SHT3X – Sasapea's Lab

スイッチサイエンスからM5StickCが販売された。ディスプレーや各種センサー等が内蔵され何かと便利そうだったので購入。

なによりこのサイズ感がとても良いのだが何か実験するにも必要なものが一通り用意されており必要十分と言った感じがするし価格的にもお買い得感はあるのでこれはちょ～お勧めかもしれない。

とりあえず、製造元の製品ドキュメントを参考にArduinoをセットアップしサンプルを実行してみたところ、M5StickCライブラリがコンパイルエラーになりサンプルが何も実行できなかったりする．．．しょうがないのでライブラリのエラー箇所を適当に修正し、なんとかサンプルは実行できるようにはなったが、M5StickCライブラリ大丈夫なのか？とその品質を疑ってしまった。まぁ、ないよりはあったほうが良いことは確かなのではあるが．．．(-_-;)

次にSHT31センサーライブラリを探してみた。
GROVE - 温湿度センサ（SHT31） v1.0
GROVE – 温湿度センサ（SHT31） v1.0

GROVEや秋月電子のライブラリを見つけたが、とりあえずGROVEのSHT31ライブラリのコードを調べてみることに．．．
その結果、温度と湿度の両方を同時取得できるのにそれぞれ２回も通信しないといけないことや温湿度データ取得に50ms以上かかるというのは疑問符が残る。秋月電子のほうは温湿度データの同時取得に関しては問題ないが温湿度データ取得に300ms以上かかるのが痛い。

ということでGROVEのライブラリを参考に改良してみた。

改良点は、

・ArduinoのWireライブラリの互換ライブラリ対応
・I2C活線抜去対応
・計測待ち時間の除去。
・非力ＣＰＵ対応(データ型をfloat型からuint16_t型へ変更。小数部対応のためデータは16倍した値を返す)

などであるが、ほぼ全てを書き換えてしまったのでGROVEのものとは全く別物となってしまった感がある。

【サンプル・スケッチ実行中の様子】

【更新情報】
2020-02-20
・ライセンス変更。
・よりシンプルなコードに改良。
・begin()内で行っていたWireの初期化を削除。Wireの初期化はアプリ側で行うこと。

2019-06-25
・温度データ型が符号なしになっていた点を修正。
・begin()の引数にI2Cクロック指定を追加。規定値は400KHzとした。
・read()の呼び出しタイミングの制約を無くした。
・handle()呼び出しタイミングによっては温度データ取得に失敗する点を修正。

2019-06-20
handle()のデータ取得タイミングを改良。

2019-06-18
begin()の引数に温湿度データ取得間隔ms(省略値は1000ms)を追加。
getTempratureC()をtempratureC()に名前変更。
getTempratureF()をtempratureF()に名前変更。
getHumidity()をhumidity()に名前変更。
read(), error()メソッドを追加。
handle()をよりシンプルなコードにするため温湿度データ取得タイミングを変更。
非同期取得(測定待ち時間なし)はhandle()、即時取得(測定待ち時間有り)はread()を使う。

【サンプル・スケッチ】

#include <M5StickC.h>
#include "SHT3X.h"

#define M5_BUTTON_A M5_BUTTON_HOME
#define M5_BUTTON_B M5_BUTTON_RST

#define M5_FONT1 2
#define M5_FONT2 4
 
static SHT3X<>  sht3x;
static uint8_t contrast = 9;

static int16_t  temp_val = 0;
static uint16_t humi_val = 0;

void setup()
{
  //
  // Setup GPIO
  //
  pinMode(M5_BUTTON_A, INPUT);
  pinMode(M5_BUTTON_B, INPUT);
  pinMode(M5_LED, OUTPUT);
  digitalWrite(M5_LED, HIGH); // LOW: ON, HIGH: OFF
  //
  // Setup Display
  //
  M5.begin();
  M5.Axp.ScreenBreath(contrast);
  M5.Lcd.setRotation(1);
  M5.Lcd.setCursor(0, 0);
  M5.Lcd.setTextFont(M5_FONT1);
  M5.Lcd.println("  [SHT3X]");
  M5.Lcd.setTextFont(M5_FONT2);
  //
  // Setup SHT3X
  //
  Wire.begin();
  Wire.setClock(400000); // 400KHz
  sht3x.begin();
}

void loop()
{
  //
  // Handle SHT3X
  //
  switch (sht3x.handle())
  {
    case SHT3X_NO_DEVICE:
      temp_val = 0;
      humi_val = 0;
      break;
    case SHT3X_READY:
      temp_val = sht3x.temperatureC();
      humi_val = sht3x.humidity();
      digitalWrite(M5_LED, !digitalRead(M5_LED));
      break;
  }
  //
  // Display Temperature and Humidity
  //
  M5.Lcd.setCursor(0, 24);
  M5.Lcd.printf("  %2.2f C   ", temp_val / 16.0);
  M5.Lcd.setCursor(0, 50);
  M5.Lcd.printf("  %2.2f %%   ", humi_val / 16.0);
  //
  // Control LCD Contrast
  //
  if(digitalRead(M5_BUTTON_A) == LOW)
  {
    if(++contrast >= 16)
      contrast = 7;
    M5.Axp.ScreenBreath(contrast);
    while(digitalRead(M5_BUTTON_A) == LOW)
      continue;
  }
  delay(10);
}

#include <M5StickC.h>

#include "SHT3X.h"

#define M5_BUTTON_A M5_BUTTON_HOME

#define M5_BUTTON_B M5_BUTTON_RST

#define M5_FONT1 2

#define M5_FONT2 4

static SHT3X<> sht3x;

static uint8_t contrast = 9;

static int16_t temp_val = 0;

static uint16_t humi_val = 0;

void setup()

{

// Setup GPIO

pinMode(M5_BUTTON_A, INPUT);

pinMode(M5_BUTTON_B, INPUT);

pinMode(M5_LED, OUTPUT);

digitalWrite(M5_LED, HIGH); // LOW: ON, HIGH: OFF

// Setup Display

M5.begin();

M5.Axp.ScreenBreath(contrast);

M5.Lcd.setRotation(1);

M5.Lcd.setCursor(0, 0);

M5.Lcd.setTextFont(M5_FONT1);

M5.Lcd.println(" [SHT3X]");

M5.Lcd.setTextFont(M5_FONT2);

// Setup SHT3X

Wire.begin();

Wire.setClock(400000); // 400KHz

sht3x.begin();

}

void loop()

{

// Handle SHT3X

switch (sht3x.handle())

{

case SHT3X_NO_DEVICE:

temp_val = 0;

humi_val = 0;

break;

case SHT3X_READY:

temp_val = sht3x.temperatureC();

humi_val = sht3x.humidity();

digitalWrite(M5_LED, !digitalRead(M5_LED));

break;

}

// Display Temperature and Humidity

M5.Lcd.setCursor(0, 24);

M5.Lcd.printf(" %2.2f C ", temp_val / 16.0);

M5.Lcd.setCursor(0, 50);

M5.Lcd.printf(" %2.2f %% ", humi_val / 16.0);

// Control LCD Contrast

if(digitalRead(M5_BUTTON_A) == LOW)

{

if(++contrast >= 16)

contrast = 7;

M5.Axp.ScreenBreath(contrast);

while(digitalRead(M5_BUTTON_A) == LOW)

continue;

}

delay(10);

}

【SHT3Xライブラリ】

/*
  SHT3X.h - Temperatute and Humidity Library for Sensirion SHT3x(30/31/35)

  Copyright (c) 2020 Sasapea's Lab. All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA
*/
#ifndef _SHT3X_H
#define _SHT3X_H

#include <stdint.h>
#include <stdbool.h>

#define SHT3X_NO_DEVICE  0
#define SHT3X_IDLE       1
#define SHT3X_BUSY       2
#define SHT3X_READY      3

#define SHT3X_DEFAULT_ADDRESS  0x44
#define SHT3X_SINGLE_H_STRETCH 0x2C06
#define SHT3X_SINGLE_M_STRETCH 0x2C0D
#define SHT3X_SINGLE_L_STRETCH 0x2C10
#define SHT3X_SINGLE_H         0x2400
#define SHT3X_SINGLE_M         0x240B
#define SHT3X_SINGLE_L         0x2416
#define SHT3X_REPEAT_H_05MPS   0x2032
#define SHT3X_REPEAT_M_05MPS   0x2024
#define SHT3X_REPEAT_L_05MPS   0x202F
#define SHT3X_REPEAT_H_1MPS    0x2130
#define SHT3X_REPEAT_M_1MPS    0x2126
#define SHT3X_REPEAT_L_1MPS    0x212D
#define SHT3X_REPEAT_H_2MPS    0x2236
#define SHT3X_REPEAT_M_2MPS    0x2220
#define SHT3X_REPEAT_L_2MPS    0x222B
#define SHT3X_REPEAT_H_4MPS    0x2334
#define SHT3X_REPEAT_M_4MPS    0x2322
#define SHT3X_REPEAT_L_4MPS    0x2329
#define SHT3X_REPEAT_H_10MPS   0x2737
#define SHT3X_REPEAT_M_10MPS   0x2721
#define SHT3X_REPEAT_L_10MPS   0x272A
#define SHT3X_REPEAT_ART       0x2B32
#define SHT3X_REPEAT_STOP      0x3093
#define SHT3X_FETCH_DATA       0xE000
#define SHT3X_RESET            0x30A2
#define SHT3X_HEATER_ON        0x306D
#define SHT3X_HEATER_OFF       0x3066
#define SHT3X_STATUS_CLEAR     0x3041
#define SHT3X_STATUS_READ      0xF32D

#define SHT3X_RESET_TIME           ( 1 + 1)
#define SHT3X_MEASUREMENT_TIME     (15 + 1)
#define SHT3X_MEASUREMENT_INTERVAL 100
#define SHT3X_SAMPLING_PERIOD      1000

template<typename WIRE_T = TwoWire, WIRE_T& WIRE = Wire>
class SHT3X
{
  private:
    uint8_t  _address;
    uint8_t  _status;
    uint16_t _interval;
    uint16_t _start;
    int16_t  _temperature;
    uint16_t _humidity;
    uint8_t  _error;
    
    bool command(uint16_t cmd)
    {
      WIRE.beginTransmission(_address);
      WIRE.write(cmd >> 8);
      WIRE.write(cmd & 0xFF);
      return (_error = WIRE.endTransmission()) == 0;
    }

    uint8_t crc8(const uint8_t *data, int8_t len)
    {
      uint8_t crc = 0xFF;
      while (--len >= 0)
      {
        crc ^= *data++;
        for (int8_t i = 8; --i >= 0;)
          crc = (crc & 0x80) ? (crc << 1) ^ 0x31 : (crc << 1);
      }
      return crc; 
    }

    uint8_t fetch(void)
    {
      struct
      {
        struct
        {
          uint8_t high;
          uint8_t low;
        } temp;
        uint8_t temp_crc;
        struct
        {
          uint8_t high;
          uint8_t low;
        } humi;
        uint8_t humi_crc;
      } data;
      uint16_t temp, humi;

      _status = SHT3X_NO_DEVICE;
      _start  = (uint16_t)millis() - SHT3X_MEASUREMENT_TIME;
      if (WIRE.requestFrom(_address, sizeof(data)) != sizeof(data))
        return _status;
      for (uint8_t i = 0; i < sizeof(data); i++)
        ((uint8_t *)&data)[i] = WIRE.read();
      if (crc8((uint8_t *)&data.temp, sizeof(data.temp)) != data.temp_crc)
        return _status;
      if (crc8((uint8_t *)&data.humi, sizeof(data.humi)) != data.humi_crc)
        return _status;
      temp = ((uint16_t)data.temp.high << 8) | data.temp.low;
      humi = ((uint16_t)data.humi.high << 8) | data.humi.low;
      _temperature = ((uint32_t)temp * 175 * 16 / 65535) - (45 * 16);
      _humidity    = ((uint32_t)humi * 100 * 16 / 65535);
      _status = SHT3X_IDLE;
      return SHT3X_READY;
    }

    uint8_t measurement(void)
    {
      _status = command(SHT3X_SINGLE_H) ? SHT3X_BUSY : SHT3X_NO_DEVICE;
      _start  = (uint16_t)millis();
      return _status;
    }

    uint8_t reset(void)
    {
      _status = SHT3X_NO_DEVICE;
      if (command(SHT3X_RESET))
      {
        _status = SHT3X_IDLE;
        delay(SHT3X_RESET_TIME);
      }
      _start = (uint16_t)millis();
      return _status;
    }

  public:
    SHT3X(uint8_t addr = SHT3X_DEFAULT_ADDRESS)
    : _address(addr)
    , _status(SHT3X_NO_DEVICE)
    , _interval(SHT3X_SAMPLING_PERIOD)
    , _start(0)
    , _temperature(0)
    , _humidity(0)
    , _error(0)
    {
    }

    void begin(uint16_t interval = SHT3X_SAMPLING_PERIOD)
    {
      if (interval < SHT3X_MEASUREMENT_INTERVAL)
        interval = SHT3X_MEASUREMENT_INTERVAL;
      _start = (uint16_t)millis() - (_interval = interval) + SHT3X_RESET_TIME;
    }

    uint8_t error(void)
    {
      return _error;
    }

    int16_t temperatureF(void)
    {
      return _temperature * 9 / 5 + (32 * 16);
    }

    int16_t temperatureC(void)
    {
      return _temperature;
    }

    uint16_t humidity(void)
    {
      return _humidity;
    }

    bool conversion(void)
    {
      uint16_t t = 0;
      if (_status == SHT3X_BUSY)
        t = (uint16_t)millis() - _start;
      else if (measurement() == SHT3X_NO_DEVICE)
        return false;
      if (t < SHT3X_MEASUREMENT_TIME)
        delay(SHT3X_MEASUREMENT_TIME - t);
      return fetch() == SHT3X_READY;
    }

    uint8_t handle(void)
    {
      uint16_t now = (uint16_t)millis();
      switch (_status)
      {
        case SHT3X_NO_DEVICE:
        case SHT3X_IDLE:
          if ((uint16_t)(now - _start) >= _interval)
            measurement();
          break;
        case SHT3X_BUSY:
          if ((uint16_t)(now - _start) < SHT3X_MEASUREMENT_TIME)
            break;
          return fetch();
      }
      return _status;
    }
};

#endif // _SHT3X_H

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SHT3X.h - Temperatute and Humidity Library for Sensirion SHT3x(30/31/35)

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General

Public License along with this library; if not, write to the

Free Software Foundation, Inc., 59 Temple Place, Suite 330,

Boston, MA 02111-1307 USA

#ifndef _SHT3X_H

#define _SHT3X_H

#include <stdint.h>

#include <stdbool.h>

#define SHT3X_NO_DEVICE 0

#define SHT3X_IDLE 1

#define SHT3X_BUSY 2

#define SHT3X_READY 3

#define SHT3X_DEFAULT_ADDRESS 0x44

#define SHT3X_SINGLE_H_STRETCH 0x2C06

#define SHT3X_SINGLE_M_STRETCH 0x2C0D

#define SHT3X_SINGLE_L_STRETCH 0x2C10

#define SHT3X_SINGLE_H 0x2400

#define SHT3X_SINGLE_M 0x240B

#define SHT3X_SINGLE_L 0x2416

#define SHT3X_REPEAT_H_05MPS 0x2032

#define SHT3X_REPEAT_M_05MPS 0x2024

#define SHT3X_REPEAT_L_05MPS 0x202F

#define SHT3X_REPEAT_H_1MPS 0x2130

#define SHT3X_REPEAT_M_1MPS 0x2126

#define SHT3X_REPEAT_L_1MPS 0x212D

#define SHT3X_REPEAT_H_2MPS 0x2236

#define SHT3X_REPEAT_M_2MPS 0x2220

#define SHT3X_REPEAT_L_2MPS 0x222B

#define SHT3X_REPEAT_H_4MPS 0x2334

#define SHT3X_REPEAT_M_4MPS 0x2322

#define SHT3X_REPEAT_L_4MPS 0x2329

#define SHT3X_REPEAT_H_10MPS 0x2737

#define SHT3X_REPEAT_M_10MPS 0x2721

#define SHT3X_REPEAT_L_10MPS 0x272A

#define SHT3X_REPEAT_ART 0x2B32

#define SHT3X_REPEAT_STOP 0x3093

#define SHT3X_FETCH_DATA 0xE000

#define SHT3X_RESET 0x30A2

#define SHT3X_HEATER_ON 0x306D

#define SHT3X_HEATER_OFF 0x3066

#define SHT3X_STATUS_CLEAR 0x3041

#define SHT3X_STATUS_READ 0xF32D

#define SHT3X_RESET_TIME ( 1 + 1)

#define SHT3X_MEASUREMENT_TIME (15 + 1)

#define SHT3X_MEASUREMENT_INTERVAL 100

#define SHT3X_SAMPLING_PERIOD 1000

template<typename WIRE_T = TwoWire, WIRE_T& WIRE = Wire>

class SHT3X

{

private:

uint8_t _address;

uint8_t _status;

uint16_t _interval;

uint16_t _start;

int16_t _temperature;

uint16_t _humidity;

uint8_t _error;

bool command(uint16_t cmd)

{

WIRE.beginTransmission(_address);

WIRE.write(cmd >> 8);

WIRE.write(cmd & 0xFF);

return (_error = WIRE.endTransmission()) == 0;

}

uint8_t crc8(const uint8_t *data, int8_t len)

{

uint8_t crc = 0xFF;

while (--len >= 0)

{

crc ^= *data++;

for (int8_t i = 8; --i >= 0;)

crc = (crc & 0x80) ? (crc << 1) ^ 0x31 : (crc << 1);

}

return crc;

}

uint8_t fetch(void)

{

struct

{

struct

{

uint8_t high;

uint8_t low;

} temp;

uint8_t temp_crc;

struct

{

uint8_t high;

uint8_t low;

} humi;

uint8_t humi_crc;

} data;

uint16_t temp, humi;

_status = SHT3X_NO_DEVICE;

_start = (uint16_t)millis() - SHT3X_MEASUREMENT_TIME;

if (WIRE.requestFrom(_address, sizeof(data)) != sizeof(data))

return _status;

for (uint8_t i = 0; i < sizeof(data); i++)

((uint8_t *)&data)[i] = WIRE.read();

if (crc8((uint8_t *)&data.temp, sizeof(data.temp)) != data.temp_crc)

return _status;

if (crc8((uint8_t *)&data.humi, sizeof(data.humi)) != data.humi_crc)

return _status;

temp = ((uint16_t)data.temp.high << 8) | data.temp.low;

humi = ((uint16_t)data.humi.high << 8) | data.humi.low;

_temperature = ((uint32_t)temp * 175 * 16 / 65535) - (45 * 16);

_humidity = ((uint32_t)humi * 100 * 16 / 65535);

_status = SHT3X_IDLE;

return SHT3X_READY;

}

uint8_t measurement(void)

{

_status = command(SHT3X_SINGLE_H) ? SHT3X_BUSY : SHT3X_NO_DEVICE;

_start = (uint16_t)millis();

return _status;

}

uint8_t reset(void)

{

_status = SHT3X_NO_DEVICE;

if (command(SHT3X_RESET))

{

_status = SHT3X_IDLE;

delay(SHT3X_RESET_TIME);

}

_start = (uint16_t)millis();

return _status;

}

public:

SHT3X(uint8_t addr = SHT3X_DEFAULT_ADDRESS)

: _address(addr)

, _status(SHT3X_NO_DEVICE)

, _interval(SHT3X_SAMPLING_PERIOD)

, _start(0)

, _temperature(0)

, _humidity(0)

, _error(0)

{

}

void begin(uint16_t interval = SHT3X_SAMPLING_PERIOD)

{

if (interval < SHT3X_MEASUREMENT_INTERVAL)

interval = SHT3X_MEASUREMENT_INTERVAL;

_start = (uint16_t)millis() - (_interval = interval) + SHT3X_RESET_TIME;

}

uint8_t error(void)

{

return _error;

}

int16_t temperatureF(void)

{

return _temperature * 9 / 5 + (32 * 16);

}

int16_t temperatureC(void)

{

return _temperature;

}

uint16_t humidity(void)

{

return _humidity;

}

bool conversion(void)

{

uint16_t t = 0;

if (_status == SHT3X_BUSY)

t = (uint16_t)millis() - _start;

else if (measurement() == SHT3X_NO_DEVICE)

return false;

if (t < SHT3X_MEASUREMENT_TIME)

delay(SHT3X_MEASUREMENT_TIME - t);

return fetch() == SHT3X_READY;

}

uint8_t handle(void)

{

uint16_t now = (uint16_t)millis();

switch (_status)

{

case SHT3X_NO_DEVICE:

case SHT3X_IDLE:

if ((uint16_t)(now - _start) >= _interval)

measurement();

break;

case SHT3X_BUSY:

if ((uint16_t)(now - _start) < SHT3X_MEASUREMENT_TIME)

break;

return fetch();

}

return _status;

}

};

#endif // _SHT3X_H

カテゴリー: SHT3X

M5StickCでSHT31センサーを使う。