一、sgm58031模块

sgm58031的内部寄存器如下，我目前只需要单通道输入，所以只对配置寄存器Config_Reg写配置，转换寄存器Conversion_Reg读AD值。

//输入电压 = AINP-AINN	默认AINP=AIN0 AINN=AIN1
//输出数据速率 = 100HZ，即10ms更新一次数据
/* SGM58031内部寄存器地址 */
#define Conversion_Reg					0x00	//AD值转换寄存器，16bit数据，默认值0x0000，只读
#define Config_Reg						0x01	//配置寄存器,默认0x8583，可读可写
#define Lo_Thresh_Reg					0x02	//比较器阈值下限，默认0x8000
#define Hi_Thresh_Reg					0x03	//比较器阈值上限，默认0x7FFF
#define Config1_Reg						0x04	//扩展配置寄存器，默认0x0000
#define ChipID_Reg						0x05	//芯片ID，默认0x0080
#define GN_Trim1_Reg					0x06	//增益修正，默认0x03FA

其中配置寄存器主要设置输入差分信号的引脚，输入电压=AINp-AINn，设置PGA来选择合适的量程。

二、硬件I2C配置

头文件

/* ADC模块接I2C初始化底层接口定义 */  
#define I2C_ADC							I2C0
#define I2C_ADC_CLK						RCU_I2C0#define I2C_ADC_SCL						GPIO_PIN_1
#define I2C_ADC_SDA						GPIO_PIN_0#define I2C_ADC_GPIO_PORT				GPIOF
#define I2C_ADC_GPIO_CLK				RCU_GPIOF
#define	I2C_ADC_GPIO_AF					GPIO_AF_1#define I2C_ADC_ADDR_WRITE 				0x90		//adc模块的写地址
//#define I2C_ADC_ADDR_READ 				0x91		//adc模块的读地址#define I2C0_SPEED              		100000	//I2C0频率	/* 配置GPIO端口 */
void i2c_init(void);/* I2C写函数 */
void i2c_write(uint8_t reg_addr, uint16_t send_data);/* I2C读函数 */
uint16_t i2c_read_byte(uint8_t reg_addr);
#endif

I2C初始化

由于将ADDR引脚接GND，sgm58031的7bit地址为0x48再加上读写位，所以写地址：0x90 读地址：0x91

uint8_t sgm_addr = 0x90;/* I2C初始化配置 */
void i2c_init(void)
{/************I2C GPIO Config**************//* enable I2C port clock */rcu_periph_clock_enable(I2C_ADC_GPIO_CLK);/* connect PA9 to I2C_SCL */gpio_af_set(I2C_ADC_GPIO_PORT, I2C_ADC_GPIO_AF, I2C_ADC_SCL);/* connect PA10 to I2C_SDA */gpio_af_set(I2C_ADC_GPIO_PORT, I2C_ADC_GPIO_AF, I2C_ADC_SDA);/* configure GPIO pins of I2C */gpio_mode_set(I2C_ADC_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,I2C_ADC_SCL);gpio_output_options_set(I2C_ADC_GPIO_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,I2C_ADC_SCL);gpio_mode_set(I2C_ADC_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,I2C_ADC_SDA);gpio_output_options_set(I2C_ADC_GPIO_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ,I2C_ADC_SDA);/************I2C Config**************/	/* enable I2C clock */rcu_periph_clock_enable(I2C_ADC_CLK);/* I2C clock configure */i2c_clock_config(I2C_ADC, I2C0_SPEED, I2C_DTCY_2);/* I2C address configure */i2c_mode_addr_config(I2C_ADC, I2C_I2CMODE_ENABLE, I2C_ADDFORMAT_7BITS, sgm_addr);/* enable I2C */i2c_enable(I2C_ADC);/* enable acknowledge */i2c_ack_config(I2C_ADC, I2C_ACK_ENABLE);}

I2C写函数

由于我使用i2c_master_addressing(I2C_ADC, sgm_addr, I2C_TRANSMITTER)发送地址会卡死在后面的while里，因此替换为i2c_data_transmit(I2C_ADC, sgm_addr);运行正常。

/* I2C写函数 */
void i2c_write(uint8_t reg_addr, uint16_t send_data)
{uint8_t high_val=0x00;uint8_t low_val=0x00;low_val = send_data&0x00ff;				high_val = (send_data>>8)&0x00ff;/* wait until i2c bus is idle */while(i2c_flag_get(I2C_ADC, I2C_FLAG_I2CBSY));/* send a start condition to I2C bus */i2c_start_on_bus(I2C_ADC);/* wait until SBSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_SBSEND));    /* send slave address to I2C bus */
//	i2c_master_addressing(I2C_ADC, sgm_addr, I2C_TRANSMITTER);i2c_data_transmit(I2C_ADC, sgm_addr);/* wait until ADDSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_ADDSEND));/* clear ADDSEND bit */i2c_flag_clear(I2C_ADC, I2C_FLAG_ADDSEND);/* wait until the transmit data buffer is empty */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_TBE));/* 发送寄存器地址 */i2c_data_transmit(I2C_ADC, reg_addr);/* wait until the TBE bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_BTC));/* data transmission */i2c_data_transmit(I2C_ADC, high_val);//先发送高8位数据/* wait until the TBE bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_BTC));i2c_data_transmit(I2C_ADC, low_val);//再发送低8位数据/* wait until the TBE bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_BTC));/* send a stop condition to I2C bus */i2c_stop_on_bus(I2C_ADC);/* wait until stop condition generate */ while(I2C_CTL0(I2C_ADC)&0x0200);
}

I2C读函数

这里，我使用官方I2C例程发现，总是会卡死在等待I2C_FLAG_BTC发送完成的while循环里，各种查找网上参考，并未发现解决办法，所以我直接将出现等待发送完成的标志位判断语句屏蔽，结果就能正常读数据了。。。


/* I2C读函数 */
uint16_t i2c_read_byte(uint8_t reg_addr)
{uint8_t high_val=0x00;uint8_t low_val=0x00;uint16_t recv_val = 0x0000;/* wait until i2c bus is idle */while(i2c_flag_get(I2C_ADC, I2C_FLAG_I2CBSY));/* send a start condition to I2C bus */i2c_start_on_bus(I2C_ADC);/* wait until SBSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_SBSEND));    /* send slave address to I2C bus */
//	i2c_master_addressing(I2C_ADC, sgm_addr, I2C_TRANSMITTER);i2c_data_transmit(I2C_ADC, sgm_addr);/* wait until ADDSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_ADDSEND));/* clear ADDSEND bit */i2c_flag_clear(I2C_ADC, I2C_FLAG_ADDSEND);/* wait until the transmit data buffer is empty */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_TBE));/* 发送寄存器地址 */i2c_data_transmit(I2C_ADC, reg_addr);/* wait until the BTC bit is set */
//	while(!i2c_flag_get(I2C_ADC, I2C_FLAG_BTC));i2c_stop_on_bus(I2C_ADC);while(I2C_CTL0(I2C_ADC)&0x0200);i2c_start_on_bus(I2C_ADC);/* wait until SBSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_SBSEND));/* send slave address to I2C bus */
//	i2c_master_addressing(I2C_ADC, sgm_addr, I2C_RECEIVER);i2c_data_transmit(I2C_ADC, sgm_addr+1);/* wait until ADDSEND bit is set */while(!i2c_flag_get(I2C_ADC, I2C_FLAG_ADDSEND));/* clear the ADDSEND bit */i2c_flag_clear(I2C_ADC,I2C_FLAG_ADDSEND);/* wait until the RBNE bit is set	and clear it*/while(!i2c_flag_get(I2C_ADC, I2C_FLAG_RBNE));high_val = i2c_data_receive(I2C_ADC);while(!i2c_flag_get(I2C_ADC, I2C_FLAG_RBNE));i2c_ack_config(I2C_ADC, I2C_ACK_DISABLE);i2c_ackpos_config(I2C_ADC,I2C_ACKPOS_NEXT);
//	delay_1ms(1);low_val = i2c_data_receive(I2C_ADC);/* wait until the BTC bit is set */
//	while(!i2c_flag_get(I2C_ADC, I2C_FLAG_BTC));		/* send a stop condition to I2C bus */i2c_stop_on_bus(I2C_ADC);/* wait until stop condition generate */ while(I2C_CTL0(I2C_ADC)&0x0200);recv_val = (high_val<<8)|low_val;i2c_ack_config(I2C_ADC, I2C_ACK_ENABLE);return recv_val;
}

三、实际应用

写配置

这里设置主要有三点：
1.ADC输出数据频率：Config_Reg Bits[7:5]，默认为100，我设置为111，对应频率如下：
在这里插入图片描述
2.设置PGA为000，即FS=±6.144V 注意：若需测量3.3V以上的电压，需保证供电电压为5v！
3.设置输入电压的p脚为AIN0,n脚为GND，即输入电压V= AINp-GND = AINp