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刘洋 485 串口通讯 RS485
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RS485介绍
(1). RS-485的电气特性：采用差分信号负逻辑，逻辑"0”以两线间的电压差为+(2~6)V表示；逻辑"1"以两线间的电压差为-(2~6)V表示。接口信号电平比RS-232-C降低了，就不易损坏接口电路的芯片， 且该电平与TTL电平兼容，可方便与TTL电路连接。
(2). RS-485的数据最高传输速率为10Mbps。
(3). RS-485接口是采用平衡驱动器和差分接收器的组合，抗共模干扰能力增强，即抗噪声干扰性好。
(4). RS-485最大的通信距离约为1219m，最大传输速率为10Mbps，传输速率与传输距离成反比，在100KbpS的传输速率下，才可以达到最大的通信距离，如果需传输更长的距离，需要加485中继器。RS-485总线一般最大支持32个节点，如果使用特制的485芯片，可以达到128个或者256个节点，最大的可以支持到400个节点。
RS485原理图
UART1库函数
void UART1_DeInit(void);
void UART1_Init(uint32_t BaudRate, UART1_WordLength_TypeDef WordLength,
UART1_StopBits_TypeDef StopBits, UART1_Parity_TypeDef Parity,
UART1_SyncMode_TypeDef SyncMode, UART1_Mode_TypeDef Mode);
void UART1_Cmd(FunctionalState NewState);
void UART1_ITConfig(UART1_IT_TypeDef UART1_IT, FunctionalState NewState);
void UART1_HalfDuplexCmd(FunctionalState NewState);
void UART1_IrDAConfig(UART1_IrDAMode_TypeDef UART1_IrDAMode);
void UART1_IrDACmd(FunctionalState NewState);
void UART1_LINBreakDetectionConfig(UART1_LINBreakDetectionLength_TypeDef UART1_LINBreakDetectionLength);
void UART1_LINCmd(FunctionalState NewState);
void UART1_SmartCardCmd(FunctionalState NewState);
void UART1_SmartCardNACKCmd(FunctionalState NewState);
UART1库函数
void UART1_WakeUpConfig(UART1_WakeUp_TypeDef UART1_WakeUp);
void UART1_ReceiverWakeUpCmd(FunctionalState NewState);
uint8_t UART1_ReceiveData8(void);
uint16_t UART1_ReceiveData9(void);
void UART1_SendData8(uint8_t Data);
void UART1_SendData9(uint16_t Data);
void UART1_SendBreak(void);
void UART1_SetAddress(uint8_t UART1_Address);
void UART1_SetGuardTime(uint8_t UART1_GuardTime);
void UART1_SetPrescaler(uint8_t UART1_Prescaler);
FlagStatus UART1_GetFlagStatus(UART1_Flag_TypeDef UART1_FLAG);
void UART1_ClearFlag(UART1_Flag_TypeDef UART1_FLAG);
ITStatus UART1_GetITStatus(UART1_IT_TypeDef UART1_IT);
void UART1_ClearITPendingBit(UART1_IT_TypeDef UART1_IT);
UART3库函数
void UART3_DeInit(void);
void UART3_Init(uint32_t BaudRate, UART3_WordLength_TypeDef WordLength,
UART3_StopBits_TypeDef StopBits, UART3_Parity_TypeDef Parity,
UART3_Mode_TypeDef Mode);
void UART3_Cmd(FunctionalState NewState);
void UART3_ITConfig(UART3_IT_TypeDef UART3_IT, FunctionalState NewState);
void UART3_LINBreakDetectionConfig(UART3_LINBreakDetectionLength_TypeDef UART3_LINBreakDetectionLength);
void UART3_LINConfig(UART3_LinMode_TypeDef UART3_Mode,
UART3_LinAutosync_TypeDef UART3_Autosync,
UART3_LinDivUp_TypeDef UART3_DivUp);
void UART3_LINCmd(FunctionalState NewState);
void UART3_ReceiverWakeUpCmd(FunctionalState NewState);
void UART3_WakeUpConfig( UART3_WakeUp_TypeDef UART3_WakeUp);
uint8_t UART3_ReceiveData8(void);
uint16_t UART3_ReceiveData9(void);
void UART3_SendData8(uint8_t Data);
void UART3_SendData9(uint16_t Data);
void UART3_SendBreak(void);
void UART3_SetAddress(uint8_t UART3_Address);
FlagStatus UART3_GetFlagStatus(UART3_Flag_TypeDef UART3_FLAG);
void UART3_ClearFlag(UART3_Flag_TypeDef UART3_FLAG);
ITStatus UART3_GetITStatus(UART3_IT_TypeDef UART3_IT);
void UART3_ClearITPendingBit(UART3_IT_TypeDef UART3_IT);
【众拳】剑齿虎STM8开发板实验代码下载：
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