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» SD 02: Write file

This example shows how to turn on the SD card. Write data in SD file indicating the position to write.

Required Materials

1 x Waspmote
1 x Battery
1 x SD card
1 x MiniUSB wire

Notes

* Remember that only 8.3 SHORT FILE NAME are valid for files and directories
- Make sure Waspmote is switched off before inserting or removing the SD card. Otherwise, the SD card could be damaged.
- Waspmote must not be switched off or reseted while there are ongoing read or write operations in the SD card. Otherwise, the SD card could be damaged and data could be lost. If you suspect that there may be some ongoing SD operations, wait a while until they are completed.
- This example can be executed in Waspmote v12 and Waspmote v15

Code

/*  
 *  ------ [SD_02] - Write data to a SD file -------- 
 *  
 *  Explanation: Turn on the SD card. Write data in SD file
 *  indicating the position to write.
 *  
 *  Copyright (C) 2016 Libelium Comunicaciones Distribuidas S.L. 
 *  http://www.libelium.com 
 *  
 *  This program is free software: you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation, either version 3 of the License, or 
 *  (at your option) any later version. 
 *  
 *  This program is distributed in the hope that it will be useful, 
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 *  GNU General Public License for more details. 
 *  
 *  You should have received a copy of the GNU General Public License 
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>. 
 *  
 *  Version:           3.0
 *  Design:            David Gascón 
 *  Implementation:    Yuri Carmona
 */

// define file name: MUST be 8.3 SHORT FILE NAME
char filename[]="FILE2.TXT";

// define hexadecimal data
uint8_t data[10]={0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0xAA,0xAA};

// define variable
uint8_t sd_answer;


void setup()
{
  // open USB port
  USB.ON();
  USB.println(F("SD_2 example"));
  
  // Set SD ON
  SD.ON();
    
  // Delete file
  sd_answer = SD.del(filename);
  
  if( sd_answer == 1 )
  {
    USB.println(F("file deleted"));
  }
  else 
  {
    USB.println(F("file NOT deleted"));  
  }
    
  // Create file
  sd_answer = SD.create(filename);
  
  if( sd_answer == 1 )
  {
    USB.println(F("file created"));
  }
  else 
  {
    USB.println(F("file NOT created"));  
  } 
}


void loop()
{     
  
  // 1 - It writes “hello” in file at position 0    
  sd_answer = SD.writeSD(filename,"hello", 0);
  
  if( sd_answer == 1 ) 
  {
    USB.println(F("\n1 - Write \"hello\" in file at position 0 ")); 
  }
  else
  {
    USB.println(F("\n1 - Write failed"));  
  }
  
  // show file
  SD.showFile(filename);
  delay(1000);
  

  
  // 2 - It writes “goodbye” in file at position 5
  sd_answer = SD.writeSD(filename,"goodbye", 5);
  
  if( sd_answer == 1 ) 
  {
    USB.println(F("\n2 - Write \"goodbye\" in file at position 5"));
  }
  else
  { 
    USB.println(F("\n2 - Write failed")); 
  }
  
  // show file
  SD.showFile(filename);
  delay(1000);



  // 3 - It writes “hel” in file at position 10 indicating 3-byte length
  sd_answer = SD.writeSD(filename,"hello", 10, 3);
  
  if( sd_answer == 1 ) 
  {
    USB.println(F("\n3 - Write \"hel\" in file at position 10 indicating 3-byte length"));
  }
  else
  {
    USB.println(F("\n3 - Write failed"));   
  }
 
   // show file
  SD.showFile(filename);
  delay(1000);
   
   
   
  // 4 - It writes hexadecimal data indicating the length to write
  sd_answer = SD.writeSD(filename, data, 0, 3);
  
  if( sd_answer == 1 ) 
  {
    USB.println(F("\n4 - Write hexadecimal data indicating 3 bytes to be written (offset=0)"));
  }
  else
  {
    USB.println(F("\n4 - Write failed"));  
  }
  
  // show file
  SD.showFile(filename);
  delay(1000);
   
   
   
  // 5 - It writes hexadecimal data
  // End of data array is defined by 0xAAAA
  sd_answer = SD.writeSD(filename, data, 0);
  
  if( sd_answer == 1 )
  {
    USB.println("\n5 - Write array of bytes (offset=0). End of 'data' array is defined by 0xAAAA");
  }
  else
  {
    USB.println("\n5 - Write failed");
  }

  // show file
  SD.showFile(filename);   
  USB.println(F("\n***************************"));
  delay(10000);
}


Output

H#
SD_2 example
file deleted
file created

1 - Write "hello" in file at position 0

-------------------
hello
-------------------

2 - Write "goodbye" in file at position 5

-------------------
hellogoodbye
-------------------

3 - Write "hel" in file at position 10 indicating 3-byte length

-------------------
hellogoodbhel
-------------------

4 - Write hexadecimal data indicating 3 bytes to be written (offset=0)

-------------------
012logoodbhel
-------------------

5 - Write array of bytes (offset=0). End of 'data' array is defined by 0xAAAA

-------------------
01234567dbhel
-------------------

***************************

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