硬件IIC读取SHT20温湿度传感器

只看该作者 · 2023-3-30 15:55

已经收到板子许久了，最近在看他的一些外设，今天先分享下我测试的SHT20硬件IIC读取数据的测试。

/* PC6 - I2C1_SCL. */
gpio_init.Pins  = GPIO_PIN_6;
gpio_init.PinMode  = GPIO_PinMode_AF_OpenDrain;
gpio_init.Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &gpio_init);
GPIO_PinAFConf(GPIOC, gpio_init.Pins, GPIO_AF_4);

/* PC7 - I2C1_SDA. */
gpio_init.Pins  = GPIO_PIN_7;
gpio_init.PinMode  = GPIO_PinMode_AF_OpenDrain;
gpio_init.Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &gpio_init);
GPIO_PinAFConf(GPIOC, gpio_init.Pins, GPIO_AF_4);

首先我们需要对使用的IO进行初始化。这里IO是复用的。

实际是接入到我们的板子上的MPU6050和24c02设备上的，但是地址不同的，不会干扰的。

/* Initialize I2C */
void app_i2c_init(void)
{
/* Setup I2C initialization values. */
I2C_Master_Init_Type i2c_init;
i2c_init.ClockFreqHz = BOARD_I2C_FREQ;
i2c_init.BaudRate = I2C_BaudRate_100K;

/* Initialize I2C master. */
I2C_InitMaster(BOARD_I2C_PORT, &i2c_init);

/* The target device address needs to be configured before enabling. */
I2C_SetTargetAddr(BOARD_I2C_PORT, APP_I2C_TARGET_ADDR);

/* Enable I2C. */
I2C_Enable(BOARD_I2C_PORT, true);
}

Iic设备初始化，还是很简单的。这里的IIC波特率有两种可选择，我们选择100K的是没问题的。

/* Write data to target device, true to writing succeed, false to writing failed. */
bool app_i2c_write(uint8_t txlen, uint8_t *txbuf)
{
app_i2c_xfer.WaitTimes = APP_I2C_TIMEOUT_TIME;
app_i2c_xfer.TxBuf = txbuf;
app_i2c_xfer.TxLen = txlen;

I2C_Enable(BOARD_I2C_PORT, true);  /* Disable I2C to clear tx fifo, and enabled I2C to perform the write operation again. */
if ( false == I2C_MasterWriteBlocking(BOARD_I2C_PORT, &app_i2c_xfer) )
{
      return false;
}
else
{
      return true;
}
}

/* Read data to target device, true to reading succeed, false to reading failed. */
bool app_i2c_read(uint8_t rxlen, uint8_t *rxbuf)
{
app_i2c_xfer.WaitTimes = APP_I2C_TIMEOUT_TIME;
app_i2c_xfer.RxBuf = rxbuf;
app_i2c_xfer.RxLen = rxlen;

I2C_Enable(BOARD_I2C_PORT, true);  /* Disable I2C to clear tx fifo, and enabled I2C to perform the read operation again. */
if ( false == I2C_MasterReadBlocking(BOARD_I2C_PORT, &app_i2c_xfer) )
{
      return false;
}
else
{
      return true;
}
}

封装了两个函数，接收和发送，封装起来主要便于我们简化IIC的操作，我们只需要关系发送的数据多长，和数据其实地址。

#define SHT20_ADDRESS  0X40
#define SHT20_Measurement_RH_HM  0XE5
#define SHT20_Measurement_T_HM  0XE3
#define SHT20_Measurement_RH_NHM  0XF5
#define SHT20_Measurement_T_NHM  0XF3
#define SHT20_READ_REG  0XE7
#define SHT20_WRITE_REG  0XE6
#define SHT20_SOFT_RESET  0XFE

float TemValue,RhValue;

void SHT20_ReadValues(void)
{
  uint8_t tem[3],rh[3];
  uint16_t Tdata=0,RHdata=0;

  uint8_t cmd=SHT20_Measurement_T_HM;

if ( false == app_i2c_write(1, &cmd) )
{
      printf("I2C write failed.\r\n");
}

if ( false == app_i2c_read(3, tem) )  /* Received data successfully. */
{
      printf("I2C read failed.\r\n");
}
  delay_ms(100);
  cmd=SHT20_Measurement_RH_HM;

if ( false == app_i2c_write(1, &cmd) )
{
      printf("I2C write failed.\r\n");
}

if ( false == app_i2c_read(3, rh) )  /* Received data successfully. */
{
      printf("I2C read failed.\r\n");
}

  delay_ms(100);
  Tdata = tem[0];
  Tdata <<= 8;
  Tdata += tem[1] & 0xfe;

  RHdata = rh[0];
  RHdata <<= 8;
  RHdata += rh[1] & 0xfe;

  TemValue = Tdata * 175.72f / 65536 - 46.85f;
  RhValue = RHdata * 125.0f / 65536 - 6.0f;

printf("TemValue:%.2f℃\r\n",TemValue);
printf("RhValue:%.2f%%\r\n",RhValue);
}

void SHT20_SoftReset(void)
{
uint8_t cmd=0xfe;

if ( false == app_i2c_write(1, &cmd) )
{
      printf("I2C write failed.\r\n");
}
delay_ms(100);
}

之后再创建两个函数，一个是软件复位的，一个是读取的。也都比较的简单的。读取数据里面，数据没有进行校验了，直接就使用了。按照手册进行转换即可。