目的
adcのテスト用
どうしてこうなったかは、6-10,10-20,20-80を参考

#include <Wire.h>

//STM32G031J6M6 i2cピンの定義
#define sdaPin PA12    // ArduinoA4
#define sclPin PA11    // ArduinoA5

//MCP3425A0T-E/CHのアドレス
#define ADD 0x68

//#define in7 1 //uno
#define in7      PB7  // 1pin

#define DW   digitalWrite

//#define UART_DELAY 832 //  1200bps ok 031
#define UART_DELAY 102   //  9600bps ok 031

//10の割り算 0から1028までは、正しい。主に0から999
//#define DVI10(n) ((n*205)>>11)

//16ビットadcの4ビットの変換テーブル
#define ADC4BIT { 0   , 62 ,125 ,187 ,250 ,312 ,375 ,437 ,500 ,562 ,625 ,687 ,750 ,812 ,875 ,937 }

//仮想シリアルへの一文字出力 9600bps
int pc_putc(char ch) {
  
  DW(in7, HIGH);
  
    //q_st =  micros(); //debug

  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);
  
    //q_et =  micros(); //debug 引いた数が0で1041usなら正解
  
  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 ++);
        //Serial.print( *str1 ++ ); //uno

    } //while

    //戻り値
    return(0);
}//pc_printf

//0から999まで文字列に変換
char ch_hex_a_b[5];
char *ch_hex_a(int l_num)
{
  int a,b,c;
  
  b=l_num/10;
  c=l_num-(b*10); //1の桁
  a=b/10;         //100の桁
  b=b-(a*10);     //10の桁
  
  ch_hex_a_b[0] = '0' + a;
  ch_hex_a_b[1] = '0' + b;
  ch_hex_a_b[2] = '0' + c;
  ch_hex_a_b[3] = 0;

  return(ch_hex_a_b);
}//ch_hex_a


void setup()
{
  //ポートをhiにする 初期化
  pinMode(in7, OUTPUT);
  DW(in7, HIGH);
  delayMicroseconds(UART_DELAY*10);

  //while(1){pc_putc('A');delay(1000);} //debug
  //pc_printf("\r\nSTART\r\n"); //debug

  //Wire.begin();         //i2cの初期化 uno
  Wire.begin(sdaPin,sclPin); //STM32G031J6M6

  //Serial.begin(9600);

    // 7 *(1)待ち
    // 6 *(0)
    // 5 *(0)
    // 4 (0)ワンショット,*(1)連続
    // 3 | (00)12ビット,(01)14ビット
    // 2 | *(10)16ビット
    // 1 I *(00)x1,(01)x2
    // 0 I (10)x4,(11)x8

  //初期値の書き込み
  Wire.beginTransmission(ADD);
    Wire.write(0b10011000); //16bit 15sps PGA x1
  Wire.endTransmission();

} //setup

int read_data()
{
  //2文字の読み込み
  Wire.requestFrom(ADD, 2);

  //戻し
  return ( (Wire.read() << 8 ) + Wire.read() );
}//read_data


int s;   //101
int ii;     //ループカウンタ
int jj;     //ループカウンタ
int bit4[]=ADC4BIT;

float Voltage;     //電圧
float ir_length;   //長さ

void loop()
{
  s = read_data();
  //s = (65536/2)-1;
  //s = 65536/4;

char *gk;

ii=(s >> 4);
if     ( ii >= 2000 ) { ii = ii - 2000; gk="2.";  jj=2;  }
else if( ii >= 1000 ) { ii = ii - 1000; gk="1.";  jj=1;  }
else                  {                 gk="0.";  jj=0;  }

  //Serial.print( gk ); //uno
  //pc_printf( gk ); //debug_p

  //Serial.print( ch_hex_a( ii ) ); //uno
  //pc_printf( ch_hex_a( ii ) ); //debug_p
  
  s = bit4[ s & 0xf ];
  //Serial.print( ch_hex_a( s ) ); //uno
  //pc_printf( ch_hex_a( s ) ); //debug_p

  //pc_printf( "," ); //debug_p

  Voltage=jj + (  (float)(ii) / 1000.0  ) + (  (float)(s) / 1000000.0  );

//d  String thisString2 = String(Voltage);     // debug_o
//d  pc_printf( (char *)thisString2.c_str() ); // debug_o
//d  pc_printf( "," );                         // debug_o

//start 変換 変換 変換 変換 変換 変換 

  if (Voltage >= 0 && Voltage <= 0.4)   {Voltage = 0.4;}
  if (Voltage >= 3.12 && Voltage <= 5.0) {Voltage = 3.12;}

 if         (Voltage >= 0.4 && Voltage <= 1.3 ) { //80-20

 ir_length = 1.0/ ( 0.0125 + ( ( Voltage - 0.4) * (0.0375/0.9) ) );

  } else if (Voltage >= 1.3 && Voltage <= 2.3 ) { //20-10

ir_length = 1/ ( 0.05 + ( ( Voltage - 1.3) * 0.05 ) );

  } else if (Voltage >= 2.3 && Voltage <= 2.75)  { //10-8

    ir_length = 1.0/ ( 0.1 + ( ( Voltage - 2.3) * (0.025/0.45) ) );

  } else if (Voltage >= 2.75 && Voltage <= 2.98) { //8-7

    ir_length = 1.0/ ( 0.125 + ( ( Voltage - 2.75) * (0.0179/0.23) ) );

  } else if (Voltage >= 2.98 && Voltage <= 3.12) { //7-6

    ir_length = 1.0/ ( 0.1429 + ( ( Voltage - 2.98) * (0.0238/0.14) ) );

  }

//end 変換 変換 変換 変換 変換 変換 

  //pc_printf( "," ); //debug_i
  String thisString3 = String(ir_length);
  pc_printf( (char *)thisString3.c_str() );

  
  //Serial.println(""); //uno
  pc_printf("\r\n");



  delay(1000);
} //loop