源：STM32F407的硬件I2C

我使用的是STM32的固件庫。

硬件模塊使用之前必須配置其參數(shù)，I2C的配置如下：

void IIC_Config(void) {GPIO_InitTypeDef GPIO_InitStructure;I2C_InitTypeDef I2C_InitStructure;RCC_ClocksTypeDef rcc_clocks;/* GPIO Peripheral clock enable */RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA|RCC_AHB1Periph_GPIOB|RCC_AHB1Periph_GPIOC, ENABLE);RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1|RCC_APB1Periph_I2C2|RCC_APB1Periph_I2C3, ENABLE);/* Reset I2Cx IP */RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1|RCC_APB1Periph_I2C2|RCC_APB1Periph_I2C3, ENABLE);/* Release reset signal of I2Cx IP */RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1|RCC_APB1Periph_I2C2|RCC_APB1Periph_I2C3, DISABLE);/*I2C1 configuration*/GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1); //注意，此處不能合并寫成GPIO_PinSource6|GPIO_PinSource7 GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_I2C1);//PB6: I2C1_SCL PB7: I2C1_SDAGPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;GPIO_Init(GPIOB, &GPIO_InitStructure);/* I2C Struct Initialize */I2C_DeInit(I2C1);I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;I2C_InitStructure.I2C_OwnAddress1 = 0x00;I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;I2C_InitStructure.I2C_ClockSpeed = 100000;I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;I2C_Init(I2C1, &I2C_InitStructure);/* I2C Initialize */I2C_Cmd(I2C1, ENABLE);/*I2C2 configuration*/GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_I2C2); //注意，此處不能合并寫成GPIO_PinSource6|GPIO_PinSource7 GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_I2C2);//PB10: I2C2_SCL PB11: I2C2_SDAGPIO_InitStructure.GPIO_Pin = GPIO_Pin_10|GPIO_Pin_11;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;GPIO_Init(GPIOB, &GPIO_InitStructure);/* I2C Struct Initialize */I2C_DeInit(I2C2);I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;I2C_InitStructure.I2C_OwnAddress1 = 0x00;I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;I2C_InitStructure.I2C_ClockSpeed = 100000;I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;I2C_Init(I2C2, &I2C_InitStructure);/* I2C Initialize */I2C_Cmd(I2C2, ENABLE);/*I2C3 configuration*/GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_I2C3);GPIO_PinAFConfig(GPIOC, GPIO_PinSource9, GPIO_AF_I2C3);//PA8: I2C3_SCLGPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;GPIO_Init(GPIOA, &GPIO_InitStructure);//PC9: I2C3_SDAGPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;GPIO_Init(GPIOC, &GPIO_InitStructure);/* I2C Struct Initialize */I2C_DeInit(I2C3);I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;I2C_InitStructure.I2C_OwnAddress1 = 0x00;I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;I2C_InitStructure.I2C_ClockSpeed = 100000;I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;I2C_Init(I2C3, &I2C_InitStructure);/* I2C Initialize */I2C_Cmd(I2C3, ENABLE);/*超時設(shè)置*/RCC_GetClocksFreq(&rcc_clocks);ulTimeOut_Time = (rcc_clocks.SYSCLK_Frequency /10000); }

注意，I2C一定要加上超時的設(shè)置，否則當(dāng)IIC總線出錯時，沒有超時檢測可能造成MCU卡死在這里。

STM32F407的硬件I2C讀一個字節(jié)與STM32F103類似，代碼如下：

unsigned char I2C_Err=0; uint8_t I2C_ReadOneByte(I2C_TypeDef *I2Cx,uint8_t I2C_Addr,uint8_t Reg_addr) { uint8_t readout;u32 tmr;tmr = ulTimeOut_Time;while((--tmr)&&I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY));if(tmr==0) I2C_Err = 1;I2C_GenerateSTART(I2Cx, ENABLE);//發(fā)送I2C的START信號，接口自動從從設(shè)備編程主設(shè)備tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_MODE_SELECT)));if(tmr==0) I2C_Err = 1;I2C_Send7bitAddress(I2Cx,I2C_Addr,I2C_Direction_Transmitter);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx,I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)));if(tmr==0) I2C_Err = 1;I2C_SendData(I2Cx, Reg_addr);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx,I2C_EVENT_MASTER_BYTE_TRANSMITTED)));if(tmr==0) I2C_Err = 1;I2C_GenerateSTART(I2Cx, ENABLE);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_MODE_SELECT)));if(tmr==0) I2C_Err = 1;I2C_Send7bitAddress(I2Cx, I2C_Addr, I2C_Direction_Receiver);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED)));if(tmr==0) I2C_Err = 1; I2C_AcknowledgeConfig(I2Cx, DISABLE);I2C_GenerateSTOP(I2Cx, ENABLE);tmr = ulTimeOut_Time;while((--tmr)&&(!(I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED)))); /* EV7 */if(tmr==0) I2C_Err = 1;readout = I2C_ReceiveData(I2Cx);I2C_AcknowledgeConfig(I2Cx, ENABLE);return readout; }

I2C_ReadOneByte函數(shù)輸入?yún)?shù)有3個，分別是：I2Cx，表示使用的I2C編號，I2C_addr，表示從設(shè)備的I2C地址，reg_addr，表示要讀取的從設(shè)備寄存器地址。I2C_ReadOneByte的返回值就是I2C總線上讀取到的數(shù)據(jù)。讀I2C數(shù)據(jù)后需要檢查I2C_Err是否為0，若為0，表示讀取I2C數(shù)據(jù)時出錯（超時），讀到的數(shù)據(jù)可能不正確。

向從設(shè)備寫入一個字節(jié)的數(shù)據(jù)，代碼如下：

unsigned char I2C_Err=0; void I2C_WriteOneByte(I2C_TypeDef *I2Cx,uint8_t I2C_Addr,uint8_t Reg_addr,uint8_t value) {u32 tmr;tmr = ulTimeOut_Time;while(I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY));while((--tmr)&&I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY));if(tmr==0) I2C_Err = 1;I2C_GenerateSTART(I2Cx, ENABLE);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_MODE_SELECT))); if(tmr==0) I2C_Err = 1;I2C_Send7bitAddress(I2Cx, I2C_Addr, I2C_Direction_Transmitter);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)));if(tmr==0) I2C_Err = 1;I2C_SendData(I2Cx, Reg_addr);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED)));if(tmr==0) I2C_Err = 1;I2C_SendData(I2Cx, value);tmr = ulTimeOut_Time;while((--tmr)&&(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED)));if(tmr==0) I2C_Err = 1;I2C_GenerateSTOP(I2Cx, ENABLE);//I2C_AcknowledgeConfig(I2Cx, DISABLE); }

寫I2C函數(shù)比讀僅多了一個輸入?yún)?shù)，即要寫入的數(shù)據(jù)。同理，在函數(shù)執(zhí)行完成后，需要檢查I2C_Err是否為0以判斷I2C是否出錯。

有了讀1個字節(jié)和寫入1個字節(jié)的函數(shù)，當(dāng)需要一次性讀或?qū)懚鄠€數(shù)據(jù)時，可以在上述函數(shù)的基礎(chǔ)上擴展多字節(jié)操作。

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