PyGameのコントローラーにM5stack via Bluetooth

#define M5STACK_MPU6886
#include "BluetoothSerial.h"
#include <M5Stack.h>

BluetoothSerial bts;
String btn;
float accX = 0.0F;  // Define variables for storing inertial sensor data
float accY = 0.0F;
float accZ = 0.0F;
float angle_th = 0.5F;  // r/l or u/l decision threashold

void read_imu() {
  M5.IMU.getAccelData(&accX,&accY,&accZ); //Stores the triaxial accelerometer. 
  M5.Lcd.setCursor(0, 90);
  M5.Lcd.printf(" accX");
  M5.Lcd.setCursor(0, 130);
  M5.Lcd.printf("%5.2f G", accX);
}

void setup() {
  M5.begin();
  M5.Power.begin(); //Init Power module.  
  M5.IMU.Init();    //Init IMU sensor.  
  M5.Lcd.setRotation(3);
  M5.Lcd.fillScreen(BLACK);
  M5.Lcd.setCursor(0, 0, 2);
  M5.Lcd.println("Maze game");
  bts.begin("ESP32test");
}

void loop() {
  btn = "";                           // button info. clear
  
  M5.update();
  if(M5.BtnA.wasPressed())
  {
    btn = "r";
  }
    if(M5.BtnB.wasPressed())
  {
    btn = "t";
  }
  if(M5.BtnC.wasPressed())
  {
    btn = "l";
  }

  read_imu();   // imu data read

  if(btn != "")
  {
    if (btn != "t")       // t(ButtonB) key terminate the Maze game
    {
      if (accX < -angle_th | accX > angle_th)       // if M5stack is tilted, r/l keys are changed to u/d
      {
        if (accX < -angle_th){ if (btn == "r") { btn = "u"; } else { btn = "d"; } } if (accX > angle_th)
        {
          if (btn == "r")
          {
            btn = "d";
          }
          else
          {
            btn = "u";
          }
        }
      }
    }

    bts.println(btn);      // send pressed key info.
    M5.Lcd.setCursor(0, 50, 2);
    M5.Lcd.println(btn);
  }

  delay(100);

}