mainc.c

/* ---------------------------------------------------------------------------
 * IOT device based on ATMEGA328P + SIM800L + DHT22
 * will send temperature and humidity reading over GPRS to thingspeak platform
 * readings every N minutes configurable
 * by Adam Loboda - adam.loboda@wp.pl
 * baudrate for SIM800L communication is 9600 bps
 * please configure SIM800L to fixed 9600 first by AT+IPR=9600 command 
 * to ensure stability ans save config via AT&W command
 *
 * in this version SIM800L radio is NOT switched OFF
 * instead only SIM800L SLEEP MODE is used to 
 * conserve battery power
 * ---------------------------------------------------------------------------
 */

#include <inttypes.h>
#include <stdio.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include <avr/sleep.h>
#include <avr/wdt.h>
#include <string.h>
#include <avr/power.h>

#define UART_NO_DATA 0x0100
// internal RC oscillator 8MHz with divison by 8 and U2X0 = 1, gives 0.2% error rate for 9600 bps UART speed
// and lower current consumption
// for 1MHz : -U lfuse:w:0x62:m     on ATMEGA328P
#define F_CPU 1000000UL

#define BAUD 9600
// formula for 1MHz clock and U2X0 = 1 double UART speed 
#define MYUBBR ((F_CPU / (BAUD * 8L)) - 1)


// DHT22 sensor settings

#define DHT_PIN            PB0

#define DHT_ERR_OK         (0)
#define DHT_ERR_TIMEOUT    (-1)

#define DHT_PIN_INPUT()    (DDRB &= ~_BV(DHT_PIN))
#define DHT_PIN_OUTPUT()   (DDRB |= _BV(DHT_PIN))
#define DHT_PIN_LOW()      (PORTB &= ~_BV(DHT_PIN))
#define DHT_PIN_HIGH()     (PORTB |= _BV(DHT_PIN))
#define DHT_PIN_READ()     (PINB & _BV(DHT_PIN))
#define DHT_TIMEOUT        (80)

// static text needed for SIM800L conversation

const char AT[] PROGMEM = { "AT\n\r" }; // wakeup from sleep mode
const char ISOK[] PROGMEM = { "OK" };
const char ISREG1[] PROGMEM = { "+CREG: 0,1" };  // registered in HPLMN
const char ISREG2[] PROGMEM = { "+CREG: 0,5" };  // registered in ROAMING NETWORK
const char SHOW_REGISTRATION[] PROGMEM = {"AT+CREG?\n\r"};
const char PIN_IS_READY[] PROGMEM = {"+CPIN: READY"};
const char PIN_MUST_BE_ENTERED[] PROGMEM = {"+CPIN: SIM PIN"};

const char SHOW_PIN[] PROGMEM = {"AT+CPIN?\n\r"};
const char ECHO_OFF[] PROGMEM = {"ATE0\n\r"};
const char ENTER_PIN[] PROGMEM = {"AT+CPIN=\"1111\"\n\r"};

// Definition of APN used for GPRS communication
// Please put correct APN, USERNAME and PASSWORD here appropriate for your Mobile Network provider.
// If no password and username delete the text between < and >
const char SAPBR1[] PROGMEM = {"AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"\r\n"};  
const char SAPBR2[] PROGMEM = {"AT+SAPBR=3,1,\"APN\",\"internet\"\r\n"};             // Put your mobile operator APN name here
const char SAPBR3[] PROGMEM = {"AT+SAPBR=3,1,\"USER\",\"<MyUsername>\"\r\n"};    // Put your mobile operator APN USERNAME here if any
const char SAPBR4[] PROGMEM = {"AT+SAPBR=3,1,\"PWD\",\"<MyPassword>\"\r\n"};     // Put your mobile operator APN PASSWORD here if any
// PDP context commands
const char SAPBROPEN[] PROGMEM = {"AT+SAPBR=1,1\r\n"};      // open IP bearer
const char SAPBRQUERY[] PROGMEM = {"AT+SAPBR=2,1\r\n"};     // query IP bearer
const char SAPBRCLOSE[] PROGMEM = {"AT+SAPBR=0,1\r\n"};     // close bearer 
const char SAPBRSUCC[] PROGMEM = {"+SAPBR: 1,1"};           // bearer was succesfull we are not checking IP assigned

// Flightmode ON OFF - for network searching
const char FLIGHTON[] PROGMEM = { "AT+CFUN=4\r\n" };
const char FLIGHTOFF[] PROGMEM = { "AT+CFUN=1\r\n" };

// Sleepmode ON OFF
const char SLEEPON[] PROGMEM = { "AT+CSCLK=2\r\n" };
const char SLEEPOFF[] PROGMEM = { "AT+CSCLK=0\r\n" };

// Fix UART speed to 9600 bps
const char SET9600[] PROGMEM = { "AT+IPR=9600\r\n" };

// Save settings to SIM800L
const char SAVECNF[] PROGMEM = { "AT&W\r\n" };

// Disable SIM800L LED for further reduction of power consumption
const char DISABLELED[] PROGMEM = { "AT+CNETLIGHT=0\r\n" };

// HTTP communication with Thingspeak 
const char HTTPAPIKEY[] PROGMEM = { "XXXXXXXXXXXXXXX" };   // Put your THINGSPEAK API KEY HERE !!!
const char HTTPINIT[] PROGMEM = { "AT+HTTPINIT\r\n" };
const char HTTPPARA[] PROGMEM = { "AT+HTTPPARA=\"CID\",1\r\n" };
const char HTTPTSPK1[] PROGMEM = { "AT+HTTPPARA=\"URL\",\"http://" };
const char HTTPTSPK2[] PROGMEM = { "api.thingspeak.com/update?api_key=" };
const char HTTPTSPK3[] PROGMEM = { "&field1=" };
const char HTTPTSPK4[] PROGMEM = { "&field2=" };
const char HTTPTSPK5[] PROGMEM = { "\"\n\r" };
const char HTTPACTION[] PROGMEM = { "AT+HTTPACTION=0\r\n" };


#define BUFFER_SIZE 40
// buffers for number of phone, responses from modem, temperature & humidity texts
volatile static uint8_t response[BUFFER_SIZE] = "1234567890123456789012345678901234567890";
volatile static uint8_t response_pos = 0;
volatile static uint8_t dhttxt[6] = "00000\x00";
volatile static uint8_t buf[20];  // buffer to copy string from PROGMEM


// -------------------------------------------------------------------------------------------------------
// ---------------------------------------- DHT22  library CODE ------------------------------------------
// -------------------------------------------------------------------------------------------------------


void  dht_init(void)
{
   DHT_PIN_INPUT();
   DHT_PIN_HIGH();
}

static int8_t   dht_await_state(uint8_t state)
{
    uint8_t counter = 0;
    while ((!DHT_PIN_READ() == state) && (++counter < DHT_TIMEOUT)) 
     { 
     // Delay 1 cycles
     // 1us at 1.0 MHz CLOCK
     asm volatile (
        "    nop"	"\n"
        );
     };
    return counter;
}


int8_t dht_read(uint8_t *temperature_hi, uint8_t *temperature_lo, uint8_t *humidity_hi, uint8_t *humidity_lo)
{
    uint8_t i, j, data[5] = {0, 0, 0, 0, 0};

    // send start sequence 1 LOW pulse for 2 miliseconds
    DHT_PIN_OUTPUT();
    DHT_PIN_LOW();

    // Delay 20 000 cycles
    // 20ms at 1 MHz
    asm volatile (
         "    ldi  r18, 26"	"\n"
         "    ldi  r19, 249"	"\n"
         "1:  dec  r19"	"\n"
         "    brne 1b"	"\n"
         "    dec  r18"	"\n"
         "    brne 1b"	"\n"
          );

    DHT_PIN_HIGH();
    DHT_PIN_INPUT();

    // read response sequence - 1 pulse  as preparation before sending measurement
    if (dht_await_state(0) < 0) return DHT_ERR_TIMEOUT;
    if (dht_await_state(1) < 0) return DHT_ERR_TIMEOUT;
    if (dht_await_state(0) < 0) return DHT_ERR_TIMEOUT;
    

    // read data - 40 bits - HOGH pulse length goves info aboit 0s and 1s 
    for (i = 0; i < 5; ++i) {
        for (j = 0; j < 8; ++j) 
          {
         // wait for next BIT to come
         dht_await_state(1);
         // do left shift
         data[i] <<= 1;
         // received BIT is "1" if waiting for LOW longer than 28 microseconds - 
         // the value = 1 in comparision is experimental for 1MHz clock, 20 for 8MHz
         if (dht_await_state(0) > 1)  data[i] |= 1;   
          };
    };

    // check if checksum matches
    if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF) ) 
     { 
    *temperature_hi = data[2];
    *temperature_lo = data[3];
    *humidity_hi = data[0];
    *humidity_lo = data[1];

    }
    else
    {
    *temperature_hi = 0;
    *temperature_lo = 0;
    *humidity_hi = 0;
    *humidity_lo = 0;

    }; 

     
    return DHT_ERR_OK;
}



// ----------------------------------------------------------------------------------------------
// init_uart
// ----------------------------------------------------------------------------------------------
void init_uart(void) {
  // double speed by U2X0 flag = 1 to have 0.2% error rate on 9600 baud
 UCSR0A = (1<<U2X0);
  // set baud rate from PRESCALER
 UBRR0H = (uint8_t)(MYUBBR>>8);
 UBRR0L = (uint8_t)(MYUBBR);
 UCSR0B|=(1<<TXEN0); //enable TX
 UCSR0B|=(1<<RXEN0); //enable RX
  // set frame format for SIM808 communication
 UCSR0C|=(1<<UCSZ00)|(1<<UCSZ01); // no parity, 1 stop bit, 8-bit data 
}



// ----------------------------------------------------------------------------------------------
// send_uart
// Sends a single char to UART without ISR
// ----------------------------------------------------------------------------------------------
void send_uart(uint8_t c) {
  // wait for empty data register
  while (!(UCSR0A & (1<<UDRE0)));
  // set data into data register
  UDR0 = c;
}



// ----------------------------------------------------------------------------------------------
// receive_uart
// Receives a single char without ISR
// ----------------------------------------------------------------------------------------------
uint8_t receive_uart() {
  while ( !(UCSR0A & (1<<RXC0)) ) 
    ; 
  return UDR0; 
}


// ----------------------------------------------------------------------------------------------
// function to search RX buffer for response  SUB IN RX_BUFFER STR
// ----------------------------------------------------------------------------------------------
uint8_t is_in_rx_buffer(char *str, char *sub) {
   uint8_t i, j=0, k;
    for(i=0; i<BUFFER_SIZE; i++)
    {
      if(str[i] == sub[j])
     {
       for(k=i, j=0; str[k] && sub[j]; j++, k++)  // if NOT NULL on each of strings
            if(str[k]!=sub[j])   break; // if different - start comparision with next char
       // if(!sub[j]) return 1; 
        if(j == strlen(sub)) return 1;  // full substring has been found        
      }
     }
     // substring not found
    return 0;
}

 

// ----------------------------------------------------------------------------------------------
// uart_puts
// Sends a string.
// ----------------------------------------------------------------------------------------------
void uart_puts(const char *s) {
  while (*s) {
    send_uart(*s);
    s++;
  }
}



// ----------------------------------------------------------------------------------------------
// uart_puts_P
// Sends a PROGMEM string.
// ----------------------------------------------------------------------------------------------
void uart_puts_P(const char *s) {
  while (pgm_read_byte(s) != 0x00) {
    send_uart(pgm_read_byte(s++));
  }
}



// *********************************************************************************************************
// READLINE from serial port that starts with CRLF and ends with CRLF and put to 'response' buffer what read
// *********************************************************************************************************
uint8_t readline()
{
  uint16_t char1, i , wholeline ;
  // wait for first CR-LF or exit after timeout i cycles
   i = 0;
   wholeline = 0;
   response_pos = 0;
  //
   do {
      // read chars in pairs to find combination CR LF
      char1 = receive_uart();
      // if CR-LF combination detected start to copy the response
      if   (  char1 != 0x0a && char1 != 0x0d && response_pos < BUFFER_SIZE ) 
         { response[response_pos] = char1; 
           response_pos++;
         };

      if    (  char1 == 0x0a || char1 == 0x0d )              
         {  
           // if the line was received and this is only CR/LF ending :
           if (response_pos > 0) // this is EoL
               { response[response_pos] = NULL;
                 response_pos = 0;
                  wholeline = 1;  };
          // just skip this CRLF character and wait for valuable one
               
         };
      // if buffer is empty exit from function there is nothing to read from
      i++;
      } while ( wholeline == 0);

return 1;
}




/////////////////////////////////////////////////////////////////////////////////////////////////////////////
// delay procedure ASM based because _delay_ms() is working bad for 1 MHz clock MCU
/////////////////////////////////////////////////////////////////////////////////////////////////////////////

// delay partucular number of seconds 

void delay_sec(uint8_t i)
{
while(i > 0)
{
// Generated by delay loop calculator
// at http://www.bretmulvey.com/avrdelay.html
//
// Delay 1 000 000 cycles
// 1s at 1 MHz

asm volatile (
    "    ldi  r18, 6"	"\n"
    "    ldi  r19, 19"	"\n"
    "    ldi  r20, 174"	"\n"
    "1:  dec  r20"	"\n"
    "    brne 1b"	"\n"
    "    dec  r19"	"\n"
    "    brne 1b"	"\n"
    "    dec  r18"	"\n"
    "    brne 1b"	"\n"
    "    rjmp 1f"	"\n"
    "1:"	"\n"
);

i--;  // decrease another second

};    // repeat until i not zero

}


//////////////////////////////////////////
// SIM800L initialization procedures
//////////////////////////////////////////

// *********************************************************************************************************
// wait for first AT in case SIM800L is starting up
// *********************************************************************************************************
uint8_t checkat()
{
  uint8_t initialized2;

// wait for first OK while sending AT - autosensing speed on SIM800L, but we are working 9600 bps
// SIM 800L can be set by AT+IPR=9600  to fix this speed
// which I do recommend by connecting SIM800L to PC using putty and FTD232 cable

                 initialized2 = 0;
              do { 
               uart_puts_P(AT);
                if (readline()>0)
                   {
                    memcpy_P(buf, ISOK, sizeof(ISOK));                     
                   if (is_in_rx_buffer(response, buf) == 1)  initialized2 = 1;                  
                   };
               delay_sec(1);
               } while (initialized2 == 0);

        // send ECHO OFF
              uart_puts_P(ECHO_OFF);

             return initialized2;
}

// *********************************************************************************************************
// check if PIN is needed and enter PIN 1111 
// *********************************************************************************************************
uint8_t checkpin()
{

  uint8_t initialized2;
     // readline and wait for PIN CODE STATUS if needed send PIN 1111 to SIM card if required
                  initialized2 = 0;
              do { 
		delay_sec(2);
               uart_puts_P(SHOW_PIN);
                if (readline()>0)
                   {
                    memcpy_P(buf, PIN_IS_READY, sizeof(PIN_IS_READY));
                  if (is_in_rx_buffer(response, buf ) == 1)       initialized2 = 1;                                         
                    memcpy_P(buf, PIN_MUST_BE_ENTERED, sizeof(PIN_MUST_BE_ENTERED));
                  if (is_in_rx_buffer(response, buf) == 1)     
                        {  uart_puts_P(ENTER_PIN);   // ENTER PIN 1111
                           delay_sec(1);
                        };                  
                    };
                  
              } while (initialized2 == 0);
   return initialized2;
}


// *********************************************************************************************************
// check if registered to the network
// *********************************************************************************************************
uint8_t checkregistration()
{
  uint8_t initialized2, nbrminutes;
     // readline and wait for STATUS NETWORK REGISTRATION from SIM800L
     // first 2 networks preferred from SIM list are OK
                  initialized2 = 0;
                  nbrminutes = 0;
              do { 
                   delay_sec(3);
                 // check now if registered
                   uart_puts_P(SHOW_REGISTRATION);
                if (readline()>0)
                   {			   
                    memcpy_P(buf, ISREG1, sizeof(ISREG1));
                   if (is_in_rx_buffer(response, buf) == 1)  initialized2 = 1; 
                    memcpy_P(buf, ISREG2, sizeof(ISREG2));
                   if (is_in_rx_buffer(response, buf) == 1)  initialized2 = 1; 
                   }
                // if not registered or something wrong turn off RADIO for some time (battery) and turn it on again
                // this is not to drain battery in underground garage 
                else
                   {
                   delay_sec(1);
                   uart_puts_P(FLIGHTON);    // enable airplane mode - turn off radio for 3 minutes
                   delay_sec(60);                      
                   uart_puts_P(FLIGHTOFF);   // disable airplane mode - turn on radio and start to search for networks
                   delay_sec(60);                      
                 // give reasonable time to search for GSM network - 3 minutes is sufficient
                   };
                // end of DO loop
                } while (initialized2 == 0);

      return initialized2;
};
 


// *********************************************************************************************************
//
//                                                    MAIN PROGRAM
//
// *********************************************************************************************************

int main(void) {

  uint8_t initialized, attempt;

  uint8_t belowzero;
  uint8_t temperature_hi, temperature_lo, humidity_hi, humidity_lo;   // for temperature and humidity calculations
  uint16_t humidity = 0;
  uint16_t temperature = 0;
  uint16_t temporary;

  // initialize 9600 baud 8N1 RS232
  init_uart();

  // delay 10 seconds for safe SIM800L startup and network registration
  delay_sec(10);
          
  // try to communicate with SIM800L over AT
  checkat();
  delay_sec(2);

   // Fix UART speed to 9600 bps to disable autosensing
  uart_puts_P(SET9600); 
  delay_sec(2);

   // Turn off blinking LED on SIM800L module to conserve energy
  uart_puts_P(DISABLELED); 
  delay_sec(1);

   // Save settings to SIM800L
  uart_puts_P(SAVECNF);
  delay_sec(3);

   // check pin status, registration status and provision APN settings
  checkpin();
  delay_sec(2);
  // disable airplane mode - turn on radio and start to search for networks 
  uart_puts_P(FLIGHTOFF);   
  delay_sec(60);                      
  checkregistration();
  

  // neverending LOOP

       while (1) {

                // Create connection to GPRS network - 3 attempts if needed, if not succesfull restart the modem 
                 attempt = 0;
                // clear the loop flag 
                 initialized = 0;

  
                 do { 
                     // first check if network is available
                     checkregistration();
                     delay_sec(1);   
                     //and close the bearer first maybe there was an error or something
                     uart_puts_P(SAPBRCLOSE);
                     // connection to GPRS for AGPS basestation data - provision APN and username
                     delay_sec(5);
                     uart_puts_P(SAPBR1);
                     delay_sec(1);
                     uart_puts_P(SAPBR2);
                     // only if username password in APN is needed
                     delay_sec(1);
                     uart_puts_P(SAPBR3);
                     delay_sec(1);
                     uart_puts_P(SAPBR4);
            
                     // make GPRS network attach and open IP bearer
                      delay_sec(3);
                      uart_puts_P(SAPBROPEN);

                      // query PDP context for IP address after several seconds
                     // check if GPRS attach was succesfull, do it several times if needed
                      initialized = 0; 
                      delay_sec(5);
                      uart_puts_P(SAPBRQUERY);
                      if (readline()>0)
                            {
                              // checking for properly attached
                              memcpy_P(buf, SAPBRSUCC, sizeof(SAPBRSUCC));                     
                              if (is_in_rx_buffer(response, buf) == 1)  initialized = 1;
                              // other responses simply ignored as there was no attach
                            };
                       // increase attempt counter and repeat until not attached
                      attempt++;
                 } while ( (attempt < 3) && (initialized == 0) );
           

               // initialize DHT22 temperature & humidity sensor, we will get reading after 4 seconds
               dht_init();

               // initialize HTTP communication on SIM800L
               delay_sec(5);
               uart_puts_P(HTTPINIT);
               delay_sec(3);
               uart_puts_P(HTTPPARA);
               delay_sec(2);

               // begin sending to Thingspeak server 
               uart_puts_P(HTTPTSPK1);
               uart_puts_P(HTTPTSPK2);
               uart_puts_P(HTTPAPIKEY);
          
               // Now Read data from DHT22 sensor
               // read value from DHT22 sensor, humidity amd temperature are encoded on 16 bits each
               dht_read(&temperature_hi, &temperature_lo,  &humidity_hi, &humidity_lo);
               // Reading correction - check if most significant bit 15 is 1 from DHT 22 temperature reading
               // if so - temperature is below zero Celsius Degrees
               if (temperature_hi > 127)  
                    { // put 'minus' sign at the end instead of degrees, and clear first significant bit of temperature
                      temperature_hi = temperature_hi - 128;
                      belowzero = 45;  // MINUS character
                    } 
               else  
                    {
                      // do not change temperature reading, put 'zero' instead of minus sign
                      belowzero = 48;  // ZERO character
                    };

               // calculate 16bit temperature ( 10 times real temperature value)   
               temperature = ( temperature_hi * 256 ) + temperature_lo;
               // calculate 16bit Humidity ( 10 times real humidity value)   
               humidity = ( humidity_hi * 256 ) + humidity_lo;

               // send details about sensor status

              // calculate 3 digits for temperature
              uart_puts_P(HTTPTSPK3);  // put 'field1' in HTTP req
              dhttxt[0] = belowzero;
              dhttxt[1] = (temperature / 100) + 48;  // calculate ASCII code for digits
              temporary = temperature % 100; 
              dhttxt[2] = (temporary / 10) + 48;
              dhttxt[3] = 46 ;  // the DOT character
              dhttxt[4] = (temporary % 10) + 48; 
              uart_puts(dhttxt);   // send DHT22 temperature readings

              // calculate 3 digits for humidity
              uart_puts_P(HTTPTSPK4);  // put 'field2' in HTTP req
              dhttxt[0] = 48;  // empty 'zero'
              dhttxt[1] = (humidity / 100) + 48;
              temporary = humidity % 100; 
              dhttxt[2] = (temporary / 10) + 48;
              dhttxt[3] = 46 ;   // the DOT character
              dhttxt[4] = (temporary % 10) + 48; 
              uart_puts(dhttxt);   // send DHT22 humidity readings

              // send HTTP end sequence and make HTTP action
              uart_puts_P(HTTPTSPK5);  // put CRLF at the end
              delay_sec(2); 
              uart_puts_P(HTTPACTION);  // send prepared HTTP POST
              delay_sec(10);            // more seconds needed for stable TCP connection
 
              //and close the bearer 
              uart_puts_P(SAPBRCLOSE);
              delay_sec(5);
              // disable radio before SIM800L goes to sleep 
              //uart_puts_P(FLIGHTON);   
              //delay_sec(2);
              // enter SLEEP MODE of SIM800L before nex measurement to conserve energy
              uart_puts_P(SLEEPON); 
              delay_sec(11);
              // sleep 'N' minutes  before next measurement and GPRS connection.  
               for (attempt=1; attempt<120; attempt++)  delay_sec(60);
              // disable SLEEPMODE , turn on radio and start whole procedure again...                
              uart_puts_P(AT);
              delay_sec(1);
              uart_puts_P(SLEEPOFF);

        // end of neverending loop
        };

 
    // end of MAIN code 
}