Test_CheapGPS.ino

#include <M5Stack.h>

HardwareSerial mySerial(2); // RX, TX

void setup() {
  Serial.begin(115200);
  M5.begin();

  M5.Lcd.setTextSize(1);
  M5.Lcd.setTextColor(WHITE, BLACK);

  mySerial.begin(9600);
}

char line[201];
int p = 0;

void loop() {
  if (mySerial.available()) {
    int c = mySerial.read();
    if (c == 13) {
      mySerial.read();
      line[p] = 0;
      Serial.print(line);
      if (strstr(line, "GNRMC")) {
        M5.Lcd.setCursor(0, 30);
        M5.Lcd.printf(line);
        Serial.println("<--------------------");
      } else {
        Serial.println("");
      }
      p = 0;
    } else {
      line[p++] = c;
    }
  }
}