GD32MCU硬件I2C学习（一)
1.1 硬件I2C介绍
在项目中遇见与MCU通信接口协议为I2C的设备时，可通过GPIO口软件模拟I2C和使用MCU自身的硬件I2C资源。两者各有优势，软件模拟可以不受GPIO口限制，也可以主控制器MCU的选择上降低成本，但也存在I2C设备对通信速率有特定的要求或者需要较高的传输速率时，会存在时序调试困难、start/stop/ack/noack/read/write等都需要软件实现、GPIO口翻转速率限制等原因导致软件模拟I2C通信速率有一定的限制。硬件I2C则不存在上述问题，I2C通信速率可配置100k/400k/1M(NXP芯片做到了3.4M），通信时序中的绝大部分都由硬件完成，我们只需要按照逻辑配置好相应的寄存器即可，但也存在受特定GPIO口限制、相应成本高等缺点。本文主要是基GD32MCU介绍硬件I2C的配置和注意的事项，关于I2C协议概念介绍只是简要提及。
1.2 GD32 mcu硬件I2C的主要特性
1、同一接口既可实现主机功能又可实现从机功能；
2、主从机之间的双向数据传输；
3、支持7位和10位的地址模式和广播寻址；
4、支持I2C多主机模式；
5、速率100k\400k\1M；
6、从机模式下可配置SCL主动拉低；
7、支持DMA模式；
8、支持SMBUS；
9、事件中断和错误中断；
10、支持PEC错误校验。
1.3 主机发送和接收实现（速率100k/400k/1M 地址10bit or 7bit)
//.h文件#ifndef MAIN_H#define MAIN_H#include "gd32f3x0.h"#define I2Cx_Pinx_AFx_BIT(gpiox,pinx,afx) (((uint32_t)gpiox)|((uint32_t)(pinx)<<4)|(uint32_t)(afx))/*send_slaver address*/typedef enum{ Send_7Address=0x42, Send_7Address_2=0x44, send_gual=0x00, Send_10Address=0x232}Send_Address_Enum;/*define pin speed enum*/typedef enum{ standard_speed=100000, High_speed=400000, More_HighSpeed=1000000}I2Cx_Speed_enum;/*define I2Cx SDA Pin enum*/typedef enum{ //define I2C0 I2C0_SDA_GPIOx1=I2Cx_Pinx_AFx_BIT(GPIOA,10,4), I2C0_SDA_GPIOx2=I2Cx_Pinx_AFx_BIT(GPIOB,7,1), I2C0_SDA_GPIOx3=I2Cx_Pinx_AFx_BIT(GPIOB,9,1), //define I2C1 I2C1_SDA_GPIOx4=I2Cx_Pinx_AFx_BIT(GPIOA,1,4), I2C1_SDA_GPIOx5=I2Cx_Pinx_AFx_BIT(GPIOB,11,1), I2C1_SDA_GPIOx6=I2Cx_Pinx_AFx_BIT(GPIOF,7,0)}I2Cx_PinSDA_Enum;/*define I2Cx SCL Pin enum*/typedef enum{ //define I2C0 I2C0_SCL_GPIOy1=I2Cx_Pinx_AFx_BIT(GPIOA,9,4), I2C0_SCL_GPIOy2=I2Cx_Pinx_AFx_BIT(GPIOB,6,1), I2C1_SCL_GPIOy3=I2Cx_Pinx_AFx_BIT(GPIOB,8,1), //define I2C1 I2C1_SCL_GPIOy4=I2Cx_Pinx_AFx_BIT(GPIOA,0,4), I2C1_SCL_GPIOy5=I2Cx_Pinx_AFx_BIT(GPIOB,10,1), I2C1_SCL_GPIOy6=I2Cx_Pinx_AFx_BIT(GPIOB,6,0)}I2Cx_PinSCL_Enum;/*define I2Cx address model*/typedef enum{ I2Cx_Address_7bit=I2C_ADDFORMAT_7BITS, I2Cx_Address_10bit=I2C_ADDFORMAT_10BITS}Address_Model_Enum;/*define I2Cx slaver address*/typedef enum{ Slaver_7Address=0x40,Slaver_10Address=0x230}Slaver_Address_Enum;/*define I2CX init param*/typedef struct {uint32_t Memory_address;I2Cx_PinSDA_Enum gpio_sdapin;I2Cx_PinSCL_Enum gpio_sclpin;rcu_periph_enum I2Cx_Periph;I2Cx_Speed_enum I2c_speed;Address_Model_Enum address_model;Send_Address_Enum address;Slaver_Address_Enum slaver_address;}Param_Typedef;/*I2C gpio init function*/void I2Cx_Init(Param_Typedef* i2c_init);/*I2C gpiopin enable*/void I2Cx_Pin_ClockEnable(I2Cx_PinSDA_Enum gpio_sdapin,I2Cx_PinSCL_Enum gpio_sclpin);/*I2C master send buffer 7 and 10 address*/void Master_SendData_address(uint8_t* SendBuffer,uint8_t DataNum,Param_Typedef *i2c_init);/*I2C master receive data 7 and 10 address*/void Master_ReceiveData(uint8_t* ReceiveBuffer,uint8_t DataNum,Param_Typedef *i2c_init);/*I2C 7 bit address prepare send*/void Send_7Prepare(Param_Typedef *i2c_init);/*I2C 10 bit address prepare send*/void Send_10Prepare(Param_Typedef *i2c_init);/*I2C 10 bit address prepare receive*/void Receive_10Prepare(Param_Typedef *i2c_init);/*Master receive 7 address prepare*/void Receive_7Prepare(Param_Typedef *i2c_init);#endif /* MAIN_H *///.c文件#include "gd32f3x0.h"#include #include "gd32f350r_eval.h"#include "main.h"#include "systick.h"#define I2C0_Measure//#define I2C1_Measure#define BufferNum 20uint8_t write_buffer[BufferNum]={0};//send data bufferuint8_t receive_buffer[BufferNum]={0};//receive data bufferParam_Typedef I2Cx_Param;/*define I2Cx Param struct array*/static Param_Typedef Para_Aarry[]={/*I2C0 param array*/{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,standard_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,standard_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,High_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,High_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,More_HighSpeed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},/*I2C1 param array*/{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,standard_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,standard_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,High_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,High_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,More_HighSpeed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},};/*testing sequence enum*/typedef enum{/*Measure I2C0*/I2C0_Seven_Address_standard=0,I2C0_Ten_Address_standard,I2C0_Seven_Address_high,I2C0_Ten_Address_high,I2C0_Seven_Address_more_high,/*Measure I2C1*/I2C1_Seven_Address_standard,I2C1_Ten_Address_standard,I2C1_Seven_Address_high,I2C1_Ten_Address_high,I2C1_Seven_Address_more_high}Test_Sequence_Enum;/*Configure Param of I2Cx Send data*/void Configure_I2CX_Send(Test_Sequence_Enum measure_sequence);/*Configure Param of I2Cx receive data*/void Configure_I2CX_Receive(Test_Sequence_Enum measure_sequence);/*I2Cx param init*/void Param_Init(Param_Typedef* i2c_param,Param_Typedef* Param_Array,Test_Sequence_Enum measure_sequence);/*! \brief main function \param[in] none \param[out] none \retval none*/int main(void){ uint8_t num=0; /*configure EVAL_COM1*/ gd_eval_com_init(EVAL_COM); systick_config(); for(num=0;num<BufferNum;num++){ write_buffer[num]=num; } #ifdef I2C0_Measure /*Test Sequence I2C0 send*/ Configure_I2CX_Send(I2C0_Seven_Address_standard); Configure_I2CX_Send(I2C0_Ten_Address_standard); Configure_I2CX_Send(I2C0_Seven_Address_high); Configure_I2CX_Send(I2C0_Ten_Address_high); Configure_I2CX_Send(I2C0_Seven_Address_more_high); /*Test Sequence I2C0 receive*/ Configure_I2CX_Receive(I2C0_Seven_Address_standard); Configure_I2CX_Receive(I2C0_Ten_Address_standard); Configure_I2CX_Receive(I2C0_Seven_Address_high); Configure_I2CX_Receive(I2C0_Ten_Address_high); Configure_I2CX_Receive(I2C0_Seven_Address_more_high); #elif defined I2C1_Measure /*Test Sequence I2C1 send*/ Configure_I2CX_Send(I2C1_Seven_Address_standard); Configure_I2CX_Send(I2C1_Ten_Address_standard); Configure_I2CX_Send(I2C1_Seven_Address_high); Configure_I2CX_Send(I2C1_Ten_Address_high); Configure_I2CX_Send(I2C1_Seven_Address_more_high); /*Test Sequence I2C1 receive*/ Configure_I2CX_Receive(I2C1_Seven_Address_standard); Configure_I2CX_Receive(I2C1_Ten_Address_standard); Configure_I2CX_Receive(I2C1_Seven_Address_high); Configure_I2CX_Receive(I2C1_Ten_Address_high); Configure_I2CX_Receive(I2C1_Seven_Address_more_high); #endif while(1){ }}/*! \brief Configure Param of I2Cx I2Cx Send data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Configure_I2CX_Send(Test_Sequence_Enum measure_sequence){switch(measure_sequence){case I2C0_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0 Seven Address standard send success\n"); break;case I2C0_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_standard send success\n"); break;case I2C0_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_high send success\n"); break;case I2C0_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high send success\n"); break;case I2C0_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_more_high send success\n"); break;case I2C1_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1 Seven Address standard send success\n"); break;case I2C1_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_standard send success\n"); break;case I2C1_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_high send success\n"); break;case I2C1_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high send success\n"); break;case I2C1_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_more_high send success\n"); break;default:break;}}/*! \brief Configure Param of receive data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Configure_I2CX_Receive(Test_Sequence_Enum measure_sequence){ switch(measure_sequence){case I2C0_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_standard receive data success!!\n"); break;case I2C0_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_standard receive data success!!\n"); break;case I2C0_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_high receive data success!!\n"); break;case I2C0_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high receive data success!!\n"); break;case I2C0_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high receive data success!!\n"); break;case I2C1_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_standard receive data success!!\n"); break;case I2C1_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_standard receive data success!!\n"); break;case I2C1_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_high receive data success!!\n"); break;case I2C1_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high receive data success!!\n"); break;case I2C1_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); delay_1ms(3000);//delay 3s wait slaver init success! Master_ReceiveData(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high receive data success!!\n"); break;default:break;}}/*! \brief Configure Param of I2Cx receive data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Param_Init(Param_Typedef* i2c_param,Param_Typedef* Param_Array,Test_Sequence_Enum measure_sequence){ i2c_param->Memory_address=Param_Array[measure_sequence].Memory_address; i2c_param->gpio_sclpin=Param_Array[measure_sequence].gpio_sclpin; i2c_param->gpio_sdapin=Param_Array[measure_sequence].gpio_sdapin; i2c_param->address=Param_Array[measure_sequence].address; i2c_param->address_model=Param_Array[measure_sequence].address_model; i2c_param->I2Cx_Periph=Param_Array[measure_sequence].I2Cx_Periph; i2c_param->I2c_speed=Param_Array[measure_sequence].I2c_speed; i2c_param->slaver_address=Param_Array[measure_sequence].slaver_address;}/*! \brief I2C init \param[in] I2Cx_PinSDA_Enum SDA pin I2Cx_PinSCL_Enum SCL pinrcu_periph_enum I2C periph I2Cx_Speed_enum check clock frequenceAddress_Model_Enum 7 or 10 address check Slaver_Address_Enum 7 or 10 address \param[out] none \retval none*/void I2Cx_Init(Param_Typedef *i2c_init){uint32_t gpiox_sda,pinx_sda,afx_sda,gpiox_scl,pinx_scl,afx_scl;I2Cx_Pin_ClockEnable(i2c_init->gpio_sdapin,i2c_init->gpio_sclpin);//SCL and SDA GPIO enable/*GPIO sda configure*/gpiox_sda=(uint32_t)((i2c_init->gpio_sdapin)& 0xffffff00);pinx_sda=(0x01<<((i2c_init->gpio_sdapin & 0xf0) >> 4));afx_sda=AF((i2c_init->gpio_sdapin & 0x0f));I2Cx_Pin_ClockEnable(i2c_init->gpio_sdapin,i2c_init->gpio_sclpin);gpio_af_set(gpiox_sda, afx_sda, pinx_sda);//IO口引脚复用功能gpio_mode_set(gpiox_sda, GPIO_MODE_AF, GPIO_PUPD_PULLUP,pinx_sda);//GPIO口、备用功能、端口上拉模式、具体引脚gpio_output_options_set(gpiox_sda, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,pinx_sda);//GPIO口、推挽输出及开漏输出、输出速率、具体引脚/*GPIO scl configure*/gpiox_scl=(uint32_t)((i2c_init->gpio_sclpin)& 0xffffff00);pinx_scl=(0x01<<((i2c_init->gpio_sclpin & 0xf0) >> 4));afx_scl=AF((i2c_init->gpio_sclpin & 0x0f));gpio_af_set(gpiox_scl, afx_scl,pinx_scl);//IO口引脚复用功能gpio_mode_set(gpiox_scl, GPIO_MODE_AF, GPIO_PUPD_PULLUP,pinx_scl);//GPIO口、备用功能、端口上拉模式、具体引脚/*--------------------------------I2C module initaial configure------------------------------------*//*enable I2C clock*/rcu_periph_clock_enable(i2c_init->I2Cx_Periph);//使能I2C时钟/*configure I2C clock*/ i2c_clock_config(i2c_init->Memory_address,i2c_init->I2c_speed,I2C_DTCY_2);//I2C的基地址、I2C数据传输速度、I2C的快速模式/*configure I2C address*/ i2c_mode_addr_config(i2c_init->Memory_address,I2C_I2CMODE_ENABLE,i2c_init->address_model,i2c_init->slaver_address);//I2C基地址、I2C模式、7位地址模式、I2C从机地址/*enable I2C0*/ i2c_enable(i2c_init->Memory_address);//I2C外设使能 /*enable acknowledge*/i2c_ack_config(i2c_init->Memory_address,I2C_ACK_ENABLE);//选择是否发送应答信号}/*! \brief I2C GPIO Clock enable \param[in] I2Cx_PinSDA_Enum SDA pin I2Cx_PinSCL_Enum SCL pin \param[out] none \retval none*/void I2Cx_Pin_ClockEnable(I2Cx_PinSDA_Enum gpio_sdapin,I2Cx_PinSCL_Enum gpio_sclpin){uint32_t gpiox_sda,gpiox_scl;gpiox_sda=(uint32_t)(gpio_sdapin & 0xffffff00);gpiox_scl=(uint32_t)(gpio_sclpin & 0xffffff00);/*SDA enable*/if(gpiox_sda==GPIOB){ rcu_periph_clock_enable(RCU_GPIOB);}else if(gpiox_sda==GPIOA){ rcu_periph_clock_enable(RCU_GPIOC);}else if(gpiox_sda==GPIOF){rcu_periph_clock_enable(RCU_GPIOF);}/*SCL enable*/if(gpiox_scl==GPIOB){ rcu_periph_clock_enable(RCU_GPIOB);}else if(gpiox_scl==GPIOA){ rcu_periph_clock_enable(RCU_GPIOA);}}/*! \brief Master send data 7 and 10 address \param[in] SendBuffer send array DataNum send data num \param[out] none \retval none*/void Master_SendData_address(uint8_t* SendBuffer,uint8_t DataNum,Param_Typedef *i2c_init){ uint8_t num;/*wait until I2C bus is idle*/while(i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_I2CBSY)){}/*send a start condition to I2C bus*/i2c_start_on_bus(i2c_init->Memory_address);//在I2C总线上产生一个开始信号/*wait until SBSEND bit is set judge start whether send*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_SBSEND)){}//I2C_STAT0(i2c_init->Memory_address);//read I2C_STAT0 to clear ADDSENDif(i2c_init->address_model==I2Cx_Address_7bit){ Send_7Prepare(i2c_init);}else if(i2c_init->address_model==I2Cx_Address_10bit){ Send_10Prepare(i2c_init);}/*wait until the transmit data buffer is empty */ while(SET != i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_TBE)){}for(num=0;num<DataNum;num++){ i2c_data_transmit(i2c_init->Memory_address,SendBuffer[num]);while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_BTC)){}} /*send a stop condition to I2C bus*/ i2c_stop_on_bus(i2c_init->Memory_address);//在总线上发送停止信号位 /*wait until the stop condition is finished*/ while(I2C_CTL0(i2c_init->Memory_address)&0x0200);//等待结束信号发送 //printf("master send data success");}/*! \brief Master receive data \param[in] ReceiveBuffer receive data array DataNum receive data num address slaver address \param[out] none \retval none*/void Master_ReceiveData(uint8_t* ReceiveBuffer,uint8_t DataNum,Param_Typedef *i2c_init){/*wait until I2C bus is idle*/while(i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_I2CBSY));/*send a start condition to I2C bus*/i2c_start_on_bus(i2c_init->Memory_address);//在I2C总线上产生一个开始信号/*wait until SBSEND bit is set judge start whether send*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_SBSEND));if(i2c_init->address==Send_7Address){ Receive_7Prepare(i2c_init);}else if(i2c_init->address==Send_10Address){ Receive_10Prepare(i2c_init);}if(DataNum==1){ /*disable acknowledge*/ i2c_ack_config(i2c_init->Memory_address,I2C_ACK_DISABLE);//选择是否发送应答信号 /*send a stop condition to I2C bus*/ i2c_stop_on_bus(i2c_init->Memory_address);//在总线上发送停止信号位 /*I2C_DATA is not empty*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_RBNE)); *ReceiveBuffer=i2c_data_receive(i2c_init->Memory_address);//read data from I2C_DATA } while(DataNum){ if(DataNum==2){ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_RBNE)); *ReceiveBuffer=i2c_data_receive(i2c_init->Memory_address);//read data from I2C_DATA DataNum-=1; ReceiveBuffer++; /*disable acknowledge*/ i2c_ack_config(i2c_init->Memory_address,I2C_ACK_DISABLE);//选择是否发送应答信号 /*send a stop condition to I2C bus*/ i2c_stop_on_bus(i2c_init->Memory_address);//在总线上发送停止信号位 } /*I2C_DATA is not empty*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_RBNE)); *ReceiveBuffer=i2c_data_receive(i2c_init->Memory_address);//read data from I2C_DATA DataNum-=1; ReceiveBuffer++; } /*wait until the stop condition is finished*/ while(I2C_CTL0(i2c_init->Memory_address)&0x0200);//判断stop结束位已经发送 /*enable acknowledge*/ i2c_ack_config(i2c_init->Memory_address,I2C_ACK_ENABLE);//软件发送应答信号使能 i2c_ackpos_config(i2c_init->Memory_address,I2C_ACKPOS_CURRENT);//ACKEN位决定对当前正在接收的字节是否发送ACK/NACK；PECTRANS位表明PEC 是否处于移位寄存器中//printf("master receive data success");}/*! \brief Master send 7 address prepare \param[in] none \param[out] none \retval none*/void Send_7Prepare(Param_Typedef *i2c_init){ /*send slave address to I2C bus*/ i2c_master_addressing(i2c_init->Memory_address,i2c_init->address,I2C_TRANSMITTER);//发送从机地址+写、清除SBSEND位、I2C设备发送方 /*wait until ADDSEND bit is set*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND)){ } /*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位}/*! \brief Master receive 7 address prepare \param[in] none \param[out] none \retval none*/void Receive_7Prepare(Param_Typedef *i2c_init){ /*send slave address to I2C bus */ i2c_master_addressing(i2c_init->Memory_address,i2c_init->address,I2C_RECEIVER);//发送从机地址+写、清除SBSEND位、I2C设备发送方 /* wait until ADDSEND bit is set */ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND)){ } /*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位}/*! \brief Master send 10 address prepare \param[in] none \param[out] none \retval none*/void Send_10Prepare(Param_Typedef *i2c_init){ uint32_t adrH10,adrL10; adrH10=(((i2c_init->address & 0x300)>>7)|0xf0);//10位地址头(高2位) adrL10=i2c_init->address & 0xff;//10位地址(低8位) /*send slave address adr10 to I2C bus */ i2c_master_addressing(i2c_init->Memory_address,(uint8_t)adrH10, I2C_TRANSMITTER); /* wait until ADDSEND bit is set */ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADD10SEND)); i2c_data_transmit(i2c_init->Memory_address,adrL10); /*wait until ADDSEND bit is set*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND)); /*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位}/*! \brief Master receive 10 address prepare \param[in] none \param[out] none \retval none*/void Receive_10Prepare(Param_Typedef *i2c_init){ uint32_t adrH10,adrL10; adrH10=(((i2c_init->address & 0x300)>>7)|0xf0);//10位地址头(高2位)adrL10=i2c_init->address & 0xff;//10位地址(低8位)/*send slave address to I2C bus*/ i2c_master_addressing(i2c_init->Memory_address,(uint8_t)adrH10, I2C_TRANSMITTER);//发送从机10地址头+写、清除SBSEND位、I2C设备发送方/*wait until ADDSEND bit is set*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADD10SEND));i2c_data_transmit(i2c_init->Memory_address,adrL10);/* wait until ADDSEND bit is set */ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND));/*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位 /*send a start condition to I2C bus*/i2c_start_on_bus(i2c_init->Memory_address);//在I2C总线上产生一个开始信号/*wait until SBSEND bit is set judge start whether send*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_SBSEND));i2c_master_addressing(i2c_init->Memory_address,(uint8_t)adrH10,I2C_RECEIVER); while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND));//等待ADDSEND位置1 硬件置1/*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位}/* retarget the C library printf function to the USART */int fputc(int ch, FILE *f){ usart_data_transmit(EVAL_COM, (uint8_t)ch); while(RESET == usart_flag_get(EVAL_COM, USART_FLAG_TBE)); return ch;}/*! \brief this function handles SysTick exception \param[in] none \param[out] none \retval none*/void SysTick_Handler(void){ delay_decrement();}上述程序实现了主机发送和接收，速率100k/400k/1M，发送从机地址10bit、7bit，程序方便移植，只需将对应的.c和.h添加到工程中即可。当I2C的通信速率为1M时，需配置I2C模块所挂载的pclk时钟为3的整数倍或者25的整数倍，否则主机的SCL实际的时钟会有一定的误差，大于或者小于1M，大于1M可能导致通信失败（GD mcu官方手册有提到）。I2C总线空闲时，默认为高电平，因为GPIO口内部自带的上拉驱动能力不够，配置为开漏输出，需外接上拉电阻，GPIO的输出速率要选择最大（代码中选择的是50M)增加GPIO口输出能力，否则通过示波器查看发现SCL时钟波形不是正规的波形，也可能造成通信失败。不同GPIO口输出速率下，SCL时钟输出波形如下图所示。
1.4 从机发送和接收（速率100k\400k\1M，地址10bit or 7bit)
I2C的从机的通信时钟由主机提供，故不需要配置时钟，I2C初始化后默认为从机模式，发送start信号后，由从机模式转换为主机模式。
#include "gd32f3x0.h"#include #include "gd32f350r_eval.h"#include "main.h"#include "systick.h"#define I2C0_Measure//#define I2C1_Measure#define BufferNum 20uint8_t write_buffer[BufferNum]={0};//send data bufferuint8_t receive_buffer[BufferNum]={0};//receive data bufferParam_Typedef I2Cx_Param;/*define I2Cx Param struct array*/static Param_Typedef Para_Aarry[]={/*I2C0 param array*/{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,standard_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,standard_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,High_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,High_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C0,I2C0_SDA_GPIOx2,I2C0_SCL_GPIOy2,RCU_I2C0,More_HighSpeed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},/*I2C1 param array*/{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,standard_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,standard_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,High_speed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,High_speed,I2Cx_Address_10bit,Send_10Address,Slaver_10Address},{I2C1,I2C1_SDA_GPIOx5,I2C1_SCL_GPIOy5,RCU_I2C1,More_HighSpeed,I2Cx_Address_7bit,Send_7Address,Slaver_7Address},};/*testing sequence enum*/typedef enum{/*Measure I2C0*/I2C0_Seven_Address_standard=0,I2C0_Ten_Address_standard,I2C0_Seven_Address_high,I2C0_Ten_Address_high,I2C0_Seven_Address_more_high,/*Measure I2C1*/I2C1_Seven_Address_standard,I2C1_Ten_Address_standard,I2C1_Seven_Address_high,I2C1_Ten_Address_high,I2C1_Seven_Address_more_high}Test_Sequence_Enum;/*Configure Param of I2Cx Send data*/void Configure_I2CX_Send(Test_Sequence_Enum measure_sequence);/*Configure Param of I2Cx receive data*/void Configure_I2CX_Receive(Test_Sequence_Enum measure_sequence);/*I2Cx param init*/void Param_Init(Param_Typedef* i2c_param,Param_Typedef* Param_Array,Test_Sequence_Enum measure_sequence);/*! \brief main function \param[in] none \param[out] none \retval none*/int main(void){ uint8_t num=0; for(num=0;num<BufferNum;num++){ write_buffer[num]=num; } //printf("I2C slaver measuring\n"); #ifdef I2C0_Measure /*Test Sequence I2C0 receive*/ Configure_I2CX_Receive(I2C0_Seven_Address_standard); Configure_I2CX_Receive(I2C0_Ten_Address_standard); Configure_I2CX_Receive(I2C0_Seven_Address_high); Configure_I2CX_Receive(I2C0_Ten_Address_high); Configure_I2CX_Receive(I2C0_Seven_Address_more_high); /*Test Sequence I2C0 send*/ Configure_I2CX_Send(I2C0_Seven_Address_standard); Configure_I2CX_Send(I2C0_Ten_Address_standard); Configure_I2CX_Send(I2C0_Seven_Address_high); Configure_I2CX_Send(I2C0_Ten_Address_high); Configure_I2CX_Send(I2C0_Seven_Address_more_high); #elif defined I2C1_Measure /*Test Sequence I2C1 receive*/ Configure_I2CX_Receive(I2C1_Seven_Address_standard); Configure_I2CX_Receive(I2C1_Ten_Address_standard); Configure_I2CX_Receive(I2C1_Seven_Address_high); Configure_I2CX_Receive(I2C1_Ten_Address_high); Configure_I2CX_Receive(I2C1_Seven_Address_more_high); /*Test Sequence I2C1 send*/ Configure_I2CX_Send(I2C1_Seven_Address_standard); Configure_I2CX_Send(I2C1_Ten_Address_standard); Configure_I2CX_Send(I2C1_Seven_Address_high); Configure_I2CX_Send(I2C1_Ten_Address_high); Configure_I2CX_Send(I2C1_Seven_Address_more_high); #endif while(1){ }}/*! \brief Configure Param of I2Cx I2Cx Send data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Configure_I2CX_Send(Test_Sequence_Enum measure_sequence){switch(measure_sequence){case I2C0_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0 Seven Address standard send success\n"); break;case I2C0_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_standard send success\n"); break;case I2C0_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_high send success\n"); break;case I2C0_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high send success\n"); break;case I2C0_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_more_high send success\n"); break;case I2C1_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1 Seven Address standard send success\n"); break;case I2C1_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_standard send success\n"); break;case I2C1_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_high send success\n"); break;case I2C1_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high send success\n"); break;case I2C1_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); Slaver_SendData_address(write_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_more_high send success\n"); break;default:break;}}/*! \brief Configure Param of receive data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Configure_I2CX_Receive(Test_Sequence_Enum measure_sequence){ switch(measure_sequence){case I2C0_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_standard receive data success!!\n"); break;case I2C0_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_standard receive data success!!\n"); break;case I2C0_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Seven_Address_high receive data success!!\n"); break;case I2C0_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Ten_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high receive data success!!\n"); break;case I2C0_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C0_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C0_Ten_Address_high receive data success!!\n"); break;case I2C1_Seven_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_standard receive data success!!\n"); break;case I2C1_Ten_Address_standard: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_standard); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_standard receive data success!!\n"); break;case I2C1_Seven_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Seven_Address_high receive data success!!\n"); break;case I2C1_Ten_Address_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Ten_Address_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high receive data success!!\n"); break;case I2C1_Seven_Address_more_high: Param_Init(&I2Cx_Param,Para_Aarry,I2C1_Seven_Address_more_high); I2Cx_Init(&I2Cx_Param); Slaver_ReceiveData_address(receive_buffer,BufferNum,&I2Cx_Param); printf("I2C1_Ten_Address_high receive data success!!\n"); break;default:break;}}/*! \brief Configure Param of I2Cx receive data \param[in] Test_Sequence_Enum measure_sequence //test sequence \param[out] none \retval none*/void Param_Init(Param_Typedef* i2c_param,Param_Typedef* Param_Array,Test_Sequence_Enum measure_sequence){ i2c_param->Memory_address=Param_Array[measure_sequence].Memory_address; i2c_param->gpio_sclpin=Param_Array[measure_sequence].gpio_sclpin; i2c_param->gpio_sdapin=Param_Array[measure_sequence].gpio_sdapin; i2c_param->address=Param_Array[measure_sequence].address; i2c_param->address_model=Param_Array[measure_sequence].address_model; i2c_param->I2Cx_Periph=Param_Array[measure_sequence].I2Cx_Periph; i2c_param->I2c_speed=Param_Array[measure_sequence].I2c_speed; i2c_param->slaver_address=Param_Array[measure_sequence].slaver_address;}/*! \brief I2C init \param[in] I2Cx_PinSDA_Enum SDA pin I2Cx_PinSCL_Enum SCL pinrcu_periph_enum I2C periph I2Cx_Speed_enum check clock frequenceAddress_Model_Enum 7 or 10 address check Slaver_Address_Enum 7 or 10 address \param[out] none \retval none*/void I2Cx_Init(Param_Typedef *i2c_init){uint32_t gpiox_sda,pinx_sda,afx_sda,gpiox_scl,pinx_scl,afx_scl;I2Cx_Pin_ClockEnable(i2c_init->gpio_sdapin,i2c_init->gpio_sclpin);//SCL and SDA GPIO enable/*GPIO sda configure*/gpiox_sda=(uint32_t)((i2c_init->gpio_sdapin)& 0xffffff00);pinx_sda=(0x01<<((i2c_init->gpio_sdapin & 0xf0) >> 4));afx_sda=AF((i2c_init->gpio_sdapin & 0x0f));I2Cx_Pin_ClockEnable(i2c_init->gpio_sdapin,i2c_init->gpio_sclpin);gpio_af_set(gpiox_sda, afx_sda, pinx_sda);//IO口引脚复用功能gpio_mode_set(gpiox_sda, GPIO_MODE_AF, GPIO_PUPD_PULLUP,pinx_sda);//GPIO口、备用功能、端口上拉模式、具体引脚gpio_output_options_set(gpiox_sda, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,pinx_sda);//GPIO口、推挽输出及开漏输出、输出速率、具体引脚/*GPIO scl configure*/gpiox_scl=(uint32_t)((i2c_init->gpio_sclpin)& 0xffffff00);pinx_scl=(0x01<<((i2c_init->gpio_sclpin & 0xf0) >> 4));afx_scl=AF((i2c_init->gpio_sclpin & 0x0f));gpio_af_set(gpiox_scl, afx_scl,pinx_scl);//IO口引脚复用功能gpio_mode_set(gpiox_scl, GPIO_MODE_AF, GPIO_PUPD_PULLUP,pinx_scl);//GPIO口、备用功能、端口上拉模式、具体引脚gpio_output_options_set(gpiox_scl, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,pinx_scl);//GPIO口、推挽输出及开漏输出、输出速率、具体引脚/*--------------------------------I2C module initaial configure------------------------------------*//*enable I2C clock*/rcu_periph_clock_enable(i2c_init->I2Cx_Periph);//使能I2C时钟/*configure I2C clock*/ i2c_clock_config(i2c_init->Memory_address,i2c_init->I2c_speed,I2C_DTCY_2);//I2C的基地址、I2C数据传输速度、I2C的快速模式/*configure I2C address*/ i2c_mode_addr_config(i2c_init->Memory_address,I2C_I2CMODE_ENABLE,i2c_init->address_model,i2c_init->slaver_address);//I2C基地址、I2C模式、7位地址模式、I2C从机地址/*enable I2C0*/ i2c_enable(i2c_init->Memory_address);//I2C外设使能 /*enable acknowledge*/i2c_ack_config(i2c_init->Memory_address,I2C_ACK_ENABLE);//选择是否发送应答信号}/*! \brief I2C GPIO Clock enable \param[in] I2Cx_PinSDA_Enum SDA pin I2Cx_PinSCL_Enum SCL pin \param[out] none \retval none*/void I2Cx_Pin_ClockEnable(I2Cx_PinSDA_Enum gpio_sdapin,I2Cx_PinSCL_Enum gpio_sclpin){uint32_t gpiox_sda,gpiox_scl;gpiox_sda=(uint32_t)(gpio_sdapin & 0xffffff00);gpiox_scl=(uint32_t)(gpio_sclpin & 0xffffff00);/*SDA enable*/if(gpiox_sda==GPIOB){ rcu_periph_clock_enable(RCU_GPIOB);}else if(gpiox_sda==GPIOA){ rcu_periph_clock_enable(RCU_GPIOC);}else if(gpiox_sda==GPIOF){rcu_periph_clock_enable(RCU_GPIOF);}/*SCL enable*/if(gpiox_scl==GPIOB){ rcu_periph_clock_enable(RCU_GPIOB);}else if(gpiox_scl==GPIOA){ rcu_periph_clock_enable(RCU_GPIOA);}}/*! \brief Slaver receive data \param[in] uint8_t* SendBuffer //receive buffer uint8_t DataNum //receive data num Param_Typedef *i2c_init //define I2CX init param \param[out] none \retval none*/void Slaver_ReceiveData_address(uint8_t* ReceiveBuffer,uint8_t DataNum,Param_Typedef *i2c_init){/*waiting I2C_FLAG_ADDSEND is set 1*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND)); /*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位 while(DataNum){/*I2C_DATA is not empty*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_RBNE));*ReceiveBuffer=i2c_data_receive(i2c_init->Memory_address);//read data from I2C_DATAReceiveBuffer+=1;DataNum-=1;}while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_STPDET));/*clear STPDET flag*/I2C_STAT0(i2c_init->Memory_address);I2C_CTL0(i2c_init->Memory_address)=0x0000;//printf("slaver receive data success!!\n");}/*! \brief I2C slaver send buffer 7 and 10 address \param[in] uint8_t* SendBuffer //receive buffer uint8_t DataNum //receive data num Param_Typedef *i2c_init //define I2CX init param \param[out] none \retval none*/void Slaver_SendData_address(uint8_t* SendBuffer,uint8_t DataNum,Param_Typedef *i2c_init){uint8_t num;/*waiting I2C_FLAG_ADDSEND is set 1*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND)); /*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位if(i2c_init->address_model==I2Cx_Address_10bit){ /*wait until ADDSEND bit is set*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_ADDSEND));/*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_ADDSEND);//清除ADDSEND位}/*wait until the transmit data buffer is empty*/ while(SET != i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_TBE));//send one byte to I2C BUSi2c_data_transmit(i2c_init->Memory_address,*SendBuffer);SendBuffer+=1;while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_BTC));//send two byte to I2C BUSi2c_data_transmit(i2c_init->Memory_address,*SendBuffer);SendBuffer+=1;for(num=0;num<(DataNum-2);num++){ /*I2C_DATA is not empty*/ while(!i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_BTC));i2c_data_transmit(i2c_init->Memory_address,*SendBuffer); SendBuffer+=1;}/*wait until the transmit data buffer is empty*/ while(SET != i2c_flag_get(i2c_init->Memory_address,I2C_FLAG_AERR));//clear I2C AERR flagi2c_flag_clear(i2c_init->Memory_address,I2C_FLAG_AERR);}/* retarget the C library printf function to the USART */int fputc(int ch, FILE *f){ usart_data_transmit(EVAL_COM, (uint8_t)ch); while(RESET == usart_flag_get(EVAL_COM, USART_FLAG_TBE)); return ch;}/*! \brief this function handles SysTick exception \param[in] none \param[out] none \retval none*/void SysTick_Handler(void){ delay_decrement();}以上从机接收和发送代码和主机一一对应，两者可作为测试使用。I2C从机支持双地址、10bit地址和广播地址模式（0x00)。双地址模式：I2C从机设备可对两个地址响应。广播地址模式：所有I2C从机设备默认的响应地址。
//双地址模式 i2c_dualaddr_enable(I2C0,0x44);//广播地址 i2c_slave_response_to_gcall_config(I2C0, I2C_GCEN_ENABLE);1.5 主机中断接收发送程序
//主机中断发送int main(void){ uint8_t num=0; /*configure EVAL_COM1*/ gd_eval_com_init(EVAL_COM); systick_config(); for(num=0;num<BufferNum;num++){ write_buffer[num]=num; } printf("I2C master send by interrupt measuring!!!"); Param_Init(&I2Cx_Param,Para_Aarry,I2C_Measuring); I2Cx_Init(&I2Cx_Param); nvic_irq_enable(I2Cx_EV_IRQn,0,0);/*!< I2C0 event interrupt priority and enable*/ nvic_irq_enable(I2Cx_ER_IRQn,0,1);/*!< I2C0 erro interrupt priority and enable*/ i2c_interrupt_enable(I2C_x,I2C_INT_ERR);//error interrupt enable i2c_interrupt_enable(I2C_x,I2C_INT_EV);//event interrupt enable i2c_interrupt_enable(I2C_x,I2C_INT_BUF);//buffer interrupt enable delay_1ms(3000); /*wait until I2C bus is idle*/ while(i2c_flag_get(I2C_x,I2C_FLAG_I2CBSY)); /*send a start condition to I2C bus*/i2c_start_on_bus(I2C_x);//在I2C总线上产生一个开始信号 while(!Send_InterruptFlag);/*wait until the stop condition is finished*/ while(I2C_CTL0(I2C_x)&0x0200);//等待结束信号发送 printf("I2C0 master interrupt send success!!"); while(1){ }}/*! \brief this function handles I2C0 Event \param[in] none \param[out] none \retval none*/void I2C0_EV_IRQHandler(void){if(i2c_flag_get(I2C_x,I2C_FLAG_SBSEND)){ I2C_STAT0(I2C_x); /*send slave address to I2C bus */ i2c_master_addressing(I2C_x,0x42,I2C_TRANSMITTER);//发送从机地址+写、清除SBSEND位、I2C设备发送方}else if(i2c_flag_get(I2C_x,I2C_FLAG_ADDSEND)){ i2c_flag_clear(I2C_x,I2C_FLAG_ADDSEND);//清除ADDSEND位}else if(i2c_flag_get(I2C_x,I2C_FLAG_TBE)){if(Data<20){ i2c_data_transmit(I2C_x,write_buffer[Data]); Data+=1;}else{ i2c_stop_on_bus(I2C_x);//在总线上发送停止信号位Send_InterruptFlag=1;i2c_interrupt_disable(I2C_x,I2C_INT_ERR);//error interrupt enable i2c_interrupt_disable(I2C_x,I2C_INT_EV);//event interrupt enable i2c_interrupt_disable(I2C_x,I2C_INT_BUF);//buffer interrupt enable}}}/*! \brief this function handles I2C0 Error \param[in] none \param[out] none \retval none*/void I2C0_ER_IRQHandler(void){//SMBus Alert statusif(i2c_flag_get(I2C_x,I2C_FLAG_SMBALT)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBALT);}//timeout signal in SMBus modeif(i2c_flag_get(I2C_x,I2C_FLAG_SMBTO)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBTO);}//PEC error when receiving dataif(i2c_flag_get(I2C_x,I2C_FLAG_PECERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_PECERR);}//over-run or under-run situation occurs in slave modeif(i2c_flag_get(I2C_x,I2C_FLAG_OUERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_OUERR);}//acknowledge errorif(i2c_flag_get(I2C_x,I2C_FLAG_AERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_AERR);}//arbitration lost in master modeif(i2c_flag_get(I2C_x,I2C_FLAG_LOSTARB)){ i2c_flag_clear(I2C_x,I2C_FLAG_LOSTARB);}//a bus error if(i2c_flag_get(I2C_x,I2C_FLAG_BERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_BERR);}}//主机接收中断/*! \brief this function handles I2C0 Event \param[in] none \param[out] none \retval none*/void I2C0_EV_IRQHandler(void){if(i2c_flag_get(I2C_x,I2C_FLAG_SBSEND)){ I2C_STAT0(I2C_x); /*send slave address to I2C bus */ i2c_master_addressing(I2C_x,0x42,I2C_RECEIVER);//发送从机地址+写、清除SBSEND位、I2C设备发送方}if(i2c_flag_get(I2C_x,I2C_FLAG_ADDSEND)){ i2c_flag_clear(I2C_x,I2C_FLAG_ADDSEND);//清除ADDSEND位}if(i2c_flag_get(I2C_x,I2C_FLAG_RBNE)){ if(Data==18){ receive_buffer[Data]=i2c_data_receive(I2C_x); Data+=1; /*disable acknowledge*/ i2c_ack_config(I2C_x,I2C_ACK_DISABLE);//选择是否发送应答信号 i2c_stop_on_bus(I2C_x);//在总线上发送停止信号位 }else if(Data<18){ receive_buffer[Data]=i2c_data_receive(I2C_x); Data+=1; }else if(Data==19) { receive_buffer[Data]=i2c_data_receive(I2C_x);Receive_InterruptFlag=1;i2c_interrupt_disable(I2C_x,I2C_INT_ERR);//error interrupt enable i2c_interrupt_disable(I2C_x,I2C_INT_EV);//event interrupt enable i2c_interrupt_disable(I2C_x,I2C_INT_BUF);//buffer interrupt enable } }}/*! \brief this function handles I2C0 Error \param[in] none \param[out] none \retval none*/void I2C0_ER_IRQHandle(void){//SMBus Alert statusif(i2c_flag_get(I2C_x,I2C_FLAG_SMBALT)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBALT);}//timeout signal in SMBus modeif(i2c_flag_get(I2C_x,I2C_FLAG_SMBTO)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBTO);}//PEC error when receiving dataif(i2c_flag_get(I2C_x,I2C_FLAG_PECERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_PECERR);}//over-run or under-run situation occurs in slave modeif(i2c_flag_get(I2C_x,I2C_FLAG_OUERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_OUERR);}//acknowledge errorif(i2c_flag_get(I2C_x,I2C_FLAG_AERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_AERR);}//arbitration lost in master modeif(i2c_flag_get(I2C_x,I2C_FLAG_LOSTARB)){ i2c_flag_clear(I2C_x,I2C_FLAG_LOSTARB);}//a bus error if(i2c_flag_get(I2C_x,I2C_FLAG_BERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_BERR);}}如果项目程序有多个中断，尽可能将I2C主机接收的中断优先级设为最高，否则会存在主机多接收一个数据，原因：当主机接收一个数据时，RBNE置1，在未读取DATA寄存器中的数据时，被更高的优先级任务打断，I2C总线上又接收一个数据到移位寄存器，此时BTC标志位置1。当中断恢复时，主机读取DATA寄存器中的数据。因为此时BTC已经置1，BTC清除的条件是需先读state状态寄存器，再读DATA寄存器，此时读DATA寄存器，无法清除BTC，使移位寄存器中的数据无法移到数据寄存器，I2C总线SCL被拉低，已阻止接收下一个数据，此时I2C还认为接收两个数据，会再次进中断读取DATA寄存器，BTC清零，移位寄存器数据移到Data寄存器，再次读取下一个数据，会造成接收的数据中有两个前后重复的数据。
1.6 从机中断接收和发送
//从机中断接收/*! \brief this function handles I2C0 Event \param[in] none \param[out] none \retval none*/void I2C0_EV_IRQHandler(void){if(i2c_interrupt_flag_get(I2C_x,I2C_INT_FLAG_ADDSEND)){/*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(I2C_x,I2C_FLAG_ADDSEND);//清除ADDSEND位}else if(i2c_interrupt_flag_get(I2C_x,I2C_INT_FLAG_TBE)){ if(Data<20){i2c_data_transmit(I2C_x,writer_buffer[Data]);Data+=1; }else{ Send_InterruptFlag=1; i2c_interrupt_disable(I2C_x,I2C_INT_ERR); i2c_interrupt_disable(I2C_x,I2C_INT_EV); i2c_interrupt_disable(I2C_x,I2C_INT_BUF); } }}/*! \brief this function handles I2C0 Error \param[in] none \param[out] none \retval none*/void I2C0_ER_IRQHandle(void){//SMBus Alert statusif(i2c_flag_get(I2C_x,I2C_FLAG_SMBALT)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBALT);}//timeout signal in SMBus modeif(i2c_flag_get(I2C_x,I2C_FLAG_SMBTO)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBTO);}//PEC error when receiving dataif(i2c_flag_get(I2C_x,I2C_FLAG_PECERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_PECERR);}//over-run or under-run situation occurs in slave modeif(i2c_flag_get(I2C_x,I2C_FLAG_OUERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_OUERR);}//acknowledge errorif(i2c_flag_get(I2C_x,I2C_FLAG_AERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_AERR);}//arbitration lost in master modeif(i2c_flag_get(I2C_x,I2C_FLAG_LOSTARB)){ i2c_flag_clear(I2C_x,I2C_FLAG_LOSTARB);}//a bus error if(i2c_flag_get(I2C_x,I2C_FLAG_BERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_BERR);}}//从机中断发送/*! \brief this function handles I2C0 Event \param[in] none \param[out] none \retval none*/void I2C0_EV_IRQHandler(void){if(i2c_interrupt_flag_get(I2C_x,I2C_INT_FLAG_ADDSEND)){/*read I2C_STAT0 and then read I2C_STAT1 to clear ADDSEND*/ i2c_flag_clear(I2C_x,I2C_FLAG_ADDSEND);//清除ADDSEND位}else if(i2c_interrupt_flag_get(I2C_x,I2C_INT_FLAG_TBE)){ if(Data<20){i2c_data_transmit(I2C_x,writer_buffer[Data]);Data+=1; }else{ Send_InterruptFlag=1; i2c_interrupt_disable(I2C_x,I2C_INT_ERR); i2c_interrupt_disable(I2C_x,I2C_INT_EV); i2c_interrupt_disable(I2C_x,I2C_INT_BUF); } }}/*! \brief this function handles I2C0 Error \param[in] none \param[out] none \retval none*/void I2C0_ER_IRQHandle(void){//SMBus Alert statusif(i2c_flag_get(I2C_x,I2C_FLAG_SMBALT)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBALT);}//timeout signal in SMBus modeif(i2c_flag_get(I2C_x,I2C_FLAG_SMBTO)){ i2c_flag_clear(I2C_x,I2C_FLAG_SMBTO);}//PEC error when receiving dataif(i2c_flag_get(I2C_x,I2C_FLAG_PECERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_PECERR);}//over-run or under-run situation occurs in slave modeif(i2c_flag_get(I2C_x,I2C_FLAG_OUERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_OUERR);}//acknowledge errorif(i2c_flag_get(I2C_x,I2C_FLAG_AERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_AERR);}//arbitration lost in master modeif(i2c_flag_get(I2C_x,I2C_FLAG_LOSTARB)){ i2c_flag_clear(I2C_x,I2C_FLAG_LOSTARB);}//a bus error if(i2c_flag_get(I2C_x,I2C_FLAG_BERR)){ i2c_flag_clear(I2C_x,I2C_FLAG_BERR);}}主机发送每一个byte数据时，从机都需发送ACK信号，而从机发送数据时，当主机接收到最后一个字节的数据时，给从机发NACK信号，从机接收到NACK信号后，就知道主机要结束通信了。从机SCL拉低功能作用是：从机在接收数据时，由于需要处理其他事情，比如打印一些调试信息，可能没有及时读取DATA寄存器中的数据，这时从机会拉低SCL时钟线已阻止主机发送下一个字节数据，也就是再告诉主机“我正在忙啦！您稍等片刻”，I2C中对这个拉低时间没有具体要求，但是在SMBUS中，对SCL拉低的时间规定为25ms，如果25ms从机还在拉低SCL硬件就会强制发送stop信号结束此次通信（也就是说主机的忍耐是有限度的哈！！）。
这篇就先写这么多，I2C硬件的其他主要特性及代码实现在后面介绍。