CSR &= ~0x02; // Clear TX_BYTE
U0DBUF = write; // Write address to accelerometer
while (!(U0CSR & 0x02)); // Wait for TX_BYTE to be set
*read = U0DBUF; // Save returned value
}
/******************************************************************************
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这个是spi工作模式的！