mkrnb1500.ino get serial buffer to empty?

mkrnb1500.ino

/*

This code clears the u-blox on a MKR NB 1500 of all certificates.

*/

// baud rate used for both Serial ports
unsigned long baud = 115200;

// Must be large enough to capture all
// output.  Some responses are multiple lines
//
// Notes on Serial class/API:
// o  The serial class maintains a 64 byte buffer internally
// o  read() reads one byte at a time
//char pchBuffer[64];
char pchBuffer[2048];

unsigned long milliseconds = 1L; // NOTE: usage of L
unsigned long seconds = 1000L; // NOTE: usage of L
unsigned long minutes = seconds * 60;
unsigned long hours = minutes * 60;

void setup() {
  // NEVER EVER use RESET_N
  pinMode(SARA_RESETN, OUTPUT);
  digitalWrite(SARA_RESETN, LOW);

  // Send Poweron pulse
  pinMode(SARA_PWR_ON, OUTPUT);
  digitalWrite(SARA_PWR_ON, HIGH);
  delay(150);
  digitalWrite(SARA_PWR_ON, LOW);

  Serial.begin(baud);
  SerialSARA.begin(baud);

  // To avoid a wait for serial, just
  // delay long enough for a serial port to
  // be attached.
  for(int i=0; i<40; i++) {
    Serial.print("X");
    delay(150);
  }

  Serial.println("");

}


void write_cmd(char *pchBuffer) {
    int str_len;
    str_len = strlen(pchBuffer);
    // Write the command to the part
    while (SerialSARA.availableForWrite() < str_len) {
        delay(500);
    }
    // write to the part
    SerialSARA.write(pchBuffer);
}

// buffer is returned in provided buffer
// return code is the number of bytes valid 
// in buffer.  
int read_resp(char *resp) {

  char result;
  int index=0;

  // truncate string to start fresh
  resp[0]=0;

  Serial.print("how much is available? ");
  Serial.println(SerialSARA.available());

  // Read the results a byte at a time
  while (SerialSARA.available()) {
    result = SerialSARA.read();
    resp[index++]=result;
  }
  //SerialSARA.flush();
  return index;
}

int read_resp2(char *resp) {

  char result;
  int num_read=0;
  int num_avail;

  // truncate string to start fresh
  resp[0]=0;

  num_avail = SerialSARA.available();
  Serial.print("how much is available? ");
  Serial.println(num_avail);

  num_read = SerialSARA.readBytesUntil('\n', resp, 100);

  return num_read;
}
/*
 * Notes on the AT+USECMNG command
 * 
 * https://www.u-blox.com/en/docs/UBX-17003787
 *
 * Section 20.3 Data Security
 * Section 20.3.2 SSL/TLS certificates and private keys manager +USECMNG
 *
 * AT+USECMNG=<op code>,[type],[internal name],[param1],[param2]
 *
 * opcode  purpose
 *   0      import via serial IO
 *   1      import via file on FS
 *   2      remove cert/key         2,<type 0=cert, 1=key>,<internal name>
 *   3      list cert/key           3,[type],<internal name>
 *   4      retrieve MD5 of imported cert/key   4,<type><internal name>
 *
 */

void loop() {

  static bool first_time = true;

  int iRC;
  int iRC1;
  int iRC2;
  int iRC3;
  int iRC4;

  if (first_time) {
      // List all the certs and delete them
      strcpy(pchBuffer,"AT+USECMNG=3\r\n");
      write_cmd(pchBuffer);
      delay(20*milliseconds);
      first_time = false;
  }

  iRC = read_resp2(pchBuffer);
  Serial.print("Response len:  ");
  Serial.println(iRC);
  Serial.print("Response:  ");
  Serial.println(pchBuffer);


  //delay(20*milliseconds);
  //iRC = read_resp2(pchBuffer);
  //Serial.print("Response len:  ");
  //Serial.println(iRC);
  //Serial.print("Response:  ");
  //Serial.println(pchBuffer);


  //delay(20*milliseconds);
  //iRC2 = read_resp(pchBuffer);
  //Serial.print("Response:  ");
  //Serial.println(pchBuffer);
  //delay(20*milliseconds);
  //iRC3 = read_resp(pchBuffer);
  //Serial.print("Response:  ");
  //Serial.println(pchBuffer);
  //delay(2*seconds);
  //iRC4 = read_resp(pchBuffer);



  //Serial.print("Response len:  ");
  //Serial.println(iRC1);
  //Serial.print("Response len:  ");
  //Serial.println(iRC2);
  //Serial.print("Response len:  ");
  //Serial.println(iRC3);
  //Serial.print("Response len:  ");
  //Serial.println(iRC4);
  
  
  //Serial.print("Response:  ");
  //Serial.println(pchBuffer);
  //Serial.println("END STEP 0 --------------------");






//stop_here:
//  Serial.println("Halt");
//  while(true);
}