Lately, in the field of electronics use of GSM modules has been incorporated in almost 50% of the circuits for the wide range of benefits it offers. The project “GSM-based notice board Using AT89c52” also takes an advantage of the GSM module to design an electronics notice board. Being wireless, it avoids the requirement of messy wires for circuit design with LCD interfacing. It consumes less power and is easy to operate. And the main point is that it is portable. Who would deny such a circuit over a maze of wired circuitry?
Circuit Description of GSM based notice board Using AT89c52
The project is applicable almost everywhere. It can be used in bus stations, railway stations, parks, etc to display messages wirelessly. Even in colleges and organizations, the benefits of the circuit can be fully enjoyed.
GSM module stands out as the heart of the project. It is accompanied by a 20×4 LCD to display information on the notice board. GSM modem is used for receiving and sending SMS. When a certified user wants to display a notice/message on the notice board, the user will send SMS from a verified mobile number and then the SMS thus received is displayed on LCD as a piece of useful information.
This project also includes some security features as it allows only verified users to access the LCD to supply the desired message. For this, the project compares the SMS sender’s number with a pre-configured number (hardcoded in source code). If the comparison gives positive output, then the message is directly displayed on the LCD. However, if the message is received from an unknown sender, a notification SMS is sent to a pre-configured number notifying invalid access to the board and taking necessary actions.
The circuit is much simpler as it involves just reading and sending SMS using a GSM modem. For those people who have had problems regarding text reading in GSM-based projects, this might be a single step to achieve the expected outcome. It can hence be taken as basic learning GSM-based project.
Other projects designed using GSM Module, posted in bestengineeringprojects.com
- Car Lock System using Arduino and GSM
- GPS and GSM based Vehicle Tracking System
- Arduino Based Automatic Call Answering Machine
- Accident Detection and Alert System
PARTS LIST OF GSM BASED NOTICE BOARD USING AT89C52
| Resistors (all ¼-watt, ± 5% Carbon, Unless Mentioned Otherwise) |
| R1, R2 = 10 KΩ
VR1 = 1 KΩ |
| Capacitors |
| C1 = 10 µF/16V (Electrolytic Capacitor)
C2, C3 = 33 pF (Ceramic Disc) |
| Semiconductor |
| IC1 = AT89C52 (Microcontroller) |
| Miscellaneous |
| GSM Modem
LCD1 = LM044L (40*4) LCD XTAL1 = SW1 = Push-to-On Switch |
Source Code of the project “GSM based notice board Using AT89c52”
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C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 1 C51 COMPILER V8.05a, COMPILATION OF MODULE GSMNB_LCD OBJECT MODULE PLACED IN GSMNB_LCD.OBJ COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE GSMNB_LCD.c BROWSE DEBUG OBJECTEXTEND line level source 1 #include<reg51.h> 2 #include<string.h> 3 #include<absacc.h> 4 #include<stdlib.h> 5 #include<ctype.h> 6 #define buffer 110 7 8 sbit rs = P3^5; 9 sbit e = P3^4; 10 11 void display_msg(); 12 void delay(unsigned int i); 13 void lcdstr(unsigned char *s); 14 void lcdcmd(unsigned char val); 15 void lcddata(unsigned char val); 16 void lcdinit(); 17 void tx0(unsigned char); 18 void SMSString(unsigned char*text) ; 19 void init(); 20 void clear(void); 21 void read_notification(); 22 void clear_mybuff(); 23 void delete_msg(void); 24 void read_no(unsigned char msg_array[]); 25 void store_msg(unsigned char msg_array[]); 26 void password(); 27 void read_nd_check_password(unsigned char msg_array[]); 28 unsigned char abc,apt=0,count=0; 29 unsigned char idata msg1[buffer]; 30 unsigned char rec_no[10]; 31 unsigned char time_date[10]; 32 unsigned char code Response[] = "+CMTI"; 33 // Moblie no.of Owner 34 unsigned char code Mob_no[]= "98xxxxxxxx"; 35 unsigned char code Pass_array[]="1234"; 36 unsigned char MyBuff[20], k = 0; 37 bit flag1=0; 38 unsigned char store[10]; 39 bit NewMessage = 0; 40 bit TI_flag = 0; 41 bit flag=0; 42 bit No_correct=0; 43 44 void lcdstr(unsigned char *s) 45 { 46 1 unsigned int l,i; 47 1 l = strlen(s); // get the length of string 48 1 for(i=1;i<=l;i++) 49 1 { 50 2 lcddata(*s); // write every char one by one 51 2 s++; 52 2 } 53 1 } 54 void lcdcmd(unsigned char val) 55 { C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 2 56 1 57 1 P1=val; 58 1 rs=0; 59 1 e=1; 60 1 delay(1); 61 1 e=0; 62 1 return; 63 1 } 64 65 void delay(unsigned int i) 66 { 67 1 unsigned int k, l; 68 1 for(k=0;k<i;k++) 69 1 for(l=0;l<1000;l++); 70 1 } 71 void lcddata(unsigned char val) 72 { 73 1 74 1 P1=val; 75 1 rs=1; 76 1 e=1; 77 1 delay(1); 78 1 e=0; 79 1 return; 80 1 } 81 82 83 void lcdinit() 84 { 85 1 lcdcmd(0x38); // 2 lines 5x7 matrix. 86 1 delay(5); 87 1 lcdcmd(0x0c); // Display ON Cursor Blinking. 88 1 delay(5); 89 1 lcdcmd(0x01); // Clear Display Screen. 90 1 delay(5); 91 1 lcdcmd(0x06); // Increment Cursor. 92 1 delay(5); 93 1 94 1 } 95 96 void main () 97 { 98 1 99 1 //if u do not want to check "OK" response after each AT command then 100 1 //enable interrupt IE=0X90 ; after last AT command of 101 1 //SMSString( "AT+CMGR=1\r"); // AT command to read sms 102 1 //so after that u recieve a no of bytes from modile if u disable it then u do not reieve 103 1 //it even data comes 104 1 // unsigned char t; 105 1 106 1 clear(); 107 1 lcdinit(); 108 1 lcdcmd(0x80); 109 1 lcdstr("Welcome to GSM"); 110 1 lcdcmd(0xc0); 111 1 lcdstr("based Noticeboard"); 112 1 113 1 delay(10); 114 1 init(); 115 1 IT0 = 1; // Configure interrupt 0 for falling edge on /INT0 (P3.2) 116 1 SMSString("AT\r"); // AT commands to initialize gsm modem 117 1 delay(50); C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 3 118 1 119 1 SMSString( "ATe0\r"); // turn off echo 120 1 delay(50); 121 1 122 1 SMSString( "AT&W\r"); // save settings 123 1 delay(50); 124 1 125 1 SMSString( "AT+CMGF=1\r"); // select text mode for sms 126 1 delay(50); 127 1 128 1 SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms 129 1 while(1) 130 1 { 131 2 132 2 IE=0x91; 133 2 k=0; 134 2 delay(10); 135 2 flag=0; 136 2 while(!NewMessage); 137 2 { 138 3 IE=0X00; 139 3 delay(10); 140 3 NewMessage = 0; 141 3 read_notification(); 142 3 } 143 2 //New msg indication. 144 2 // +CMTI: "SM",3 145 2 } 146 1 147 1 } 148 void read_notification() 149 { 150 1 lcdcmd(0x01); //Clear LCD display. 151 1 clear(); 152 1 SMSString("AT+CMGR="); 153 1 tx0(MyBuff[12]); 154 1 SMSString("\r"); 155 1 IE=0x90; 156 1 delay(200); 157 1 read_no(msg1); 158 1 IE=0x00; 159 1 if(No_correct==1) 160 1 { 161 2 162 2 lcdcmd(0x80); 163 2 lcdstr("Message Received"); 164 2 if(!isalpha(msg1[59])) // checks for received msg is password or a actual msg(data). 165 2 { 166 3 read_nd_check_password(msg1); 167 3 168 3 } 169 2 else 170 2 { 171 3 store_msg(msg1); 172 3 password(); 173 3 flag1=1; 174 3 } 175 2 } 176 1 else 177 1 { 178 2 lcdcmd(0x01); 179 2 lcdcmd(0x80); C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 4 180 2 lcdstr("Msg frm Unknown"); 181 2 delay(1); 182 2 } 183 1 clear(); 184 1 185 1 if(MyBuff[12]>='9') //After 9 msgs recieved it clears the Msg index from SIM 186 1 { 187 2 delete_msg(); 188 2 } 189 1 190 1 clear_mybuff(); 191 1 192 1 return; 193 1 } 194 195 void read_nd_check_password(unsigned char msg_array[]) 196 { 197 1 if(Pass_array[0]==msg_array[59]&& 198 1 Pass_array[1]== msg_array[60]&& 199 1 Pass_array[2]==msg_array[61]&& 200 1 Pass_array[3]== msg_array[62]) 201 1 { 202 2 display_msg(); 203 2 } 204 1 else 205 1 { 206 2 SMSString("AT+CMGS=\"98xxxxxxxx\"\r"); 207 2 delay(1); 208 2 SMSString("Password Incorrect!!"); 209 2 tx0(0x1A); // Ctrl+z 210 2 delay(10); 211 2 } 212 1 return; 213 1 } 214 void password() 215 { 216 1 SMSString("AT+CMGS=\"98xxxxxxxx\"\r"); 217 1 delay(1); 218 1 SMSString("Send Your 4 Digit Password"); 219 1 tx0(0x1A); // Ctrl+z 220 1 delay(10); 221 1 return; 222 1 } 223 224 void store_msg(unsigned char msg_array[]) 225 { 226 1 unsigned char i,j; 227 1 i=59; 228 1 j=0; 229 1 while(msg_array[i]!='\r') 230 1 { 231 2 store[j]= msg_array[i]; 232 2 i++; 233 2 j++; 234 2 } 235 1 //store[j]='!'; 236 1 237 1 return; 238 1 } 239 240 void display_msg() 241 { C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 5 242 1 lcdcmd(0x01); 243 1 lcdcmd(0x80); 244 1 lcdstr("Received Msg"); 245 1 delay(1); 246 1 lcdcmd(0xc0); 247 1 lcdstr(store); 248 1 return; 249 1 } 250 void delete_msg(void) 251 { 252 1 SMSString("AT+CMGD=8\r"); 253 1 delay(1); 254 1 SMSString("AT+CMGD=7\r"); 255 1 delay(1); 256 1 SMSString("AT+CMGD=6\r"); 257 1 delay(1); 258 1 SMSString("AT+CMGD=5\r"); 259 1 delay(1); 260 1 SMSString("AT+CMGD=4\r"); 261 1 delay(1); 262 1 SMSString("AT+CMGD=3\r"); 263 1 delay(1); 264 1 SMSString("AT+CMGD=2\r"); 265 1 delay(1); 266 1 SMSString("AT+CMGD=1\r"); 267 1 delay(1); 268 1 return; 269 1 } 270 271 void init() 272 { 273 1 P0=0x00; 274 1 abc=0; 275 1 TL1=0XFD; //9600 @ 11.0592 276 1 TH1=0xFD; 277 1 TMOD=0x20; 278 1 SCON=0x50; 279 1 TR1=1; 280 1 } 281 void SMSString(unsigned char* text) //function to send SMS using GSM modem 282 { 283 1 while (*text) 284 1 { 285 2 tx0(*text++); 286 2 } 287 1 } 288 void tx0(unsigned char x) //send data to serial port 0 289 { 290 1 EA=0; 291 1 SBUF=x; 292 1 while(TI==0); 293 1 TI=0; 294 1 EA=1; 295 1 } 296 void serial () interrupt 4 { 297 1 unsigned char ch; 298 1 if(RI){ 299 2 ch = SBUF; //character is read 300 2 RI = 0; //clear flag 301 2 if((ch == Response[k]) || (k > 4)) 302 2 { 303 3 if(ch != 0x0D) // 0x0D means data received.. C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 6 304 3 { 305 4 MyBuff[k++] = ch; 306 4 } 307 3 else 308 3 { 309 4 MyBuff[k] = '\0'; 310 4 NewMessage = 1; 311 4 k = 0; 312 4 } 313 3 } 314 2 else 315 2 { 316 3 msg1[abc]=ch;//received msg is stored. 317 3 abc++; 318 3 k = 0; 319 3 } 320 2 } 321 1 } 322 323 void clear_mybuff() 324 { 325 1 unsigned int a; 326 1 for(a=0;a<25;a++) 327 1 MyBuff[a]=0x00; 328 1 } 329 void clear(void) 330 { 331 1 unsigned int a; 332 1 for(a=0;a<buffer;a++) 333 1 msg1[a]=0x00; 334 1 abc=0; 335 1 } 336 337 void read_no(unsigned char msg_array[]) // reads the no from received msg and compares it with stored ms -g, If found wrong then send a msg to owner. 338 { 339 1 unsigned char i; 340 1 if(Mob_no[0]==msg_array[23]&& 341 1 Mob_no[1]== msg_array[24]&& 342 1 Mob_no[2]==msg_array[25]&& 343 1 Mob_no[3]== msg_array[26]&& 344 1 Mob_no[4]==msg_array[27]&& 345 1 Mob_no[5]== msg_array[28]&& 346 1 Mob_no[6]==msg_array[29]&& 347 1 Mob_no[7]== msg_array[30]&& 348 1 Mob_no[8]==msg_array[31]&& 349 1 Mob_no[9]== msg_array[32]) 350 1 { 351 2 No_correct=1; 352 2 } 353 1 else // Sends a msg to stored no if some unauthoriesd tries to send a msg. 354 1 { 355 2 No_correct=0; 356 2 SMSString("AT+CMGS=\"98xxxxxxxx\"\r");//authorise number 357 2 delay(1); 358 2 SMSString("Msg from Unknown number:( "); 359 2 for(i=23;i<=32;i++) 360 2 { 361 3 tx0(msg_array[i]); 362 3 delay(0); 363 3 } 364 2 SMSString(") is received."); C51 COMPILER V8.05a GSMNB_LCD 01/16/2016 16:06:19 PAGE 7 365 2 tx0(0x1A); // Ctrl+z 366 2 delay(100); 367 2 } 368 1 return; 369 1 } MODULE INFORMATION: STATIC OVERLAYABLE CODE SIZE = 1189 ---- CONSTANT SIZE = 358 ---- XDATA SIZE = ---- ---- PDATA SIZE = ---- ---- DATA SIZE = 54 17 IDATA SIZE = 110 ---- BIT SIZE = 5 ---- END OF MODULE INFORMATION. Click here to download source code C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S) |
Myself Prateek…I m studying electronics engineering 2nd year…I want some topics or ideas regarding a mini project based on electronics…help me plzzz