This text provides a kind of design which fixes the telephone with terminal message taking 80C31 as top management CPU, have explained the operation principle of fixed telephone message terminal design method and each part from two respects of software and hardware of system. As to the difficult point met in development, such as CAS sound was measured, such problems as FSK information processing and LCD Chinese character character revealed have been explained especially.

Keyword: Message; Telephone; DTMF; FSK

Now, short information service popularizes day by day. Each telephone producer competitively designs and develops the terminal telephone of the message. In order to cooperate with the terminal specialized integrated chip of message that I develop, we design developing the fixed telephone that can send and accept the message. This telephone can also receive FSK form message spread under information center besides having incoming telegrams to reveal the function, can utilize DTMF and FSK two kinds of forms to upload information. There is better man-machine interface, can adopt editor’s message content of input method of the spelling. Can store 200 telephones, 200 messages downloaded, realize the looking for of the telephone number, download the reading of the message, such functions as the clock reveals. Introduce the systematic design from the hardware respect first below.

Part of the hardware

Systematic hardware principle block diagram of Fig. 1

Fig. 2 CAS measures the circuit of principle

The systematic hardware principle block diagram is shown in Fig. 1, now explain the function of every part.

CPU controls the part

Adopt 80C31 in the system as top management CPU, is responsible for the procedure procedure of the whole system, has expanded 32K RAM outside, 64K EPROM, is regarded as the telephone the memories of thin, message and the second word storehouse type matrix with AT29C040A of a block of ATMEL Companies.

CAS measures the circuit

CAS measures the circuit of principle. In the message telephone, the detection of CAS signal is essential, but ordinary telephone and incoming telegram in the past revealed the telephone did not have this function, chip that CAS sound measures the function is relatively rare too on the market, so, we have designed a kind of CAS sound to measure the circuit, in practical application, the result is good see Fig. 3 .

CAS is DTMF signal, the frequency is 2130/2750Hz, so adopt two single wave filters, if is CAS, then A, B clicks and exports as the high level, it is cut off that CAS emerges. SIGNAL is DTMF signal in the picture, CAS_CON measures the control circuit for CAS sound, acts as CAS_CON =At 1 o’clock, measure CAS sound; CAS_CON =At 0 o’clock, do not measure CAS sound. Act as and measure it to CAS, CASINT exports the high level.

EPLD integrated control circuit

External the intersection of control circuit and part adopt the intersection of ALTERA and EPM7128QC160 of Company, until 74 not used series and 4000 serial chips all integrate inside in the design, and it has 160 PINs, can meet the input and output signal in the system to the demand in charge of the foot. Have narrowed PCB area greatly, very convenient in the debugging, and improved the dependability of the whole system.

Because other parts have a ready-made chip or ripe circuit, here no longer explains.

Fig. 3 CAS measures the real circuit


Fig. 4 LCD reveals the flow diagram of the module

Part of the software

The software adopts the module to design, every module can be designed and debugged alone. Mainly there is a keyboard that deals with the module, system state and changes the module, telephone and deals with the module the treatment and sending including FSK message , LCD reveal module, stop, punish module CAS, FSK, shake bell, detection and the intersection of FSK and message to pluck on-hook receive . Besides stopping dealing with the module, other four pieces of module are circulated in the main program and transferred.

The keyboard deals with the module

Telephone and CPU work with the same button, is passed the transmission direction which imitates the on-off control button by CPU. While phoning the plucking machine normally, key value is transmitted to the dialing chip in the telephone; Transmit to CPU and deal with at the on-hook. Whether the monitoring that CPU does not stop has keys that is pushed, when it is pushed that there are keys, setting up the systematic state and changing marks as 1, otherwise 0. For being easy to use, increase ordinary telephone 4 buttons: Cancel the key key_C ,Main menu key key_M ,Choose the key key_OK ,The input method switches over the key key_CH .

The systematic state changes the module

This core that is the whole system controls the part. It carries on the treatment of key value in switch and state among the state according to the button and different states which the system lives in. As the systematic state is changed marks it as 1 o’clock, enter this module. Based on different key values, carry on corresponding treatment. The state that the system mainly presumes is as follows, initial state S_init ,Main menu state S_mainmenu ,Thin state S_menu1 of the telephone ,Message state S_menu2 ,The system sets up the state S_menu3 ,Add the state of the telephone number S_addphone_1 ,Add the name state of the telephone S_addphone_2 ,Add the telephone and store the position state S_addphone_3 ,Look for the telephone state S_lookphone ,Editor’s state S_edit_sm of the message ,Send the message state S_send_sm ,Read the message state S_read_sm When.

LCD reveals the module

This part is to reveal according to the state that the system is lived in. Mainly have display of the menu, the display of Chinese characters and the character, the display of the message downloaded edited, reveal that there are message and incoming telegram that reveal some such as the telephone number. While revealing, it is that Chinese characters of the message reveal together with ASCII yard that it is dealt with that the most difficult, because Chinese characters are the whole angle display, ASCII yard is the half-angle display, otherwise reveal the result is not good, and will involve looking through the initial position revealed in the page. Procedure procedure adopted in development.

Deal with the module in telephone

In this part, run with the message telephone, the incoming telegram reveals the telephone, and ordinary telephone. While coming as shaking the bell, enter the processing procedure of the telephone. Accept that exchanges FSK signal that the centre sent, and according to the content of the signal, determines it is a message, reveal the telephone. As to the message, send and reply information, change over to the module of short information processing; It is that an incoming telegram reveals CALLER ID to act as The telephone, will reveal the telephone number on LCD. If has not received FSK message, judge for the ordinary telephone. system does not consider temporarily the incoming telegram reveals the down DTMF form in the telephone . Fig. 5 is its flow diagram of procedure.

Cut off the processing procedure CAS, FSK, shake the bell, pluck the on-hook

In cutting off the processing procedure, mainly deal with the receiving of FSK signal, CAS signal, shake bell and pluck on-hook, measure, enable corresponding position 1 of sign, so that the main program is dealt with. Among them, the synchronous FSK information of adopting the way of inquiring first of acceptance of FSK signal, utilize one bunch of mouths of 51 one-chip computers to receive after the synchronism.

Fig. 5 telephone deals with the operation chart

Conclusion

Fixed telephone network that design message terminal to have ability to upload news and receive the intersection of short message and terminal down ability C type terminal station of news at the same time ,Satisfied ” technical specification based on that the fixed network short message conveys ” Requirement. Have offered for terminal specialized integrated chip of message and verified the platform.