This document describes a project to control a GSM 1308 modem using a PIC16F877A microcontroller. The goals of the project were to improve an existing Flowcode program to allow the modem to function more like a general mobile phone. Key aspects included using the PIC16F877A and e-blocks components like an LCD board and keypad to send AT commands to the modem for calling, SMS sending and receiving. The programs were tested in Flowcode and shown to allow dialing, call answering, sending and receiving SMS via the modem and microcontroller interface.

1. GSM 1308 MODEM CONTROL
USING
PIC-16F877A MICROCONTROLLER

2. Presented by
Supervised By
Dr. A.K.M Fazlul Haque
Associate Professor
Department of ETE
Daffodil International
University
Sk.Mustafizur Rahman
ID: 082-19-930
Md. Moktarul Islam
ID: 082-19-938
Md.Emam-ul-Uddin
ID: 082-19-939

3. Aim of the Project:
Controlling the GSM 1308 modem using PIC16F877A by
improving the existing flowcode microcontroller program that
the modem can work as a more general mobile phone.

4. Content
 PIC16F877A Microcontroller
E-Blocks
GSM Modem Compiling Procedure
Flowcode Software
Main Programs
Result
Conclusion

5. PIC16F877A Microcontroller
The name PIC refers to a group of microcontrollers
This is a flexible 40 pin device. The
operating voltage of the microcontroller is
5V

6. Memory of 16F877A
Flash or EPROM: It is the memory where
the written program is stored.
RAM: It is the memory where the declared
'variables are stored.
EEPROM: It is the memory where the
variables can be permanently stored.

7. I/O Ports of 16F877A
PORT A : It is connected with Multiprogrammer
board
PORT C: It is Connected with RS232
Communicator
PORT D : It is connected with Keypad
PORT B: It is connected with LCD

8. E-blocks are small circuit boards each of which consists of a block of electronics that can be snapped
together to form an electronic system. There are two kinds of E-block
E-block
Upstream boards
Downstream boards

9. Used Components of E-Blocks
EB005 LCD board
EB014 Keypad RS232

10. Jumper Setting of E-Blocks
Board PORT Settings
Keypad D No settings
LCD B Jumpers on DEFAULT
Sensor A Jumpers on DEFAULT
RS232 C
C
Jumpers:
R& TX SELECTION
CTS & RTS SELECTION
1
Patch System wire links:
SPI/DAC C
Jumpers:
SDO, SDI & SCK SELECTION
A HIP EN SELECTION
1
Patch System wire links:
None
C

11. Setting up the GSM modem
It can operates between 6vdc to 40vdc
RS232 is used to connect the modem with E-Blocks.
Need a active SIM card with sufficient credit.
Need to connect an Antenna with it to get network connection.

12. Testing GSM Modem
Before using the GSM modem with E-Block system it needs to be test by
HyperTerminal using different AT Command
•AT+CREG?
•AT%CGREG?
•ATD
•ATH
Checking of GSM, GPRS Setting, Outgoing & Incoming Call

13. Compiling Procedure
Running the simulation

14. Project Software
To complete this project there are two software has been used. Their names are given below:
•Flowcode
•PPP
Steps of Flowcode

15. Clock setting of Microcontroller
•Crystal clock
•RC clock
Clock signal control the speed of operation.

16. Selection and Editing of Components

17. RS232 setting
RS232 is the communicator, which Tx and Rx data modem and PIC micro.

18. Call Macro icon properties
Call to another Macro. Macro means small programs which used many
time.

19. Call Component Macro

20. loop icon properties
Loop while:1 means loop forever.
Loop until: until the condition is true.
Loop count: How many time loop are running.

21. Decision properties

22. Calculation icon properties
Provide the logical function

23. String Manipulation
AT+CREG
AT%CGREG?
AT+CLIP=1,1 to see caller ID
ATD
ATA
ATH

24. Delay
Programmed is running too fast, So Add the delay function

25. Open the HEX file Send the program
:020000001C2DB5
:08000800FF00030EFC000A0ECC
:0C001000FD00040EFE008A110A12452DAE
:1000200000000000C10B10280800C308031D192898
:10003000080009300000FF3E031D1A2800000000E0
:10004000C30B1928080083160313DA010230DB0002
:100050001030DC006F30DD00E001DD08031908001E
:100060005C08DE00DF015B18DE17DB185F1483130A
:100070005F1883175E0884000008E100E11B742804

26. Developed Program
Program for calling system:
It has three state:
Idle
Ringing
Connected
When the modem detects an incoming call it transmits the message “RING” at regular
intervals (approximately 2 seconds).
Steps to Write Program:
LCD Initializing
Sending AT+CLIP
Checking incoming call
Taking Number from Keypad
Speed Dialing
Sending ATA
Sending ATH

27. Main Program for calling

28. Taking Number from Keypad

29. Speed dialing

30. Receiving a Call Call termination

31. Main Program’s Tx Macro Main Program’s Rx Macro

32. Program for sending sms
Steps to Write Program:
Taking Number from Keypad
The AT command required to configure
this option is Message Format
command:
AT+CMGF=1
The AT command to send a text
message is:
AT+CMGS=<”number”>
Writing message
<CTRL-Z> to finish sending

33. Sending Number Sending Message

34. Program for receiving sms
The AT command required to achieve this is the New Message Indication
command:
AT+CNMI=2,2

35. Simulation and Result
Software Output
Speed dialling (out going call):
Hardware Output

36. Speed dialling call termination
If we press ‘*’ Key it will terminate by sending ATH command

37. Taking and Dialing a Number from Keypad
If we press the ‘5’ key on keypad a option will be appeared showing “Enter No” on Software LCD .than we have
to enter a mobile number which will be saved in a variable named “K_Buffer”.
if we press the ‘#’ Key on keypad, the entered number will be dialled By a AT command that is
“ATD01710036458;”

38. Incoming Call
Hardware output
Now if we press the ‘#’ key on the keypad the incoming call will be received by sending a AT command to
modem as “ATA”
If we press ‘*’ Key it will terminate.

39. Sending of sms: When we will press the ‘#’ key a AT command that is “AT+CMGS=<”01717405762”>
” is sent to the modem
Software Output Hardware output

40. Receiving of sms
The figure is showing received message from a remote mobile phone

41. Conclusion
There are three existing program has been modified separately for
calling, sending and receiving sms which is necessary to developed a
general phone.
But it works slowly because of during the execution of large program the
device faces some delay as its fixed clock speed and also for limitation of
LCD display and KEYPAD

42. For Your Time