CODEWITHSUNDEEP
c++stringarduino
Teodor Constantin Din
Teodor Constantin Din

Reputation: 21

Arduino print string via serial

I was coding a while when I noticed that arduino when it print data to "console", it print it perfectly, but, when I try to copy it, only copyes part of string. Is like there are invisible characters.

I can't paste the output because when I try to copy it, it don't copy full.

What I was trying to do is to get data from a Mifare card and make an json format to print it to console to comunicate with other program. All go well, until it print data.

Arduino code

  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_B, block, &key, &(mfrc522.uid));
  if (status != MFRC522::STATUS_OK) {
    return false;
  }

  status = mfrc522.MIFARE_Read(block, buffer1, &len);
  if (status != MFRC522::STATUS_OK) {
    return false;
  }

  String user;
  for (char c : buffer1) {
    if (c != '^') {
      user += c;
    } else break;
  }

  block = 2;
  len = 18;

  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_B, block, &key, &(mfrc522.uid));
  if (status != MFRC522::STATUS_OK) {
    return false;
  }

  status = mfrc522.MIFARE_Read(block, buffer1, &len);
  if (status != MFRC522::STATUS_OK) {
    return false;
  }

  String unicID;
  for (char c : buffer1) {
    if (c != '^') {
      unicID += c;
    } else break;
  }

  String dataSend = "{\"u\":\"" + String(user) + "\",\"i\":\"" + String(unicID) + "\"}º";
  Serial.println (dataSend);
  dataSend.replace("\n","");dataSend.replace("\t","");dataSend.replace("\r","");dataSend.replace(" ","");
  Serial.println (dataSend);


  if (dataSend.length() > 20) {
    for (int x = 0; x  < ((dataSend.length() / 20) +3); x++) {
      Serial.println(String(x*20) + " ---- "+ String((x+1)*20));

      Serial.println(String(dataSend.substring(x*20,(x+1)*20)));
      delay(100);
    }
  } else {
    Serial.println( dataSend);
  }
  mfrc522.PICC_HaltA();
  mfrc522.PCD_StopCrypto1();

The output should be this splited every 20 characters:

{"u":"teoDinqtepfhtpefhtpe4b","i":"qwertyuiopasdfgBp"}º

But I get:

0 ---- 20
{"u":"teoDinqtepfhtp
20 ---- 40
e
40 ---- 60
pasdfg
60 ---- 80

80 ---- 100

Is like there are magical characters or something similar. Here is an image because I can't copy the first full output after or before trying to format it to solve problem.

Console output

Upvotes: 0

Views: 232

Answers (1)

Teodor Constantin Din
Teodor Constantin Din

Reputation: 21

Mifare cards have a limitation of 16 bytes x block and you can't write on protected blocks like 0, 3, 6 etc.. The error was that I was writing 17 bytes instead of 16 bytes and that returns invisible / error charaters that can't be displayed

Upvotes: 1

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