情况 : 尝试在MSP430G2553与Pololu MinIMU-9 v5上面的SM6DS33(加速度传感器;地址为0x6B)之间的联系
根据说明文件Using the USCI I 2C Master(Rev.A)(SLAA382A) 对 TI_USCI_I2C_master.h 中的SDA_PIN 和 SCL_PIN 做了修改(改为P1.6与P1.7的地址依次为0x40,0x80)及include了MSP430G2553的头文件,但是在尝试使用Checking Presence of a Slave(检测线上的slave)范例程序的是时候程序卡在TI_USCI_I2C_slave_present function里的 while (UCB0CTL1 & UCTXSTP); // wait for STOP condition语句上,请问是否能够提供解答?
以下为程序文件:(红色荧光笔部分为做过修改的地方,黄色荧光笔为程序名字)
Main
#include "msp430g2553.h"
#include "TI_USCI_I2C_master.h"
#include "TI_USCI_I2C_master.c"
unsigned char timercounter;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
TI_USCI_I2C_transmitinit(0x6b,12);
_EINT();
if (!TI_USCI_I2C_slave_present(0x6b)){ // check for slave
while (1); // trap cpu if slave with address 0x11
// doesn't answer
}
P1DIR |=BIT0;
P1OUT |=BIT0;
//LPM0; // Enter LPM0 w/ interrupt
}
TI_USCI_I2C_master.h
#ifndef USCI_LIB
#define USCI_LIB
#define SDA_PIN 0x80 // msp430x255x UCB0SDA pin
#define SCL_PIN 0x40 // msp430x255x UCB0SCL pin
void TI_USCI_I2C_receiveinit(unsigned char slave_address, unsigned char prescale);
void TI_USCI_I2C_transmitinit(unsigned char slave_address, unsigned char prescale);
void TI_USCI_I2C_receive(unsigned char byteCount, unsigned char *field);
void TI_USCI_I2C_transmit(unsigned char byteCount, unsigned char *field);
unsigned char TI_USCI_I2C_slave_present(unsigned char slave_address);
unsigned char TI_USCI_I2C_notready();
#endif
TI_USCI_I2C_master.c
//#include "msp430x26x.h" // device specific header
//#include "msp430x22x4.h"
//#include "msp430x23x0.h"
//#include "msp430xG46x.h"
#include "msp430g2553.h"
// … // more devices are possible
#include "TI_USCI_I2C_master.h"
signed char byteCtr;
unsigned char *TI_receive_field;
unsigned char *TI_transmit_field;
//——————————————————————————
// void TI_USCI_I2C_receiveinit(unsigned char slave_address,// unsigned char prescale)
//
// This function initializes the USCI module for master-receive operation.//
// IN: unsigned char slave_address => Slave Address
// unsigned char prescale => SCL clock adjustment//—————————————————————————–
void TI_USCI_I2C_receiveinit(unsigned char slave_address, unsigned char prescale){
P3SEL |= SDA_PIN + SCL_PIN; // Assign I2C pins to USCI_B0
UCB0CTL1 = UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = prescale; // set prescaler
UCB0BR1 = 0;
UCB0I2CSA = slave_address; // set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB0I2CIE = UCNACKIE;
IE2 = UCB0RXIE; // Enable RX interrupt
}
//——————————————————————————
// void TI_USCI_I2C_transmitinit(unsigned char slave_address,// unsigned char prescale)
//
// This function initializes the USCI module for master-transmit operation.//
// IN: unsigned char slave_address => Slave Address
// unsigned char prescale => SCL clock adjustment//——————————————————————————
void TI_USCI_I2C_transmitinit(unsigned char slave_address, unsigned char prescale){
P3SEL |= SDA_PIN + SCL_PIN; // Assign I2C pins to USCI_B0
UCB0CTL1 = UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = prescale; // set prescaler
UCB0BR1 = 0;
UCB0I2CSA = slave_address; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB0I2CIE = UCNACKIE;
IE2 = UCB0TXIE; // Enable TX ready interrupt
}
//——————————————————————————
// void TI_USCI_I2C_receive(unsigned char byteCount, unsigned char *field)
//
// This function is used to start an I2C commuincation in master-receiver mode.//
// IN: unsigned char byteCount => number of bytes that should be read
// unsigned char *field => array variable used to store received data
//——————————————————————————
void TI_USCI_I2C_receive(unsigned char byteCount, unsigned char *field){
TI_receive_field = field;
if ( byteCount == 1 ){
byteCtr = 0 ;
__disable_interrupt();
UCB0CTL1 |= UCTXSTT; // I2C start condition
while (UCB0CTL1 & UCTXSTT); // Start condition sent?
UCB0CTL1 |= UCTXSTP; // I2C stop condition
__enable_interrupt();
} else if ( byteCount > 1 ) {
byteCtr = byteCount – 2 ;
UCB0CTL1 |= UCTXSTT; // I2C start condition
} else
while (1); // illegal parameter
}
//——————————————————————————
// void TI_USCI_I2C_transmit(unsigned char byteCount, unsigned char *field)
//
// This function is used to start an I2C commuincation in master-transmit mode.//
// IN: unsigned char byteCount => number of bytes that should be transmitted
// unsigned char *field => array variable. Its content will be sent.
//——————————————————————————
void TI_USCI_I2C_transmit(unsigned char byteCount, unsigned char *field){
TI_transmit_field = field;
byteCtr = byteCount;
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
}
//——————————————————————————
// unsigned char TI_USCI_I2C_slave_present(unsigned char slave_address)
//
// This function is used to look for a slave address on the I2C bus.//
// IN: unsigned char slave_address => Slave Address
// OUT: unsigned char => 0: address was not found,// 1: address found
//——————————————————————————
unsigned char TI_USCI_I2C_slave_present(unsigned char slave_address){
unsigned char ie2_bak, slaveadr_bak, ucb0i2cie, returnValue;
ucb0i2cie = UCB0I2CIE; // restore old UCB0I2CIE
ie2_bak = IE2; // store IE2 register
slaveadr_bak = UCB0I2CSA; // store old slave address
UCB0I2CIE &= ~ UCNACKIE; // no NACK interrupt
UCB0I2CSA = slave_address; // set slave address
IE2 &= ~(UCB0TXIE + UCB0RXIE); // no RX or TX interrupts
__disable_interrupt();
UCB0CTL1 |= UCTR + UCTXSTT + UCTXSTP; // I2C TX, start condition
while (UCB0CTL1 & UCTXSTP); // wait for STOP condition
returnValue = !(UCB0STAT & UCNACKIFG);
__enable_interrupt();
IE2 = ie2_bak; // restore IE2
UCB0I2CSA = slaveadr_bak; // restore old slave address
UCB0I2CIE = ucb0i2cie; // restore old UCB0CTL1
return returnValue; // return whether or not // a NACK occured
}
//——————————————————————————
// unsigned char TI_USCI_I2C_notready()
//
// This function is used to check if there is commuincation in progress.//
// OUT: unsigned char => 0: I2C bus is idle,// 1: communication is in progress
//——————————————————————————
unsigned char TI_USCI_I2C_notready(){
return (UCB0STAT & UCBBUSY);
}
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
{
if (UCB0STAT & UCNACKIFG){ // send STOP if slave sends NACK
UCB0CTL1 |= UCTXSTP;
UCB0STAT &= ~UCNACKIFG;
}
}
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
if (IFG2 & UCB0RXIFG){
if ( byteCtr == 0 ){
UCB0CTL1 |= UCTXSTP; // I2C stop condition
*TI_receive_field = UCB0RXBUF;
TI_receive_field++;
}
else {
*TI_receive_field = UCB0RXBUF;
TI_receive_field++;
byteCtr–;
}
}
else {
if (byteCtr == 0){
UCB0CTL1 |= UCTXSTP; // I2C stop condition
IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag
}
else {
UCB0TXBUF = *TI_transmit_field;
TI_transmit_field++;
byteCtr–;
}
}
}
灰小子:
1、没用过Pololu MinIMU-9。这个例程不是针对这个器件的,不知道和这个器件的iic时序要求是否兼容。一般应该问题不大,注意察看器件的iic要求。
2、UCB0CTL1 & UCTXSTP是用来等待iic总线空闲。建议用示波器或者逻辑分析仪观察一下iic通讯时序,来判断具体是什么情况。