lab-12-4619_m_i2c.c

MSP430FG4619的iic子程序

//******************************************************************************
//   MSP430xG461x Demo - USCI_B0 I2C Master TX multiple bytes to MSP430 Slave
//
//   Description: This demo connects two MSP430's via the I2C bus. The master
//   transmits to the slave. This is the master code. It continuously
//   transmits an array of data and demonstrates how to implement an I2C
//   master transmitter sending multiple bytes using the USCI_B0 TX interrupt.
//   ACLK = 32kHz, MCLK = SMCLK = TACLK = BRCLK = 1MHz
//
//                                 /|\  /|\
//                MSP430xG461x     10k  10k    MSP430xG461x
//                    slave         |    |        master
//              -----------------   |    |  -----------------
//            -|XIN  P3.1/UCB0SDA|<-|---+--|P3.1/UCB0SDA  XIN|-
//       32kHz |                 |  |      |                 | 32kHz
//            -|XOUT             |  |      |             XOUT|-
//             |     P3.2/UCB0SCL|<-+------|P3.2/UCB0SCL     |
//             |                 |         |                 |
//
//   Andreas Dannenberg/ M. Mitchell
//   Texas Instruments Inc.
//   October 2006
//   Built with IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include "msp430xG46x.h"

unsigned char *PTxData;                     // 发送数据指针
unsigned char TXByteCtr;
const unsigned char TxData[] =              // 发送的数据
{
  0x11,
  0x22,
  0x33,
  0x44,
  0x55
};

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // 关看门狗
  P3SEL |= 0x06;                            // 选择 I2C 功能
  UCB0CTL1 |= UCSWRST;                      // 使能 SW 复位
  UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;     // I2C 主机, 同步模式
  UCB0CTL1 = UCSSEL_2 + UCSWRST;            // SMCLK
  UCB0BR0 = 11;                             // fSCL = SMCLK/11 = 95.3kHz
  UCB0BR1 = 0;
  UCB0I2CSA = 0x48;                         // 从机地址 048h
  UCB0CTL1 &= ~UCSWRST;                     // 清 SW  
  IE2 |= UCB0TXIE;                          // 发送中断使能

  while (1)
  {
    PTxData = (unsigned char *)TxData;      // 发送数据起始地址
    TXByteCtr = sizeof TxData;              // 装载发送数据
    UCB0CTL1 |= UCTR + UCTXSTT;             // I2C 发送, 起始条件
    __bis_SR_register(CPUOFF + GIE);        // 开中断 进入低功耗 LPM0 
    while (UCB0CTL1 & UCTXSTP);             // 等待产生停止位
  }
}

//-------------------------------------------------------------------------
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
  if (TXByteCtr)                            // 校验正确 ？
  {
    UCB0TXBUF = *PTxData++;                 // 发送数据
    TXByteCtr--;                            // 数据个数自减1 
  }
  else
  {
    UCB0CTL1 |= UCTXSTP;                    // I2C 停止条件
    IFG2 &= ~UCB0TXIFG;                     // 清  USCI_B0 发送标志
    __bic_SR_register_on_exit(CPUOFF);      // 退出低功耗 LPM0
  }
}