芯片介绍
SHT30是一款温湿度传感器,使用IIC通信接口。可根据命令设置其测量频率、测量时间;测量持续时间有三种可选(见芯片手册2.2):
HIGH:12.5ms;
medium:4.5ms;
low:2.5ms;
测量频率有五种可选:0.5次/秒、1次/秒、2次/秒、4次/秒、10次/秒。
如采样时间12.5ms,10次/秒的指令为:0x2737.例程如下:
static void start_measure(void)
{
const uint8_t iic_addr = 0x44 << 1;
const uint16_t cmd_meas_freq = 0x2737;
uint8_t cmd[2];
cmd[0] = cmd_meas_freq >> 8;
cmd[1] = cmd_meas_freq;
HAL_I2C_Master_Transmit(&hi2c1, iic_addr, cmd, 2, 100);
}
温湿度读取
在芯片手册4.6节有讲解如何读取芯片测量数据:
在芯片手册4.11节有讲解读出数据CRC校验方法:
例程如下:
uint8_t CRC8(uint8_t * p_buf, UINT16 num)
{
uint8_t result = 0xff;
uint8_t const ploynomial = 0x31;
for(uint8_t i = 0; i < num; i++)
{
result ^= p_buf[i];
for(uint8_t j = 0; j < 8; j++)
{
if(result&0x80)
{
result <<= 1;
result ^= ploynomial;
}
else
{
result <<= 1;
}
}
}
return result;
}
在芯片手册4.12节有讲解如何将芯片测量数据转换成我们想要的温湿度数据:
文章来源:https://www.toymoban.com/news/detail-428996.html
例程如下:文章来源地址https://www.toymoban.com/news/detail-428996.html
typedef struct
{
float temperature;
float humidity;
}Param;
uint8_t read_param(Param *param)
{
uint8_t data[6];
const uint8_t iic_addr = 0x44 << 1;
const uint16_t cmd_fetch_data = 0xE000;
uint8_t cmd[2];
cmd[0] = cmd_fetch_data >> 8;
cmd[1] = (uint8_t)cmd_fetch_data;
HAL_I2C_Master_Transmit(&hi2c1, iic_addr, cmd, 2, 100);
HAL_I2C_Master_Receive(&hi2c1, iic_addr, data, sizeof(data), 100);
if((CRC8(&data[0], 2) != data[2]) || (CRC8(&data[3], 2) != data[5]))
{
return FALSE;
}
uint8_t tmp = (data[0] << 8) + data[1];
param->temperature = ((float)(175*tmp)/65535) - 45;
tmp = (data[3] << 8) + data[4];
param->humidity = (float)(100*tmp)/65535;
return TRUE;
}
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