UnitV2で顔認識結果の処理

#include <M5Stack.h>
#include <arduinojson.h>
#include <softwareserial.h>

SoftwareSerial Grove(22, 21);     // define rx/tx connecting to the UnitV2 camera
                                  // SoftwareSerial(rxPin, txPin, inverse_logic)

float x;
int y;
long k;
char data[1000];

void setup() {
  M5.begin();
  M5.Lcd.setCursor(20, 40);
  M5.Lcd.setTextSize(2);
  M5.Speaker.begin(); 
  Serial.begin(115200);
  Grove.begin(115200);
  M5.Lcd.print("--initialized--");      // display M5 Lcd message
  M5.Lcd.setCursor(20, 70);
  M5.Lcd.print("Face recongition");
}


void loop_(){

  if(Grove.available()) {
    String recvStr = Grove.readStringUntil('\n');
    if(recvStr[0] == '{'){
      Serial.print(recvStr);
    }
  }
}

void readJSON(void){
  String recvStr = Grove.readStringUntil('\n');
  StaticJsonDocument<1024> doc;
  DeserializationError error = deserializeJson(doc, recvStr);

  if (error) {
    Serial.print(F("deserializeJson() failed: "));
    Serial.println(error.f_str());
    return;
  }

  x = doc["face"][0]["match_prob"];
}

void loop(){
  M5.Speaker.mute();
  if(Grove.available()) {
    readJSON();
    Serial.println(x);
    if (x > 0.7f)
    {
      M5.Speaker.setVolume(3);
      M5.Speaker.beep();
      delay(200);     
    }
  }
}