I2C通信UCB1

两路代码基本一样，下面是port mapping 的代码
void Port_Mapping(void)
{
__disable_interrupt(); // Disable Interrupts before altering Port Mapping registers
PMAPPWD = 0x02D52; // Enable Write-access to modify port mapping registers
#ifdef PORT_MAP_RECFG
PMAPCTL = PMAPRECFG; // Allow reconfiguration during runtime
#endif
P4MAP1 = PM_UCB1SDA;
P4MAP2 = PM_UCB1CLK;
PMAPPWD = 0; // Disable Write-Access to modify port mapping registers
#ifdef PORT_MAP_EINT
__enable_interrupt(); // Re-enable all interrupts
#endif
}
调用Port_Mapping后，进行 P4OUT |= 0x06; 就会出现时钟和数据信号缓慢拉低的情况，并且无法检测到时钟信号和数据信号
正常的UCB0在完成I2C配置前都保持高电平，只有检测到起始位UCB0CTL1 |= UCTR + UCTXSTT;后才出现时钟信号和数据信号