Byte truncation other than void * on Arduino

Question

I hope someone helps me diagnose this strange behavior that I am experiencing. I program Arduino Due and using Adafruit FONA modem . This code sends an array of bytes to send by modem. sendDataaccepts unsigned char[]that I drop on void*. data_len- the number of bytes written to the buffer, and not the size of the buffer itself.

The panel I'm working with doesn't use printf / sprintf to print to stdout. Instead, this is done with Serial.printand Serial.println. Serialhere is the Arduino class, not the standard C ++ class. sprintf_ByteArrayI wrote to check the contents of a byte buffer with results displayed as hexadecimal bytes.

As I said, my ultimate goal is to write data to the modem. This is done in calls fonaSerial->printlnand fonaSerial->write. First, a modem command is issued with the size of the data to be written. The second writes data.

But I'm experiencing something sharp. The print result dataand String messageis shown below. Optional for me, messagecontains only the last 119 bytes data. At first, this did not surprise me, because it datacontains empty bytes, and I suggested that it was somehow to blame. But messageactually contains empty bytes! And I would expect it messageto represent the first N bytes in data, up to the first null byte.

Finally: I end up datasending datain uint8_t*and switching to fonaSerial->write. I originally went through String, but after I had problems with casting, I decided to try this alternative approach. Then I send this data to the server on which I am running. The server receives only a 119 byte payload.

For recording, earlier I successfully sent a smaller payload. I have no idea what I'm doing now, which is causing the problem.

bool sendData(void *data, size_t data_len) {    
  char tmp[1024] = {0};
  Serial.print("data_len=");Serial.println(data_len);
  sprintf_ByteArray(tmp, (unsigned char*) data, data_len);
  Serial.print("Payload (void*)=");Serial.println(tmp);
  String message = (const char*) data;
  Serial.print("Payload (String)=");Serial.println(message);

  fonaSerial->print(F("AT+CIPSEND="));
  fonaSerial->println(data_len);

  fona.readline(3000);
  fonaSerial->write((uint8_t*) data, data_len);
  fonaSerial->flush();

  fona.readline(3000); // wait up to 3 seconds to send the data
  Serial.print (F("\t<--- ")); Serial.println(fona.replybuffer);

  return (strcmp(fona.replybuffer, "SEND OK") == 0);
}

Payload (void*)= 8a a5 62 69 64 00 69 63 6f 6e 64 69 74 69 6f 6e 01 67 62 61 74 74 65 72 79 18 1d 65 73 74 61 74 65 02 69 74 69 6d 65 73 74 61 6d 70 19 0f 95 a5 62 69 64 01 69 63 6f 6e 64 69 74 69 6f 6e 01 67 62 61 74 74 65 72 79 18 42 65 73 74 61 74 65 62 69 74 69 6d 65 73 74 61 6d 70 19 0f 97 a5 62 69 64 02 69 63 6f 6e 64 69 74 69 6f 6e 00 67 62 61 74 74 65 72 79 18 29 65 73 74 61 74 65 06 69 74 69 6d 65 73 74 61 6d 70 19 0f 98 a5 62 69 64 03 69 63 6f 6e 64 69 74 69 6f 6e 01 67 62 61 74 74 65 72 79 18 26 65 73 74 61 74 65 01 69 74 69 6d 65 73 74 61 6d 70 19 0f 99 a5 62 69 64 04 69 63 6f 6e 64 69 74 69 6f 6e 01 67 62 61 74 74 65 72 79 18 2f 65 73 74 61 74 65 62 69 74 69 6d 65 73 74 61 6d 70 19 0f 9a a5 62 69 64 05 69 63 6f 6e 64 69 74 69 6f 6e 01 67 62 61 74 74 65 72 79 18 1d 65 73 74 61 74 65 06 69 74 69 6d 65 73 74 61 6d 70 19 0f 9c a5 62 69 64 18 42 69 63 6f 6e 64 69 74 69 6f 6e 18 75 67 62 61 74 74 65 72 79 18 69 65 73 74 61 74 65 18 6c 69 74 69 6d 65 73 74 61 6d 70 1a 67 6e 69 64 a5 62 69 64 18 20 69 63 6f 6e 64 69 74 69 6f 6e 18 6c 67 62 61 74 74 65 [72 79 18 6f 65 73 74 61 74 65 18 74 69 74 69 6d 65 73 74 61 6d 70 1a 00 6e 39 20 a5 62 69 64 62 69 63 6f 6e 64 69 74 69 6f 6e 00 67 62 61 74 74 65 72 79 18 40 65 73 74 61 74 65 74 69 74 69 6d 65 73 74 61 6d 70 19 0f a0 a5 62 69 64 74 69 63 6f 6e 64 69 74 69 6f 6e 00 67 62 61 74 74 65 72 79 18 43 65 73 74 61 74 65 74 69 74 69 6d 65 73 74 61 6d 70 19 0f a1]

length 471

Payload (String)= 72 79 18 6f 65 73 74 61 74 65 18 74 69 74 69 6d 65 73 74 61 6d 70 1a 00 6e 39 20 a5 62 69 64 62 69 63 6f 6e 64 69 74 69 6f 6e 00 67 62 61 74 74 65 72 79 18 40 65 73 74 61 74 65 74 69 74 69 6d 65 73 74 61 6d 70 19 0f a0 a5 62 69 64 74 69 63 6f 6e 64 69 74 69 6f 6e 00 67 62 61 74 74 65 72 79 18 43 65 73 74 61 74 65 74 69 74 69 6d 65 73 74 61 6d 70 19 0f a1

length 119