M5Stack 買った

第二の産業革命を起こすとも言われているM5 Stack を購入しました。

#M5Stack 買っちった pic.twitter.com/Hbx6r3RtM1
— しんじ (@shinjimp3) March 16, 2019

www.m5stack.com

購入のきっかけになったツイートです。

職場の最寄駅の電車が本数少ないので，次の電車があと何分で来るか分かるガジェットをM5stackで作りました．#M5Stack https://t.co/o7w7MOcRWE pic.twitter.com/c9ICmC6J73
— Keisuke KAWAHARA (@ktansai) February 27, 2019

M5Stackがどんなものかというと，ESP32というArduino IDEでコード書けるマイコンに，電子工作で使いそうな基本的なものだいたい全部乗せみたいなやつです。液晶と3つのボタンと5×5のガワが印象的で見た目もスマート。

Stackって名前だけにモジュール(Arduino シールド基板みたいなやつ？)を重ねて積めるらしいです。

細かい解説は上のリンクに譲って，個人的に魅力的だと思ったのは，

LCD(320×240の液晶)ついてて描画も簡単
ESP32がWiFiモジュール積んでる
SDカードのスロットついててmp3の音声流せる
Bluetoothも行けそう
磁石ついててホワイトボードとか玄関のドアに貼り付けられる
バッテリーも標準装備でケーブル切り離してもしばらくOK

です。

特にちょっとした解像度の液晶と無線通信と音声再生は今までのArduino工作の経験からちょっとハードルが高かったので，その辺が簡単にできそうなのはうれしい。（まだやってないけど）

M5Stack GRAY でIMUを使う

M5Stackにもバリエーションがあって，今回はBASICとGRAYを買いました。 BASICに9軸IMU(加速度，ジャイロ，磁気センサ)と温度センサ積んだのがGRAYです。

サンプルスケッチを見る

ひとまず重力加速度からボールコロコロでもしたいなと思って，加速度センサ使ってそうなサンプルスケッチを見ました。

/* MPU9250 Basic Example Code
 by: Kris Winer
 date: April 1, 2014
 license: Beerware - Use this code however you'd like. If you
 find it useful you can buy me a beer some time.
 Modified by Brent Wilkins July 19, 2016

 Demonstrate basic MPU-9250 functionality including parameterizing the register
 addresses, initializing the sensor, getting properly scaled accelerometer,
 gyroscope, and magnetometer data out. Added display functions to allow display
 to on breadboard monitor. Addition of 9 DoF sensor fusion using open source
 Madgwick and Mahony filter algorithms. Sketch runs on the 3.3 V 8 MHz Pro Mini
 and the Teensy 3.1.
 */

#include <M5Stack.h>
#include "utility/MPU9250.h"
#include "utility/quaternionFilters.h"

#define processing_out false
#define AHRS true         // Set to false for basic data read
#define SerialDebug true  // Set to true to get Serial output for debugging
#define LCD

MPU9250 IMU;
// Kalman kalmanX, kalmanY, kalmanZ; // Create the Kalman instances

void setup()
{
  M5.begin();
  Wire.begin();

#ifdef LCD
  // Start device display with ID of sensor
  M5.Lcd.fillScreen(BLACK);
  M5.Lcd.setTextColor(WHITE ,BLACK); // Set pixel color; 1 on the monochrome screen
  M5.Lcd.setTextSize(2);
  M5.Lcd.setCursor(0,0); M5.Lcd.print("MPU9250");
  M5.Lcd.setTextSize(1);
  M5.Lcd.setCursor(0, 20); M5.Lcd.print("9-DOF 16-bit");
  M5.Lcd.setCursor(0, 30); M5.Lcd.print("motion sensor");
  M5.Lcd.setCursor(20,40); M5.Lcd.print("60 ug LSB");
  delay(1000);

  // Set up for data display
  M5.Lcd.setTextSize(1); // Set text size to normal, 2 is twice normal etc.
  M5.Lcd.fillScreen(BLACK);   // clears the screen and buffer
#endif // LCD

  // Read the WHO_AM_I register, this is a good test of communication
  byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);
  Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);
  Serial.print(" I should be "); Serial.println(0x71, HEX);

#ifdef LCD
  M5.Lcd.setCursor(20,0); M5.Lcd.print("MPU9250");
  M5.Lcd.setCursor(0,10); M5.Lcd.print("I AM");
  M5.Lcd.setCursor(0,20); M5.Lcd.print(c, HEX);
  M5.Lcd.setCursor(0,30); M5.Lcd.print("I Should Be");
  M5.Lcd.setCursor(0,40); M5.Lcd.print(0x71, HEX);
  delay(1000);
#endif // LCD

  // if (c == 0x71) // WHO_AM_I should always be 0x68
  {
    Serial.println("MPU9250 is online...");

    // Start by performing self test and reporting values
    IMU.MPU9250SelfTest(IMU.SelfTest);
    Serial.print("x-axis self test: acceleration trim within : ");
    Serial.print(IMU.SelfTest[0],1); Serial.println("% of factory value");
    Serial.print("y-axis self test: acceleration trim within : ");
    Serial.print(IMU.SelfTest[1],1); Serial.println("% of factory value");
    Serial.print("z-axis self test: acceleration trim within : ");
    Serial.print(IMU.SelfTest[2],1); Serial.println("% of factory value");
    Serial.print("x-axis self test: gyration trim within : ");
    Serial.print(IMU.SelfTest[3],1); Serial.println("% of factory value");
    Serial.print("y-axis self test: gyration trim within : ");
    Serial.print(IMU.SelfTest[4],1); Serial.println("% of factory value");
    Serial.print("z-axis self test: gyration trim within : ");
    Serial.print(IMU.SelfTest[5],1); Serial.println("% of factory value");

    // Calibrate gyro and accelerometers, load biases in bias registers
    IMU.calibrateMPU9250(IMU.gyroBias, IMU.accelBias);

#ifdef LCD
    M5.Lcd.fillScreen(BLACK);
    M5.Lcd.setTextSize(1);
    M5.Lcd.setCursor(0, 0); M5.Lcd.print("MPU9250 bias");
    M5.Lcd.setCursor(0, 16); M5.Lcd.print(" x   y   z  ");

    M5.Lcd.setCursor(0,  32); M5.Lcd.print((int)(1000*IMU.accelBias[0]));
    M5.Lcd.setCursor(32, 32); M5.Lcd.print((int)(1000*IMU.accelBias[1]));
    M5.Lcd.setCursor(64, 32); M5.Lcd.print((int)(1000*IMU.accelBias[2]));
    M5.Lcd.setCursor(96, 32); M5.Lcd.print("mg");

    M5.Lcd.setCursor(0,  48); M5.Lcd.print(IMU.gyroBias[0], 1);
    M5.Lcd.setCursor(32, 48); M5.Lcd.print(IMU.gyroBias[1], 1);
    M5.Lcd.setCursor(64, 48); M5.Lcd.print(IMU.gyroBias[2], 1);
    M5.Lcd.setCursor(96, 48); M5.Lcd.print("o/s");
    delay(1000);
#endif // LCD

    IMU.initMPU9250();
    // Initialize device for active mode read of acclerometer, gyroscope, and
    // temperature
    Serial.println("MPU9250 initialized for active data mode....");

    // Read the WHO_AM_I register of the magnetometer, this is a good test of
    // communication
    byte d = IMU.readByte(AK8963_ADDRESS, WHO_AM_I_AK8963);
    Serial.print("AK8963 "); Serial.print("I AM "); Serial.print(d, HEX);
    Serial.print(" I should be "); Serial.println(0x48, HEX);

#ifdef LCD
    M5.Lcd.fillScreen(BLACK);
    M5.Lcd.setCursor(20,0); M5.Lcd.print("AK8963");
    M5.Lcd.setCursor(0,10); M5.Lcd.print("I AM");
    M5.Lcd.setCursor(0,20); M5.Lcd.print(d, HEX);
    M5.Lcd.setCursor(0,30); M5.Lcd.print("I Should Be");
    M5.Lcd.setCursor(0,40); M5.Lcd.print(0x48, HEX);
    delay(1000);
#endif // LCD

    // Get magnetometer calibration from AK8963 ROM
    IMU.initAK8963(IMU.magCalibration);
    // Initialize device for active mode read of magnetometer
    Serial.println("AK8963 initialized for active data mode....");
    if (Serial)
    {
      //  Serial.println("Calibration values: ");
      Serial.print("X-Axis sensitivity adjustment value ");
      Serial.println(IMU.magCalibration[0], 2);
      Serial.print("Y-Axis sensitivity adjustment value ");
      Serial.println(IMU.magCalibration[1], 2);
      Serial.print("Z-Axis sensitivity adjustment value ");
      Serial.println(IMU.magCalibration[2], 2);
    }

#ifdef LCD
    M5.Lcd.fillScreen(BLACK);
    M5.Lcd.setCursor(20,0); M5.Lcd.print("AK8963");
    M5.Lcd.setCursor(0,10); M5.Lcd.print("ASAX "); M5.Lcd.setCursor(50,10);
    M5.Lcd.print(IMU.magCalibration[0], 2);
    M5.Lcd.setCursor(0,20); M5.Lcd.print("ASAY "); M5.Lcd.setCursor(50,20);
    M5.Lcd.print(IMU.magCalibration[1], 2);
    M5.Lcd.setCursor(0,30); M5.Lcd.print("ASAZ "); M5.Lcd.setCursor(50,30);
    M5.Lcd.print(IMU.magCalibration[2], 2);
    delay(1000);
    #endif // LCD
  } // if (c == 0x71)
  // else
  // {
  //   Serial.print("Could not connect to MPU9250: 0x");
  //   Serial.println(c, HEX);
  //   while(1) ; // Loop forever if communication doesn't happen
  // }

  M5.Lcd.setTextSize(1);
  M5.Lcd.setTextColor(GREEN ,BLACK);
  M5.Lcd.fillScreen(BLACK);
}

void loop()
{
  // If intPin goes high, all data registers have new data
  // On interrupt, check if data ready interrupt
  if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
  {  
    IMU.readAccelData(IMU.accelCount);  // Read the x/y/z adc values
    IMU.getAres();

    // Now we'll calculate the accleration value into actual g's
    // This depends on scale being set
    IMU.ax = (float)IMU.accelCount[0]*IMU.aRes; // - accelBias[0];
    IMU.ay = (float)IMU.accelCount[1]*IMU.aRes; // - accelBias[1];
    IMU.az = (float)IMU.accelCount[2]*IMU.aRes; // - accelBias[2];

    IMU.readGyroData(IMU.gyroCount);  // Read the x/y/z adc values
    IMU.getGres();

    // Calculate the gyro value into actual degrees per second
    // This depends on scale being set
    IMU.gx = (float)IMU.gyroCount[0]*IMU.gRes;
    IMU.gy = (float)IMU.gyroCount[1]*IMU.gRes;
    IMU.gz = (float)IMU.gyroCount[2]*IMU.gRes;

    IMU.readMagData(IMU.magCount);  // Read the x/y/z adc values
    IMU.getMres();
    // User environmental x-axis correction in milliGauss, should be
    // automatically calculated
    IMU.magbias[0] = +470.;
    // User environmental x-axis correction in milliGauss TODO axis??
    IMU.magbias[1] = +120.;
    // User environmental x-axis correction in milliGauss
    IMU.magbias[2] = +125.;

    // Calculate the magnetometer values in milliGauss
    // Include factory calibration per data sheet and user environmental
    // corrections
    // Get actual magnetometer value, this depends on scale being set
    IMU.mx = (float)IMU.magCount[0]*IMU.mRes*IMU.magCalibration[0] -
               IMU.magbias[0];
    IMU.my = (float)IMU.magCount[1]*IMU.mRes*IMU.magCalibration[1] -
               IMU.magbias[1];
    IMU.mz = (float)IMU.magCount[2]*IMU.mRes*IMU.magCalibration[2] -
               IMU.magbias[2];
  } // if (readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)

  // Must be called before updating quaternions!
  IMU.updateTime();

  // Sensors x (y)-axis of the accelerometer is aligned with the y (x)-axis of
  // the magnetometer; the magnetometer z-axis (+ down) is opposite to z-axis
  // (+ up) of accelerometer and gyro! We have to make some allowance for this
  // orientationmismatch in feeding the output to the quaternion filter. For the
  // MPU-9250, we have chosen a magnetic rotation that keeps the sensor forward
  // along the x-axis just like in the LSM9DS0 sensor. This rotation can be
  // modified to allow any convenient orientation convention. This is ok by
  // aircraft orientation standards! Pass gyro rate as rad/s
//  MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f,  my,  mx, mz);
  MahonyQuaternionUpdate(IMU.ax, IMU.ay, IMU.az, IMU.gx*DEG_TO_RAD,
                         IMU.gy*DEG_TO_RAD, IMU.gz*DEG_TO_RAD, IMU.my,
                         IMU.mx, IMU.mz, IMU.deltat);

  if (!AHRS)
  {
    IMU.delt_t = millis() - IMU.count;
    if (IMU.delt_t > 500)
    {
      if(SerialDebug)
      {
        // Print acceleration values in milligs!
        Serial.print("X-acceleration: "); Serial.print(1000*IMU.ax);
        Serial.print(" mg ");
        Serial.print("Y-acceleration: "); Serial.print(1000*IMU.ay);
        Serial.print(" mg ");
        Serial.print("Z-acceleration: "); Serial.print(1000*IMU.az);
        Serial.println(" mg ");

        // Print gyro values in degree/sec
        Serial.print("X-gyro rate: "); Serial.print(IMU.gx, 3);
        Serial.print(" degrees/sec ");
        Serial.print("Y-gyro rate: "); Serial.print(IMU.gy, 3);
        Serial.print(" degrees/sec ");
        Serial.print("Z-gyro rate: "); Serial.print(IMU.gz, 3);
        Serial.println(" degrees/sec");

        // Print mag values in degree/sec
        Serial.print("X-mag field: "); Serial.print(IMU.mx);
        Serial.print(" mG ");
        Serial.print("Y-mag field: "); Serial.print(IMU.my);
        Serial.print(" mG ");
        Serial.print("Z-mag field: "); Serial.print(IMU.mz);
        Serial.println(" mG");

        IMU.tempCount = IMU.readTempData();  // Read the adc values
        // Temperature in degrees Centigrade
        IMU.temperature = ((float) IMU.tempCount) / 333.87 + 21.0;
        // Print temperature in degrees Centigrade
        Serial.print("Temperature is ");  Serial.print(IMU.temperature, 1);
        Serial.println(" degrees C");
        Serial.println("");
      }

#ifdef LCD
      M5.Lcd.fillScreen(BLACK);
      M5.Lcd.setTextColor(GREEN ,BLACK);
      M5.Lcd.setCursor(0, 0); M5.Lcd.print("MPU9250/AK8963");
      M5.Lcd.setCursor(0, 32); M5.Lcd.print(" x   y   z  ");

      M5.Lcd.setCursor(0,  48); M5.Lcd.print((int)(1000*IMU.ax));
      M5.Lcd.setCursor(32, 48); M5.Lcd.print((int)(1000*IMU.ay));
      M5.Lcd.setCursor(64, 48); M5.Lcd.print((int)(1000*IMU.az));
      M5.Lcd.setCursor(96, 48); M5.Lcd.print("mg");

      M5.Lcd.setCursor(0,  64); M5.Lcd.print((int)(IMU.gx));
      M5.Lcd.setCursor(32, 64); M5.Lcd.print((int)(IMU.gy));
      M5.Lcd.setCursor(64, 64); M5.Lcd.print((int)(IMU.gz));
      M5.Lcd.setCursor(96, 64); M5.Lcd.print("o/s");

      M5.Lcd.setCursor(0,  96); M5.Lcd.print((int)(IMU.mx));
      M5.Lcd.setCursor(32, 96); M5.Lcd.print((int)(IMU.my));
      M5.Lcd.setCursor(64, 96); M5.Lcd.print((int)(IMU.mz));
      M5.Lcd.setCursor(96, 96); M5.Lcd.print("mG");

      M5.Lcd.setCursor(0,  128); M5.Lcd.print("Gyro T ");
      M5.Lcd.setCursor(50,  128); M5.Lcd.print(IMU.temperature, 1);
      M5.Lcd.print(" C");
#endif // LCD

      IMU.count = millis();
      // digitalWrite(myLed, !digitalRead(myLed));  // toggle led
    } // if (IMU.delt_t > 500)
  } // if (!AHRS)
  else
  {
    // Serial print and/or display at 0.5 s rate independent of data rates
    IMU.delt_t = millis() - IMU.count;

    // update LCD once per half-second independent of read rate
    // if (IMU.delt_t > 500)
    if (IMU.delt_t > 100)
    {
      if(SerialDebug)
      {
        Serial.print("ax = "); Serial.print((int)1000*IMU.ax);
        Serial.print(" ay = "); Serial.print((int)1000*IMU.ay);
        Serial.print(" az = "); Serial.print((int)1000*IMU.az);
        Serial.println(" mg");

        Serial.print("gx = "); Serial.print( IMU.gx, 2);
        Serial.print(" gy = "); Serial.print( IMU.gy, 2);
        Serial.print(" gz = "); Serial.print( IMU.gz, 2);
        Serial.println(" deg/s");

        Serial.print("mx = "); Serial.print( (int)IMU.mx );
        Serial.print(" my = "); Serial.print( (int)IMU.my );
        Serial.print(" mz = "); Serial.print( (int)IMU.mz );
        Serial.println(" mG");

        Serial.print("q0 = "); Serial.print(*getQ());
        Serial.print(" qx = "); Serial.print(*(getQ() + 1));
        Serial.print(" qy = "); Serial.print(*(getQ() + 2));
        Serial.print(" qz = "); Serial.println(*(getQ() + 3));
      }

// Define output variables from updated quaternion---these are Tait-Bryan
// angles, commonly used in aircraft orientation. In this coordinate system,
// the positive z-axis is down toward Earth. Yaw is the angle between Sensor
// x-axis and Earth magnetic North (or true North if corrected for local
// declination, looking down on the sensor positive yaw is counterclockwise.
// Pitch is angle between sensor x-axis and Earth ground plane, toward the
// Earth is positive, up toward the sky is negative. Roll is angle between
// sensor y-axis and Earth ground plane, y-axis up is positive roll. These
// arise from the definition of the homogeneous rotation matrix constructed
// from quaternions. Tait-Bryan angles as well as Euler angles are
// non-commutative; that is, the get the correct orientation the rotations
// must be applied in the correct order which for this configuration is yaw,
// pitch, and then roll.
// For more see
// http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
// which has additional links.
      IMU.yaw   = atan2(2.0f * (*(getQ()+1) * *(getQ()+2) + *getQ() *
                    *(getQ()+3)), *getQ() * *getQ() + *(getQ()+1) * *(getQ()+1)
                    - *(getQ()+2) * *(getQ()+2) - *(getQ()+3) * *(getQ()+3));
      IMU.pitch = -asin(2.0f * (*(getQ()+1) * *(getQ()+3) - *getQ() *
                    *(getQ()+2)));
      IMU.roll  = atan2(2.0f * (*getQ() * *(getQ()+1) + *(getQ()+2) *
                    *(getQ()+3)), *getQ() * *getQ() - *(getQ()+1) * *(getQ()+1)
                    - *(getQ()+2) * *(getQ()+2) + *(getQ()+3) * *(getQ()+3));
      IMU.pitch *= RAD_TO_DEG;
      IMU.yaw   *= RAD_TO_DEG;
      // Declination of SparkFun Electronics (40°05'26.6"N 105°11'05.9"W) is
      //   8° 30' E  ± 0° 21' (or 8.5°) on 2016-07-19
      // - http://www.ngdc.noaa.gov/geomag-web/#declination
      IMU.yaw   -= 8.5;
      IMU.roll  *= RAD_TO_DEG;

      if(SerialDebug)
      {
        Serial.print("Yaw, Pitch, Roll: ");
        Serial.print(IMU.yaw, 2);
        Serial.print(", ");
        Serial.print(IMU.pitch, 2);
        Serial.print(", ");
        Serial.println(IMU.roll, 2);

        Serial.print("rate = ");
        Serial.print((float)IMU.sumCount/IMU.sum, 2);
        Serial.println(" Hz");
        Serial.println("");
      }

#ifdef LCD
      // M5.Lcd.fillScreen(BLACK);
      M5.Lcd.setTextFont(2);

      M5.Lcd.setCursor(0, 0); M5.Lcd.print("     x       y       z ");
      M5.Lcd.setCursor(0,  24);
      M5.Lcd.printf("% 6d  % 6d  % 6d     mg   \r\n",  (int)(1000*IMU.ax), (int)(1000*IMU.ay), (int)(1000*IMU.az));
      M5.Lcd.setCursor(0,  44);
      M5.Lcd.printf("% 6d  % 6d  % 6d      o/s  \r\n", (int)(IMU.gx), (int)(IMU.gy), (int)(IMU.gz));
      M5.Lcd.setCursor(0,  64);
      M5.Lcd.printf("% 6d  % 6d  % 6d     mG    \r\n",  (int)(IMU.mx), (int)(IMU.my), (int)(IMU.mz));
  
      M5.Lcd.setCursor(0,  100);
      M5.Lcd.printf("  yaw: % 5.2f    pitch: % 5.2f    roll: % 5.2f   \r\n",(IMU.yaw), (IMU.pitch), (IMU.roll));

    // With these settings the filter is updating at a ~145 Hz rate using the
    // Madgwick scheme and >200 Hz using the Mahony scheme even though the
    // display refreshes at only 2 Hz. The filter update rate is determined
    // mostly by the mathematical steps in the respective algorithms, the
    // processor speed (8 MHz for the 3.3V Pro Mini), and the magnetometer ODR:
    // an ODR of 10 Hz for the magnetometer produce the above rates, maximum
    // magnetometer ODR of 100 Hz produces filter update rates of 36 - 145 and
    // ~38 Hz for the Madgwick and Mahony schemes, respectively. This is
    // presumably because the magnetometer read takes longer than the gyro or
    // accelerometer reads. This filter update rate should be fast enough to
    // maintain accurate platform orientation for stabilization control of a
    // fast-moving robot or quadcopter. Compare to the update rate of 200 Hz
    // produced by the on-board Digital Motion Processor of Invensense's MPU6050
    // 6 DoF and MPU9150 9DoF sensors. The 3.3 V 8 MHz Pro Mini is doing pretty
    // well!

      // M5.Lcd.setCursor(0, 60);
      // M5.Lcd.printf("yaw:%6.2f   pitch:%6.2f   roll:%6.2f  ypr \r\n",(IMU.yaw), (IMU.pitch), (IMU.roll));
      M5.Lcd.setCursor(12, 144); 
      M5.Lcd.print("rt: ");
      M5.Lcd.print((float) IMU.sumCount / IMU.sum, 2);
      M5.Lcd.print(" Hz");
#endif // LCD

      IMU.count = millis();
      IMU.sumCount = 0;
      IMU.sum = 0;

#if(processing_out)

      Serial.print(((IMU.yaw)));    Serial.print(";");
      Serial.print(((IMU.pitch))); Serial.print(";");
      Serial.print(((IMU.roll)));   Serial.print(";");
      Serial.print(26.5);    Serial.print(";");
      Serial.print(0.01);    Serial.print(";");
      Serial.print(0.02);    Serial.println();
#endif
    } // if (IMU.delt_t > 500)
  } // if (AHRS)
}

長い！！！！

挫折しかけたわ！！！！危ねぇ！！！！

サンプルで一通り機能見せたり，表示したいものも多いので，色々盛り盛りになっているのだと思います。

必要なとこだけ抜き取る

とりあえず，加速度三軸の値だけ取ってこれればいいやという気持ちなので，必要そうなところだけ抜き出してみました。通信相手のアドレスの確認，他のセンサ(ジャイロと磁気)の計測，printの部分を無視して取り出すと。

#include <M5Stack.h>
#include "utility/MPU9250.h"

MPU9250 IMU;

void setup() {
  M5.begin();
  //  serial for debugging
  Serial.begin(115200);
  //  i2c as a master
  Wire.begin();
  IMU.initMPU9250(); 

}

void loop() {

  if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
  {  
    IMU.readAccelData(IMU.accelCount);  // Read the x/y/z adc values
    IMU.getAres();

    // Now we'll calculate the accleration value into actual g's
    // This depends on scale being set
    IMU.ax = (float)IMU.accelCount[0]*IMU.aRes; // - accelBias[0];
    IMU.ay = (float)IMU.accelCount[1]*IMU.aRes; // - accelBias[1];
    IMU.az = (float)IMU.accelCount[2]*IMU.aRes; // - accelBias[2];
    //あとは 加速度3軸分のfloatデータ IMU.ax, IMU.ay, IMU.az でお好きに…
}

だいぶすっきりした。

やっているのは，

ライブラリを用意。

#include "utility/MPU9250.h"

IMUのインスタンスを作る。

MPU9250 IMU;

通信を始める。

  Wire.begin();

IMUを初期化する。

  IMU.initMPU9250();

データを読む。

  if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
  {  
    IMU.readAccelData(IMU.accelCount);  // Read the x/y/z adc values
    IMU.getAres();

    // Now we'll calculate the accleration value into actual g's
    // This depends on scale being set
    IMU.ax = (float)IMU.accelCount[0]*IMU.aRes; // - accelBias[0];
    IMU.ay = (float)IMU.accelCount[1]*IMU.aRes; // - accelBias[1];
    IMU.az = (float)IMU.accelCount[2]*IMU.aRes; // - accelBias[2];
    //あとは 加速度3軸分のfloatデータ IMU.ax, IMU.ay, IMU.az でお好きに…
}

…です。

ボールコロコロさせた

加速度取る最小限のコードが分かったので，ボールコロコロさせました。

加速度センサ大好きおじさんなのですーぐこういうのやっちゃう。 pic.twitter.com/QuT694XHVe
— しんじ (@shinjimp3) March 16, 2019

楽しい！

以下，スケッチです。

#include <M5Stack.h>
#include "utility/MPU9250.h"

MPU9250 IMU;

//ボールの初期位置，初速度
float posx = 160;
float posy = 120;
float velx = 0;
float vely = 0;
int radius = 5; //描画するボールの半径

//ループ一回分の時間とそれを計算するためのタイマーです。
unsigned int dt = 0;
unsigned int timer = millis();


void setup() {
  M5.begin();
  //  serial for debugging
  Serial.begin(115200);
  //  i2c as a master
  Wire.begin();
  IMU.initMPU9250();
  

}

void loop() {

  if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
  {  
    IMU.readAccelData(IMU.accelCount);  // Read the x/y/z adc values
    IMU.getAres();

    // Now we'll calculate the accleration value into actual g's
    // This depends on scale being set
    IMU.ax = (float)IMU.accelCount[0]*IMU.aRes; // - accelBias[0];
    IMU.ay = (float)IMU.accelCount[1]*IMU.aRes; // - accelBias[1];
    IMU.az = (float)IMU.accelCount[2]*IMU.aRes; // - accelBias[2];

    //これはPC側のシリアルモニタで見ます。デバッグ用です。
    Serial.print(timer);
    Serial.print(' ');
    Serial.print(dt);
    Serial.print(' ');
    Serial.print(IMU.ax);
    Serial.print(' ');
    Serial.println(IMU.ay);

    M5.Lcd.fillScreen(BLACK);
  
    dt = millis() - timer;
    float dtf = (float)dt/1000; //運動の計算用に使うものは単位[s]にしときます。
    //速度更新
    velx = velx + -500 * IMU.ax * dtf; //500は適当に調整しました。慣性を決めます。
    vely = vely + 500 * IMU.ay * dtf;

    //位置更新
    posx = posx + velx * dtf;
    posy = posy + vely * dtf;
    timer = millis();

    //はみ出さない，速くしすぎない
    posx = constrain(posx, 0, 319);
    posy = constrain(posy, 0, 239);
    velx = constrain(velx, -319, 319);
    vely = constrain(vely, -239, 239);
    
    //端っこ来たら跳ね返る
    if(posx == 0 && velx < 0)
      velx = velx * -0.8;
    if(posx == 319 && velx > 0)
      velx = velx * -0.8;
    if(posy == 0 && vely < 0)
      vely = vely * -0.8;
    if(posy == 239 && vely > 0)
      vely = vely * -0.8;
    
    //ボールの描画
    M5.Lcd.fillCircle((int)posx, (int)posy, radius, RED);
    
  }
  delay(50);
}

今回はひとまず加速度の取得だけ簡単に試してみました。

せっかくなので今まであまり踏み込んでこなかった無線通信で連携させてやって遊んでみたいですね。 2つ買ったので。

ちなみにmicro:bit君ですが諸事情あって積み基板になりました。

それではまた。

shinji00のブログ

M5Stack GRAY 買って最小限のコードで加速度センサを試した

M5Stack 買った

M5Stack GRAY でIMUを使う

サンプルスケッチを見る

必要なとこだけ抜き取る

ボールコロコロさせた