#define NEW_SBS_BOARD (1) /* serial port -- new board */ #if NEW_SBS_BOARD GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull ; GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable; GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt3 ; //this should be the serial port GPIO_Init (GPIO5, &GPIO_InitStructure); #else I think ''GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable;''it is not GPIO_IPConnected_Enable,Maybe it it GPIO_IPConnected_Disable Best Regards sunshan