STM32G031のI2CスレーブモードでGP2Y0A21YK(赤外線距離センサー)の値をマスターで受信する。



目的
I2Cのテスト
距離センサーのI2C化
I2C間通信の応用
赤外線距離センターを使い距離を測る。

![o_con324.jpg](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/840352/99d50386-3cef-8af7-1db0-5075c5bd6904.jpeg)




忙しい人よう

i2c_slave_ir_length_031_1のバイナリー


https://os.mbed.com/users/caa45040/code/f303_h_p1//file/812ae9369028/i2c_slave_ir_length_031_BIN/



スレーブのプログラム



```c++


//i2c_slave_ir_length_031_1


#include <Arduino.h>
#include <Wire.h>


//10の割り算 0から1028までは、正しい。主に0から999
#define DIV10(n) ((n*205)>>11)

byte b=200; // ((s-140)*10)+200 -> 800


//80-20
unsigned char qq[] = {
  80, 78, 77, 76, 75, 75, 74, 73, 72, 71,
  70, 69, 68, 68, 67, 66, 65, 65, 64, 63,
  63, 62, 61, 61, 60, 60, 59, 58, 58, 57,
  57, 56, 56, 55, 55, 54, 54, 53, 53, 52,
  52, 51, 51, 50, 50, 50, 49, 49, 48, 48,
  47, 47, 47, 46, 46, 46, 45, 45, 45, 44,
  44, 44, 43, 43, 43, 42, 42, 42, 41, 41,
  41, 41, 40, 40, 40, 40, 39, 39, 39, 38,
  38, 38, 38, 37, 37, 37, 37, 37, 36, 36,
  36, 36, 35, 35, 35, 35, 35, 34, 34, 34,
  34, 34, 33, 33, 33, 33, 33, 32, 32, 32,
  32, 32, 32, 31, 31, 31, 31, 31, 31, 30,
  30, 30, 30, 30, 30, 30, 29, 29, 29, 29,
  29, 29, 28, 28, 28, 28, 28, 28, 28, 28,
  27, 27, 27, 27, 27, 27, 27, 27, 26, 26,
  26, 26, 26, 26, 26, 26, 25, 25, 25, 25,
  25, 25, 25, 25, 25, 25, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 23, 22, 22, 22, 22,
  22, 22, 22, 22, 22, 22, 22, 22, 21, 21,
  21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
  21, 20, 20, 20, 20, 20, 20, 20, 20, 20,
  20, 20, 20, 20, 20, 20
};

//20-10
unsigned char pp[] = {
  200, 199, 198, 197, 196, 196, 195, 194, 193, 193,
  192, 191, 190, 190, 189, 188, 187, 187, 186, 185,
  185, 184, 183, 183, 182, 181, 181, 180, 179, 179,
  178, 177, 177, 176, 176, 175, 174, 174, 173, 173,
  172, 171, 171, 170, 170, 169, 168, 168, 167, 167,
  166, 166, 165, 165, 164, 163, 163, 162, 162, 161,
  161, 160, 160, 159, 159, 158, 158, 157, 157, 156,
  156, 155, 155, 154, 154, 153, 153, 152, 152, 151,
  151, 151, 150, 150, 149, 149, 148, 148, 147, 147,
  147, 146, 146, 145, 145, 144, 144, 144, 143, 143,
  142, 142, 142, 141, 141, 140, 140, 140, 139, 139,
  138, 138, 138, 137, 137, 136, 136, 136, 135, 135,
  135, 134, 134, 134, 133, 133, 132, 132, 132, 131,
  131, 131, 130, 130, 130, 129, 129, 129, 128, 128,
  128, 127, 127, 127, 126, 126, 126, 125, 125, 125,
  125, 124, 124, 124, 123, 123, 123, 122, 122, 122,
  121, 121, 121, 121, 120, 120, 120, 119, 119, 119,
  119, 118, 118, 118, 117, 117, 117, 117, 116, 116,
  116, 116, 115, 115, 115, 114, 114, 114, 114, 113,
  113, 113, 113, 112, 112, 112, 112, 111, 111, 111,
  111, 110, 110, 110, 110, 109, 109, 109, 109, 108,
  108, 108, 108, 107, 107, 107, 107, 107, 106, 106,
  106, 106, 105, 105, 105, 105, 105, 104, 104, 104,
  104, 103, 103, 103, 103, 103, 102, 102, 102, 102,
  102, 101, 101, 101, 101, 101, 100, 100, 100, 100,
  100
};

//10-6
unsigned char oo[] = {
  100, 99, 98, 98, 97, 97, 96, 96, 95, 95,
  94, 94, 93, 93, 92, 92, 91, 91, 90, 90,
  90, 89, 89, 88, 88, 87, 87, 86, 86, 86,
  85, 85, 84, 84, 84, 83, 83, 82, 82, 82,
  81, 81, 81, 80, 80, 80, 79, 79, 78, 78,
  77, 77, 76, 76, 75, 75, 74, 74, 74, 73,
  73, 72, 72, 71, 71, 71, 70, 70, 69, 69,
  68, 67, 66, 66, 65, 64, 63, 63, 62, 61,
  61, 60, 60
};

//赤外線距離センサー(GP2Y0A21YK)の電圧から距離を求める。
//Voltage //電圧
int ir_len_i(int Voltage)
{

  int ir_length;   //長さ

  if (Voltage >= 0    && Voltage <= 400 ) {
    return (800);
  }
  if (Voltage >= 3120 && Voltage <= 5000) {
    return (60);
  }

  if        (Voltage >= 400 && Voltage <= 1300 ) { //80-20

    ir_length = (int)qq[(Voltage - 400) >> 2];
    ir_length = ir_length * 10;

  } else if (Voltage >= 1300 && Voltage <= 2300 ) { //20-10

    ir_length = (int)pp[(Voltage - 1300) >> 2];

  } else if (Voltage >= 2300 && Voltage <= 3120  ) { //10-6

    //ir_length = (int)oo[(Voltage - 2300) / 10];
    ir_length = (int)oo[  ((Voltage - 2300)*205)>>11 ]; //10の割り算

  }//end if

  //戻り値
  return (ir_length);

} //ir_le_i


void setup() {

  //I2Cの初期化
  Wire.begin(PA12, PA11); //stm32g031
  
  Wire.begin(8);// Slave ID #8
  Wire.onRequest(requestEvent);

}//setup


void loop() {
}//loop


void requestEvent() {

  Wire.write(b);

  
  int sensorValue; //センサーの読み取り値
  int Voltage;     //電圧
  int ir_length;   //長さ

  //アナログ値の読み込み
  analogReadResolution(12); //adc 12bit mode
  sensorValue = analogRead(A9); // PB7  PIN1 031

  //アナログ値を電圧に変換
  Voltage = (sensorValue * 3300) >> 12; //stm32　(s*3300)/4096
  if (Voltage > 5000) {Voltage = 5000;} //アナログ変換エラー対策
  if (Voltage < 0   ) {Voltage = 0;   }

  //赤外線距離センサー(GP2Y0A21YK)の電圧から距離を求める。
  ir_length = ir_len_i(Voltage);

  if ( ir_length <= 199 ) {

  b = ir_length - 60;

  } else {

  b = (byte)(   DIV10(ir_length)-20+140 );
  
  }

  //b = 200;//debug
  
}//requestEvent



```


マスターのプログラム


```c++



//i2c_master_ir_length_031_1


#include <Arduino.h>
#include <Wire.h>

//10の割り算 0から1028までは、正しい。主に0から999
#define DIV10(n) ((n*205)>>11)

#define in7      PA0  // 4pin

#define DW   digitalWrite

#define UART_DELAY 102   //  9600bps ok 031


//仮想シリアルへの一文字出力 9600bps
int pc_putc(char ch) {

  DW(in7, HIGH);

  DW(in7, LOW);//START
  delayMicroseconds(UART_DELAY);

  for (int ii = 0; ii < 8; ii++) {
    DW(in7, (ch >> ii) & 1  );
    delayMicroseconds(UART_DELAY);
  }//for

  DW(in7, HIGH);//Stop
  delayMicroseconds(UART_DELAY);

  return (0);

}//pc_putc


//文字列の表示
int pc_printf(char *str1) {

  //文字の中身がゼロか
  while (*str1) {

    //一文字出力
    pc_putc(*str1 ++);

  } //while

  //戻り値
  return (0);

}//pc_printf


//初期化
void setup()
{

  //ポートをhiにする 初期化
  pinMode(in7, OUTPUT);
  DW(in7, HIGH);

  //I2Cの初期化
  Wire.begin(PA12, PA11); //stm32g031

} //setup


//メインループ
void loop()
{

  char data_read[8]; //バッファー
  int  l;
  unsigned char b = 200;

  //読み込み
  Wire.requestFrom(8, 1);

  while(Wire.available())  {    // 要求より短いデータが来る可能性あり
    b = Wire.read();       // 1バイトを受信
  }//while

  if( b <= 139 ) {
    l = b + 60;
  } else {
    l = ((int)(b - 140 + 20)) * 10;
  }

  //前の0を削る
  //  012  add
  // [123] data
  int yy;
  if      (l >= 100) {yy = 0;}
  else if (l >= 10)  {yy = 1;}
  else               {yy = 2;}

  //表示
  data_read[3] = 0;
  data_read[2] = '0' + (  l - (DIV10(l) * 10)  );  // '0'+(b%10)
  l = DIV10(l);
  data_read[1] = '0' + (  l - (DIV10(l) * 10)  );  // '0'+(b%10)
  data_read[0] = '0' +  DIV10(l);                  // '0'+(s/10)

  pc_printf("800,");

  pc_printf( ((char *)(data_read + yy )) ); //031

  pc_printf(",0");
  pc_printf("\r\n");

  delay(10); // 1/100秒の待ち

} //loop





```