TI中文支持网利用的是I2C例程：msp430g2xx3_uscib0_i2c_03，编译环境是IAR，P1.6为SCL，P1.7为SDA，利用示波器检测两引脚，执行 UCB0CTL1 |= UCTR + UCTXSTT;语句后 ，还一直是高电平。求各位大佬帮忙看一下，蟹蟹！~
程序如下：
#include <msp430.h>
const unsigned char Sine_Tab[] =
{ 0xE5};
int main(void)
{ WDTCTL = WDTPW + WDTHOLD; P1DIR |=BIT0; UCB0CTL1 |= UCSWRST; UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;
P1SEL |= BIT6 + BIT7; P1SEL2|= BIT6 + BIT7;
P1REN |= BIT6 + BIT7;
UCB0CTL1 = UCSSEL_2 + UCSWRST; UCB0BR0 = 12; UCB0BR1 = 0; UCB0I2CSA = 0x40; UCB0CTL1 &= ~UCSWRST; IE2 |= UCB0TXIE; UCB0CTL1 |= UCTR + UCTXSTT; P1OUT ^=0x01;//p1.0 UCB0TXBUF = 0x010; __bis_SR_register(CPUOFF + GIE);}
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void)
#else
#error Compiler not supported!
#endif
{ static unsigned char ByteCtr;
UCB0TXBUF = Sine_Tab[ByteCtr++]; // Transmit data byte ByteCtr &= 0x1f; // Do not exceed table}
gaoyang9992006：
//******************************************************************************
//MSP430G2xx3 Demo - USCI_B0, I2C Master multiple byte TX/RX
//
//Description: I2C master communicates to I2C slave sending and receiving
//3 different messages of different length. I2C master will enter LPM0 mode
//while waiting for the messages to be sent/receiving using I2C interrupt.
//ACLK = NA, MCLK = SMCLK = DCO 16MHz.
//
//
//MSP430G25533.3V
//-----------------/|\ /|\
///|\ |||4.7k
//|||4.7k |
//---|RST|||
//||||
//|P1.6|---|---+- I2C Clock (UCB0SCL)
//|||
//|P1.7|---+----- I2C Data (UCB0SDA)
//||
//||
//
//Nima Eskandari
//Texas Instruments Inc.
//April 2017
//Built with CCS V7.0
//******************************************************************************#include <msp430.h>
#include <stdint.h>
#include <stdbool.h>//******************************************************************************
// Example Commands ************************************************************
//******************************************************************************#define SLAVE_ADDR0x48/* CMD_TYPE_X_SLAVE are example commands the master sends to the slave.* The slave will send example SlaveTypeX buffers in response.** CMD_TYPE_X_MASTER are example commands the master sends to the slave.* The slave will initialize itself to receive MasterTypeX example buffers.* */#define CMD_TYPE_0_SLAVE0
#define CMD_TYPE_1_SLAVE1
#define CMD_TYPE_2_SLAVE2#define CMD_TYPE_0_MASTER3
#define CMD_TYPE_1_MASTER4
#define CMD_TYPE_2_MASTER5#define TYPE_0_LENGTH1
#define TYPE_1_LENGTH2
#define TYPE_2_LENGTH6#define MAX_BUFFER_SIZE20/* MasterTypeX are example buffers initialized in the master, they will be* sent by the master to the slave.* SlaveTypeX are example buffers initialized in the slave, they will be* sent by the slave to the master.* */uint8_t MasterType2 [TYPE_2_LENGTH] = {'F', '4', '1', '9', '2', 'B'};
uint8_t MasterType1 [TYPE_1_LENGTH] = { 8, 9};
uint8_t MasterType0 [TYPE_0_LENGTH] = { 11};uint8_t SlaveType2 [TYPE_2_LENGTH] = {0};
uint8_t SlaveType1 [TYPE_1_LENGTH] = {0};
uint8_t SlaveType0 [TYPE_0_LENGTH] = {0};//******************************************************************************
// General I2C State Machine ***************************************************
//******************************************************************************typedef enum I2C_ModeEnum{IDLE_MODE,NACK_MODE,TX_REG_ADDRESS_MODE,RX_REG_ADDRESS_MODE,TX_DATA_MODE,RX_DATA_MODE,SWITCH_TO_RX_MODE,SWITHC_TO_TX_MODE,TIMEOUT_MODE
} I2C_Mode;/* Used to track the state of the software state machine*/
I2C_Mode MasterMode = IDLE_MODE;/* The Register Address/Command to use*/
uint8_t TransmitRegAddr = 0;/* ReceiveBuffer: Buffer used to receive data in the ISR* RXByteCtr: Number of bytes left to receive* ReceiveIndex: The index of the next byte to be received in ReceiveBuffer* TransmitBuffer: Buffer used to transmit data in the ISR* TXByteCtr: Number of bytes left to transfer* TransmitIndex: The index of the next byte to be transmitted in TransmitBuffer* */
uint8_t ReceiveBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t RXByteCtr = 0;
uint8_t ReceiveIndex = 0;
uint8_t TransmitBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t TXByteCtr = 0;
uint8_t TransmitIndex = 0;/* I2C Write and Read Functions *//* For slave device with dev_addr, writes the data specified in *reg_data** dev_addr: The slave device address.*Example: SLAVE_ADDR* reg_addr: The register or command to send to the slave.*Example: CMD_TYPE_0_MASTER* *reg_data: The buffer to write*Example: MasterType0* count: The length of *reg_data*Example: TYPE_0_LENGTH**/
I2C_Mode I2C_Master_WriteReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data, uint8_t count);/* For slave device with dev_addr, read the data specified in slaves reg_addr.* The received data is available in ReceiveBuffer** dev_addr: The slave device address.*Example: SLAVE_ADDR* reg_addr: The register or command to send to the slave.*Example: CMD_TYPE_0_SLAVE* count: The length of data to read*Example: TYPE_0_LENGTH**/
I2C_Mode I2C_Master_ReadReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t count);
void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count);I2C_Mode I2C_Master_ReadReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t count)
{/* Initialize state machine */MasterMode = TX_REG_ADDRESS_MODE;TransmitRegAddr = reg_addr;RXByteCtr = count;TXByteCtr = 0;ReceiveIndex = 0;TransmitIndex = 0;/* Initialize slave address and interrupts */UCB0I2CSA = dev_addr;IFG2 &= ~(UCB0TXIFG + UCB0RXIFG);// Clear any pending interruptsIE2 &= ~UCB0RXIE;// Disable RX interruptIE2 |= UCB0TXIE;// Enable TX interruptUCB0CTL1 |= UCTR + UCTXSTT;// I2C TX, start condition__bis_SR_register(CPUOFF + GIE);// Enter LPM0 w/ interruptsreturn MasterMode;}I2C_Mode I2C_Master_WriteReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data, uint8_t count)
{/* Initialize state machine */MasterMode = TX_REG_ADDRESS_MODE;TransmitRegAddr = reg_addr;//Copy register data to TransmitBufferCopyArray(reg_data, TransmitBuffer, count);TXByteCtr = count;RXByteCtr = 0;ReceiveIndex = 0;TransmitIndex = 0;/* Initialize slave address and interrupts */UCB0I2CSA = dev_addr;IFG2 &= ~(UCB0TXIFG + UCB0RXIFG);// Clear any pending interruptsIE2 &= ~UCB0RXIE;// Disable RX interruptIE2 |= UCB0TXIE;// Enable TX interruptUCB0CTL1 |= UCTR + UCTXSTT;// I2C TX, start condition__bis_SR_register(CPUOFF + GIE);// Enter LPM0 w/ interruptsreturn MasterMode;
}void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count)
{uint8_t copyIndex = 0;for (copyIndex = 0; copyIndex < count; copyIndex++){dest[copyIndex] = source[copyIndex];}
}//******************************************************************************
// Device Initialization *******************************************************
//******************************************************************************void initClockTo16MHz()
{if (CALBC1_16MHZ==0xFF)// If calibration constant erased{while(1);// do not load, trap CPU!!}DCOCTL = 0;// Select lowest DCOx and MODx settingsBCSCTL1 = CALBC1_16MHZ;// Set DCODCOCTL = CALDCO_16MHZ;
}void initGPIO()
{P1DIR |= BIT0 + BIT1 + BIT2 + BIT3 + BIT4;P1OUT &= ~(BIT0 + BIT1 + BIT2 + BIT3 + BIT4);P1SEL |= BIT6 + BIT7;// Assign I2C pins to USCI_B0P1SEL2|= BIT6 + BIT7;// Assign I2C pins to USCI_B0
}void initI2C()
{UCB0CTL1 |= UCSWRST;// Enable SW resetUCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;// I2C Master, synchronous modeUCB0CTL1 = UCSSEL_2 + UCSWRST;// Use SMCLK, keep SW resetUCB0BR0 = 160;// fSCL = SMCLK/160 = ~100kHzUCB0BR1 = 0;UCB0I2CSA = SLAVE_ADDR;// Slave AddressUCB0CTL1 &= ~UCSWRST;// Clear SW reset, resume operationUCB0I2CIE |= UCNACKIE;
}//******************************************************************************
// Main ************************************************************************
// Send and receive three messages containing the example commands *************
//******************************************************************************int main(void) {WDTCTL = WDTPW | WDTHOLD;// Stop watchdog timerinitClockTo16MHz();initGPIO();initI2C();I2C_Master_WriteReg(SLAVE_ADDR, CMD_TYPE_0_MASTER, MasterType0, TYPE_0_LENGTH);I2C_Master_WriteReg(SLAVE_ADDR, CMD_TYPE_1_MASTER, MasterType1, TYPE_1_LENGTH);I2C_Master_WriteReg(SLAVE_ADDR, CMD_TYPE_2_MASTER, MasterType2, TYPE_2_LENGTH);I2C_Master_ReadReg(SLAVE_ADDR, CMD_TYPE_0_SLAVE, TYPE_0_LENGTH);CopyArray(ReceiveBuffer, SlaveType0, TYPE_0_LENGTH);I2C_Master_ReadReg(SLAVE_ADDR, CMD_TYPE_1_SLAVE, TYPE_1_LENGTH);CopyArray(ReceiveBuffer, SlaveType1, TYPE_1_LENGTH);I2C_Master_ReadReg(SLAVE_ADDR, CMD_TYPE_2_SLAVE, TYPE_2_LENGTH);CopyArray(ReceiveBuffer, SlaveType2, TYPE_2_LENGTH);__bis_SR_register(LPM0_bits + GIE);return 0;
}//******************************************************************************
// I2C Interrupt For Received and Transmitted Data******************************
//******************************************************************************#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void)
#else
#error Compiler not supported!
#endif
{if (IFG2 & UCB0RXIFG)// Receive Data Interrupt{//Must read from UCB0RXBUFuint8_t rx_val = UCB0RXBUF;if (RXByteCtr){ReceiveBuffer[ReceiveIndex++] = rx_val;RXByteCtr--;}if (RXByteCtr == 1){UCB0CTL1 |= UCTXSTP;}else if (RXByteCtr == 0){IE2 &= ~UCB0RXIE;MasterMode = IDLE_MODE;__bic_SR_register_on_exit(CPUOFF);// Exit LPM0}}else if (IFG2 & UCB0TXIFG)// Transmit Data Interrupt{switch (MasterMode){case TX_REG_ADDRESS_MODE:UCB0TXBUF = TransmitRegAddr;if (RXByteCtr)MasterMode = SWITCH_TO_RX_MODE;// Need to start receiving nowelseMasterMode = TX_DATA_MODE;// Continue to transmision with the data in Transmit Bufferbreak;case SWITCH_TO_RX_MODE:IE2 |= UCB0RXIE;// Enable RX interruptIE2 &= ~UCB0TXIE;// Disable TX interruptUCB0CTL1 &= ~UCTR;// Switch to receiverMasterMode = RX_DATA_MODE;// State state is to receive dataUCB0CTL1 |= UCTXSTT;// Send repeated startif (RXByteCtr == 1){//Must send stop since this is the N-1 bytewhile((UCB0CTL1 & UCTXSTT));UCB0CTL1 |= UCTXSTP;// Send stop condition}break;case TX_DATA_MODE:if (TXByteCtr){UCB0TXBUF = TransmitBuffer[TransmitIndex++];TXByteCtr--;}else{//Done with transmissionUCB0CTL1 |= UCTXSTP;// Send stop conditionMasterMode = IDLE_MODE;IE2 &= ~UCB0TXIE;// disable TX interrupt__bic_SR_register_on_exit(CPUOFF);// Exit LPM0}break;default:__no_operation();break;}}
}//******************************************************************************
// I2C Interrupt For Start, Restart, Nack, Stop ********************************
//******************************************************************************#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0RX_VECTOR))) USCIAB0RX_ISR (void)
#else
#error Compiler not supported!
#endif
{if (UCB0STAT & UCNACKIFG){UCB0STAT &= ~UCNACKIFG;// Clear NACK Flags}if (UCB0STAT & UCSTPIFG)//Stop or NACK Interrupt{UCB0STAT &=~(UCSTTIFG + UCSTPIFG + UCNACKIFG);//Clear START/STOP/NACK Flags}if (UCB0STAT & UCSTTIFG){UCB0STAT &= ~(UCSTTIFG);//Clear START Flags}
}
gaoyang9992006：
回复 gaoyang9992006:
//****************************************************************************** //MSP430G2xx3 Demo - USCI_B0, I2C Slave multiple byte TX/RX // //Description: I2C master communicates to I2C slave sending and receiving //3 different messages of different length. (This is the slave code). The //slave will be in LPM0 mode, waiting for the master to initiate the //communication. The slave will send/receive bytes based on the master's //request. The slave will handle I2C bytes sent/received using the //I2C interrupt. //ACLK = NA, MCLK = SMCLK = DCO 16MHz. // // //MSP430G25533.3V //-----------------/|\ /|\ ///|\ |||4.7k //|||4.7k | //---|RST||| //|||| //|P1.6|---|---+- I2C Clock (UCB0SCL) //||| //|P1.7|---+----- I2C Data (UCB0SDA) //|| //|| // //Nima Eskandari //Texas Instruments Inc. //April 2017 //Built with CCS V7.0 //******************************************************************************#include <msp430.h>#include <stdint.h>//****************************************************************************** // Example Commands ************************************************************ //******************************************************************************#define SLAVE_ADDR0x48/* CMD_TYPE_X_SLAVE are example commands the master sends to the slave.* The slave will send example SlaveTypeX buffers in response.** CMD_TYPE_X_MASTER are example commands the master sends to the slave.* The slave will initialize itself to receive MasterTypeX example buffers.* */#define CMD_TYPE_0_SLAVE0 #define CMD_TYPE_1_SLAVE1 #define CMD_TYPE_2_SLAVE2#define CMD_TYPE_0_MASTER3 #define CMD_TYPE_1_MASTER4 #define CMD_TYPE_2_MASTER5#define TYPE_0_LENGTH1 #define TYPE_1_LENGTH2 #define TYPE_2_LENGTH6#define MAX_BUFFER_SIZE20/* MasterTypeX are example buffers initialized in the master, they will be* sent by the master to the slave.* SlaveTypeX are example buffers initialized in the slave, they will be* sent by the slave to the master.* */uint8_t MasterType2 [TYPE_2_LENGTH] = {0}; uint8_t MasterType1 [TYPE_1_LENGTH] = { 0, 0}; uint8_t MasterType0 [TYPE_0_LENGTH] = { 0};uint8_t SlaveType2 [TYPE_2_LENGTH] = {'A', 'B', 'C', 'D', '1', '2'}; uint8_t SlaveType1 [TYPE_1_LENGTH] = {15, 16}; uint8_t SlaveType0 [TYPE_0_LENGTH] = {12};//****************************************************************************** // General I2C State Machine *************************************************** //******************************************************************************typedef enum I2C_ModeEnum{IDLE_MODE,NACK_MODE,TX_REG_ADDRESS_MODE,RX_REG_ADDRESS_MODE,TX_DATA_MODE,RX_DATA_MODE,SWITCH_TO_RX_MODE,SWITHC_TO_TX_MODE,TIMEOUT_MODE } I2C_Mode;/* Used to track the state of the software state machine*/ I2C_Mode SlaveMode = RX_REG_ADDRESS_MODE;/* The Register Address/Command to use*/ uint8_t ReceiveRegAddr = 0;/* ReceiveBuffer: Buffer used to receive data in the ISR* RXByteCtr: Number of bytes left to receive* ReceiveIndex: The index of the next byte to be received in ReceiveBuffer* TransmitBuffer: Buffer used to transmit data in the ISR* TXByteCtr: Number of bytes left to transfer* TransmitIndex: The index of the next byte to be transmitted in TransmitBuffer* */ uint8_t ReceiveBuffer[MAX_BUFFER_SIZE] = {0}; uint8_t RXByteCtr = 0; uint8_t ReceiveIndex = 0; uint8_t TransmitBuffer[MAX_BUFFER_SIZE] = {0}; uint8_t TXByteCtr = 0; uint8_t TransmitIndex = 0;/* Initialized the software state machine according to the received cmd** cmd: The command/register address received* */ void I2C_Slave_ProcessCMD(uint8_t cmd);/* The transaction between the slave and master is completed. Uses cmd* to do post transaction operations. (Place data from ReceiveBuffer* to the corresponding buffer based in the last received cmd)** cmd: The command/register address corresponding to the completed* transaction*/ void I2C_Slave_TransactionDone(uint8_t cmd); void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count);void I2C_Slave_ProcessCMD(uint8_t cmd) {ReceiveIndex = 0;TransmitIndex = 0;RXByteCtr = 0;TXByteCtr = 0;switch (cmd){case (CMD_TYPE_0_SLAVE)://Send slave device id (This device's id)SlaveMode = TX_DATA_MODE;TXByteCtr = TYPE_0_LENGTH;//Fill out the TransmitBufferCopyArray(SlaveType0, TransmitBuffer, TYPE_0_LENGTH);IE2 &= ~UCB0RXIE;// Disable RX interruptIE2 |= UCB0TXIE;// Enable TX interruptbreak;case (CMD_TYPE_1_SLAVE)://Send slave device time (This device's time)SlaveMode = TX_DATA_MODE;TXByteCtr = TYPE_1_LENGTH;//Fill out the TransmitBufferCopyArray(SlaveType1, TransmitBuffer, TYPE_1_LENGTH);IE2 &= ~UCB0RXIE;// Disable RX interruptIE2 |= UCB0TXIE;// Enable TX interruptbreak;case (CMD_TYPE_2_SLAVE)://Send slave device location (This device's location)SlaveMode = TX_DATA_MODE;TXByteCtr = TYPE_2_LENGTH;//Fill out the TransmitBufferCopyArray(SlaveType2, TransmitBuffer, TYPE_2_LENGTH);IE2 &= ~UCB0RXIE;// Disable RX interruptIE2 |= UCB0TXIE;// Enable TX interruptbreak;case (CMD_TYPE_0_MASTER):SlaveMode = RX_DATA_MODE;RXByteCtr = TYPE_0_LENGTH;IE2 &= ~UCB0TXIE;// Disable RX interruptIE2 |= UCB0RXIE;// Enable TX interruptbreak;case (CMD_TYPE_1_MASTER):SlaveMode = RX_DATA_MODE;RXByteCtr = TYPE_1_LENGTH;IE2 &= ~UCB0TXIE;// Disable RX interruptIE2 |= UCB0RXIE;// Enable TX interruptbreak;case (CMD_TYPE_2_MASTER):SlaveMode = RX_DATA_MODE;RXByteCtr = TYPE_2_LENGTH;IE2 &= ~UCB0TXIE;// Disable RX interruptIE2 |= UCB0RXIE;// Enable TX interruptbreak;default:__no_operation();break;} }void I2C_Slave_TransactionDone(uint8_t cmd) {switch (cmd){case (CMD_TYPE_0_SLAVE)://Slave device id was sent(This device's id)break;case (CMD_TYPE_1_SLAVE)://Slave device time was sent(This device's time)break;case (CMD_TYPE_2_SLAVE)://Send slave device location (This device's location)break;case (CMD_TYPE_0_MASTER):CopyArray(ReceiveBuffer, MasterType0, TYPE_0_LENGTH);break;case (CMD_TYPE_1_MASTER):CopyArray(ReceiveBuffer, MasterType1, TYPE_1_LENGTH);break;case (CMD_TYPE_2_MASTER):CopyArray(ReceiveBuffer, MasterType2, TYPE_2_LENGTH);break;default:__no_operation();break;} }void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count) {uint8_t copyIndex = 0;for (copyIndex = 0; copyIndex < count; copyIndex++){dest[copyIndex] = source[copyIndex];} }//****************************************************************************** // Device Initialization ******************************************************* //******************************************************************************void initClockTo16MHz() {if (CALBC1_16MHZ==0xFF)// If calibration constant erased{while(1);// do not load, trap CPU!!}DCOCTL = 0;// Select lowest DCOx and MODx settingsBCSCTL1 = CALBC1_16MHZ;// Set DCODCOCTL = CALDCO_16MHZ; }void initGPIO() {P1SEL |= BIT6 + BIT7;// Assign I2C pins to USCI_B0P1SEL2|= BIT6 + BIT7;// Assign I2C pins to USCI_B0 }void initI2C() {UCB0CTL1 |= UCSWRST;// Enable SW resetUCB0CTL0 = UCMODE_3 + UCSYNC;// I2C Slave, synchronous modeUCB0I2COA = SLAVE_ADDR;// Own AddressUCB0CTL1 &= ~UCSWRST;// Clear SW reset, resume operationUCB0I2CIE |= UCSTPIE + UCSTTIE;// Enable STT and STP interruptIE2 |= UCB0RXIE;// Enable RX interrupt }//****************************************************************************** // Main ************************************************************************ // Enters LPM0 and waits for I2C interrupts. The data sent from the master is* // then interpreted and the device will respond accordingly* //******************************************************************************int main(void) {WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timerinitClockTo16MHz();initGPIO();initI2C();__bis_SR_register(LPM0_bits + GIE);return 0; }//****************************************************************************** // I2C Interrupt For Received and Transmitted Data****************************** //******************************************************************************#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__) #pragma vector = USCIAB0TX_VECTOR __interrupt void USCIAB0TX_ISR(void) #elif defined(__GNUC__) void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void) #else #error Compiler not supported! #endif {if (IFG2 & UCB0RXIFG)// Receive Data Interrupt{//Must read from UCB0RXBUFuint8_t rx_val = UCB0RXBUF;switch (SlaveMode){case (RX_REG_ADDRESS_MODE):ReceiveRegAddr = rx_val;I2C_Slave_ProcessCMD(ReceiveRegAddr);break;case (RX_DATA_MODE):ReceiveBuffer[ReceiveIndex++] = rx_val;RXByteCtr--;if (RXByteCtr == 0){//Done Receiving MSGSlaveMode = RX_REG_ADDRESS_MODE;IE2 &= ~(UCB0TXIE);IE2 |= UCB0RXIE;// Enable RX interruptI2C_Slave_TransactionDone(ReceiveRegAddr);}break;default:__no_operation();break;}}else if (IFG2 & UCB0TXIFG)// Transmit Data Interrupt{//Must write to UCB0TXBUFswitch (SlaveMode){case (TX_DATA_MODE):UCB0TXBUF = TransmitBuffer[TransmitIndex++];TXByteCtr--;if (TXByteCtr == 0){//Done Transmitting MSGSlaveMode = RX_REG_ADDRESS_MODE;IE2 &= ~(UCB0TXIE);IE2 |= UCB0RXIE;// Enable RX interruptI2C_Slave_TransactionDone(ReceiveRegAddr);}break;default:__no_operation();break;}} }//****************************************************************************** // I2C Interrupt For Start, Restart, Nack, Stop ******************************** //******************************************************************************#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__) #pragma vector = USCIAB0RX_VECTOR __interrupt void USCIAB0RX_ISR(void) #elif defined(__GNUC__) void __attribute__ ((interrupt(USCIAB0RX_VECTOR))) USCIAB0RX_ISR (void) #else #error Compiler not supported! #endif {if (UCB0STAT & UCSTPIFG)//Stop or NACK Interrupt{UCB0STAT &=~(UCSTTIFG + UCSTPIFG + UCNACKIFG);//Clear START/STOP/NACK Flags}if (UCB0STAT & UCSTTIFG){UCB0STAT &= ~(UCSTTIFG);//Clear START Flags} }
chenhui tang：
回复 gaoyang9992006:
我也是用的例程啊，没有起始条件信号变化是咋回事，求解惑啊，蟹蟹
xyz549040622：
回复 chenhui tang:
你这是完全I2C没有工作起来呀？时钟信号都没有，例程是肯定不会错误的，你循环发个数据抓波形看看。
chenhui tang：
回复 xyz549040622:
嗯嗯，我也认为程序不会出错，我在 UCB0CTL1 |= UCTR + UCTXSTT后面设置断点，或者单步运行调试，示波器始终无变化（高电平），有可能是系统时钟配置问题？我这个例程好像没有配置时钟。
xyz549040622：
回复 chenhui tang:
时钟肯定是需要配置的，时钟是单片机的心脏。另外，你全速运行抓波形，示波器加触发就好了，有时候加断点，不容易抓到波形。
chenhui tang：
回复 xyz549040622:
不太明白您所说的加触发是什么意思？我设置了下降沿触发，触发源是通道信号。这样子还是没有波形（一直是高电平）
Susan Yang：
回复 chenhui tang:
int main(void) {WDTCTL = WDTPW + WDTHOLD;// Stop Watchdog TimerP1SEL |= BIT6 + BIT7;// Assign I2C pins to USCI_B0P1SEL2|= BIT6 + BIT7;// Assign I2C pins to USCI_B0UCB0CTL1 |= UCSWRST;// Enable SW resetUCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;// I2C Master, synchronous modeUCB0CTL1 = UCSSEL_2 + UCSWRST;// Use SMCLK, keep SW resetUCB0BR0 = 12;// fSCL = SMCLK/12 = ~100kHzUCB0BR1 = 0;UCB0I2CSA = 0x4c;// Set slave addressUCB0CTL1 &= ~UCSWRST;// Clear SW reset, resume operationIE2 |= UCB0TXIE;// Enable TX ready interruptUCB0CTL1 |= UCTR + UCTXSTT;// I2C TX, start conditionUCB0TXBUF = 0x010;// Write DAC control byte__bis_SR_register(CPUOFF + GIE);// Enter LPM0 w/ interrupts }
chenhui tang：
回复 Susan Yang:
我找到问题了：由于设置了内部上拉电阻，画蛇添足了（P1REN |= BIT6 + BIT7）。取消了设置之后，起始信号的波形就正常了。
因为我并没有在主机和从机之间接4.7k的上拉电阻，所以利用430的内置上拉。因此不太明白的是：为什么有了这个内置上拉电阻就反而不正常了（一直是高电平）呢？难道是阻值太大？之后我取消内置上拉电阻却正常工作，难道不需要上拉电阻？
