joe1986
Full Member level 4
dtmf decoder proteus
hi friends, i am doing a project "WIRELESS TEXT MESSAGING USING MOBILE/LANDLINE PHONE"
SOFTWARE:
The msg.asm program is written in Assembly language and compiled using Metalink ASM51 cross-compiler.
HARDWARE:
1. There are 2 mobiles used one at the transmitting end and the other at the receiving end.
2. At the input a condenser microphone and an amplifier using IC LM 358 and DTMF DECODER 8870.
3. An LCD (16*2 DISPLAY) is used at the ouput along with a microcontroller (AT89S8252).
PROJECT DISRIPTION:
The message is transmitted by calling the second mobile phone and typing the desired message at the transmitter end. when the handset of the phone at the receiver end is picked up, you can type the message on the phone at the transmitting end. The receiver end comprises of input, decoder and display sections.
The input section consists of a mobile/landline phone, condenser mic and audio amplifier. For the decoder, the underlying concept is DTMF signal reception and decoding the signal to BCD format through DTMF decoder 8870. The display section consists of a microcontroller and the LCD. The microcontroller processes the decoded signal and outputs it for display on the LCD in the form of text message.
Once the connection is established between the two phones (as in normal case), whatever phone key is typed at the transmitting end, the corresponding DTMF tone is heard in the earpiece of the receiver (phone). The earpiece is connected to a microphone. The microphone (mic) picks up the DTMF tone. Its output is amplified by means of an op-amp and this output is fed to the DTMF decoder. The DTMF decoder would give the corresponding BCD value of the tone.
The LED’S acts as a visual indicator, when the valid signal is received by the system. The tone output is fed to an inverter buffer. The output of the inverter is fed to PORT 2 of the microcontroller. The microcontroller, connected to the LCD through PORT 0, reads PORT 2, processes the data and sends the output data through PORT 0 to the LCD and the message is displayed in the LCD. No separate driver is used for the LCD. It is driven directly by the microcontroller.
The microcontroller requires regulated 5V DC supply. Reset pin 9 of the controller is connected to 5V through reset switch S1. you can press reset switch two or three times for proper display of characters on the LCD.
This system can be used in noisy environments of factories as a means of communication among workers. The cursor will initially point to the first location in the LCD when power in the circuit is switched on. Conventionally you type a message on your mobile Phone as follows; To transmit character ‘a’ press button 2 on the mobile only once. For character ‘b’ press button 2 twice within a short time interval and for character ‘c’ press it thrice. For digit ‘2’ press button 2 four times. Each key pressed on the phone generates two tones of specific frequencies, so a voice or a random signal can’t imitate the tones. One tone is generated from a high-frequency group of tones and the other from a low-frequency group.
For example , to send message ‘efy3’, press button 3 followed by button 2 to display ‘e’, press button 3 twice to display ‘f’, press button 9 followed by button 3 to display ‘y’ and finally press button 3 followed by button 4 to display button ‘3’.
i have been using PROTEUS 7.1 to check whether the program gives the desired result (i tried interfacing the microcontroller and the LCD in proteus) and tried running the code to check the output but there was no success
can anyone tell me as to what is the problem in the program or what modifications can be made in the program to get the desired output
here is the file which contains the proteus file and my assembly language program
hi friends, i am doing a project "WIRELESS TEXT MESSAGING USING MOBILE/LANDLINE PHONE"
SOFTWARE:
The msg.asm program is written in Assembly language and compiled using Metalink ASM51 cross-compiler.
HARDWARE:
1. There are 2 mobiles used one at the transmitting end and the other at the receiving end.
2. At the input a condenser microphone and an amplifier using IC LM 358 and DTMF DECODER 8870.
3. An LCD (16*2 DISPLAY) is used at the ouput along with a microcontroller (AT89S8252).
PROJECT DISRIPTION:
The message is transmitted by calling the second mobile phone and typing the desired message at the transmitter end. when the handset of the phone at the receiver end is picked up, you can type the message on the phone at the transmitting end. The receiver end comprises of input, decoder and display sections.
The input section consists of a mobile/landline phone, condenser mic and audio amplifier. For the decoder, the underlying concept is DTMF signal reception and decoding the signal to BCD format through DTMF decoder 8870. The display section consists of a microcontroller and the LCD. The microcontroller processes the decoded signal and outputs it for display on the LCD in the form of text message.
Once the connection is established between the two phones (as in normal case), whatever phone key is typed at the transmitting end, the corresponding DTMF tone is heard in the earpiece of the receiver (phone). The earpiece is connected to a microphone. The microphone (mic) picks up the DTMF tone. Its output is amplified by means of an op-amp and this output is fed to the DTMF decoder. The DTMF decoder would give the corresponding BCD value of the tone.
The LED’S acts as a visual indicator, when the valid signal is received by the system. The tone output is fed to an inverter buffer. The output of the inverter is fed to PORT 2 of the microcontroller. The microcontroller, connected to the LCD through PORT 0, reads PORT 2, processes the data and sends the output data through PORT 0 to the LCD and the message is displayed in the LCD. No separate driver is used for the LCD. It is driven directly by the microcontroller.
The microcontroller requires regulated 5V DC supply. Reset pin 9 of the controller is connected to 5V through reset switch S1. you can press reset switch two or three times for proper display of characters on the LCD.
This system can be used in noisy environments of factories as a means of communication among workers. The cursor will initially point to the first location in the LCD when power in the circuit is switched on. Conventionally you type a message on your mobile Phone as follows; To transmit character ‘a’ press button 2 on the mobile only once. For character ‘b’ press button 2 twice within a short time interval and for character ‘c’ press it thrice. For digit ‘2’ press button 2 four times. Each key pressed on the phone generates two tones of specific frequencies, so a voice or a random signal can’t imitate the tones. One tone is generated from a high-frequency group of tones and the other from a low-frequency group.
For example , to send message ‘efy3’, press button 3 followed by button 2 to display ‘e’, press button 3 twice to display ‘f’, press button 9 followed by button 3 to display ‘y’ and finally press button 3 followed by button 4 to display button ‘3’.
i have been using PROTEUS 7.1 to check whether the program gives the desired result (i tried interfacing the microcontroller and the LCD in proteus) and tried running the code to check the output but there was no success
can anyone tell me as to what is the problem in the program or what modifications can be made in the program to get the desired output
here is the file which contains the proteus file and my assembly language program
