JsonParserExample_test_1.ino

// Copyright Benoit Blanchon 2014
// MIT License
//
// Arduino JSON library
// https://github.com/bblanchon/ArduinoJson

// test environment
// arduino uno r3
// arduino ide 1.06
// from ArduinoJson ChangeLOg.md
//Arduino JSON: change log
//========================

//v4.2
//----
//
/***********************************
Possible memory leak or issue during parse:
Look at the messages on serial monitor which say:
  Serial.print(F("json buffer contents before parse: "));
  Serial.println(json);
  // copy the char array to a temp buffer
  // because it appears that ArduinoJson lib somehow truncates it
  snprintf_P(espbuffer, (sizeof(espbuffer)), PSTR("%s"), json);  
  Serial.print(F("json buffer contents in temp buffer before parse: "));
  and  
  Serial.print(F("json temp buffer contents after parse: "));   
  Serial.println(espbuffer);
  
  after the parse the espbuffers' contents appear to be truncated.
  
  also:
  with StaticJsonBuffer<300> jsonBuffer;
  declared as a global variable, the parse reports failure after the 4th or 5th time thru the loop.
  
  with it declared inside the parse function ( parseTestDataJSON)
  no reported parse failures are seen but the 
  espbuffer is still appears to be truncated.
***********************************/
#include <ArduinoJson.h>  
//StaticJsonBuffer<300> jsonBuffer;

const char AppVer[6] = "V1.01";

#define ESP_BUFFER_SIZE 300
char espbuffer[ESP_BUFFER_SIZE];

char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";

const int  MAXARRAYSIZE   = 80;                 // 63 chars plus 1 for \0 terminator
const int  MAXNUMCHARS    = MAXARRAYSIZE - 1;   // leave room for null terminator
char  tempoutString1[MAXARRAYSIZE];             // for formatting data

void setup() 
{
  Serial.begin(115200);
  Serial.flush();
  showAppVersion();
  showFreeSram();

  /*******************************************
  JsonObject& root = jsonBuffer.parseObject(json);
  if (!root.success()) 
  {
    Serial.println("parseObject() failed");
    return;
  }

  const char* sensor = root["sensor"];
  long time = root["time"];
  double latitude = root["data"][0];
  double longitude = root["data"][1];

  Serial.println(sensor);
  Serial.println(time);
  Serial.println(latitude, 6);
  Serial.println(longitude, 6);
  **********************************************/
}

void loop() 
{
  showFreeSram();
  parseTestDataJSON(json);
  delay(10000);   // ten second delay
}


boolean parseTestDataJSON(char* json)          // for some reason the compiler.linker/preprocessor will not accept a define for buffer size
{  
  StaticJsonBuffer<300> jsonBuffer; 
  
  Serial.print(F("json buffer contents before parse: "));
  Serial.println(json);
  // copy the char array to a temp buffer
  // because it appears that ArduinoJson lib somehow truncates it
  snprintf_P(espbuffer, (sizeof(espbuffer)), PSTR("%s"), json);  
  Serial.print(F("json buffer contents in temp buffer before parse: "));  
  Serial.println(espbuffer);
  
  JsonObject& root = jsonBuffer.parseObject(espbuffer); 
  Serial.print(F("json temp buffer contents after parse: "));   
  Serial.println(espbuffer);
  
  if (!root.success())
  {
    Serial.println("parseObject() failed");
    return false;
  }  
  const char* sensor = root["sensor"];
  long time = root["time"];
  double latitude = root["data"][0];
  double longitude = root["data"][1];  
  
  char myBuf1[20] = ""; 
  char myBuf2[20] = "";

  snprintf_P(tempoutString1, (MAXARRAYSIZE - 1), PSTR("Sensor: %s"), sensor);
  Serial.println(tempoutString1);

  snprintf_P(tempoutString1, (MAXARRAYSIZE - 1), PSTR("Time: %d"), time);
  Serial.println(tempoutString1);
  
  snprintf_P(tempoutString1, (MAXARRAYSIZE - 1), PSTR("Latitude: %s, Longitude: %s"), ftoa(myBuf1, latitude, 2), ftoa(myBuf2, longitude, 2));
  Serial.println(tempoutString1);
}


//******** Utilities ************************
void showAppVersion()
{
  Serial.print(F("App Version: "));
  Serial.println(AppVer);
  Serial.print(F("Filename ... "));
  Serial.println(__FILE__);  // print out the sketches file name
  Serial.print(F("Compile Date and Time: "));
  Serial.print(__DATE__);
  Serial.print(F(" "));
  Serial.println(__TIME__);
}
int freeRam()
{
  extern int __heap_start, *__brkval;
  int v;
  return (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval);
}


void showFreeSram()
{
  Serial.print(F("Free Ram: "));
  Serial.println(freeRam());
}


char *ftoa(char *a, double f, int precision)
{
  long p[] = {0,10,100,1000,10000,100000,1000000,10000000,100000000};

  char *ret = a;
  long heiltal = (long)f;
  itoa(heiltal, a, 10);
  while (*a != '\0') a++;
  *a++ = '.';
  long desimal = abs((long)((f - heiltal) * p[precision]));
  itoa(desimal, a, 10);
  return ret;
}

//*********** end utility stuff *****