System design of cordless automatic answering telephone

This article refers to the address: http://

Abstract : This paper introduces the hardware structure and software program flow of a cordless automatic answering machine host system, and focuses on the working principle of automatic answering.
Keywords : CATD OGM ICM

I. Introduction

The Cordless Telephone Answering Device (CTAD-----Cordless Telephone Answering Device) is a cordless telephone, and its main unit is an automatic answering telephone. It can automatically turn on the incoming call and the player's main message. OGM (OutGoing Message), recording guest message ICM (InComing Message), and some can also record the content information of the two parties when making a call. These unique features make it an irreplaceable role for caller ID phones and voice mailboxes. At present, such telephone terminal products are widely used in developed regions such as Europe and the United States. Our HWL460(2)P/T is China's first cordless automatic answering machine that has been approved by the former Ministry of Posts and Telecommunications. This paper introduces the system design of its host---hardware structure and software flow. The system design of mobile phone is the same as that of ordinary cordless telephone.

Second, the main performance characteristics of the system

1, the machine owner OGM 20 seconds, using analog storage IC, can still be retained after power failure;
2, guest message ICM, 30 seconds each time, a total of 60 minutes, using micro-tape, can mark new and old information and decide whether the new information covers the old information;
3, can use the cordless mobile phone to monitor the ICM information being recorded and play the recorded ICM information;
4. The external telephone can remotely play ICM information by password;
5, in line with China's 45/48MHZ frequency standard and the national standard for answering telephones.

OGM uses analog storage IC recording and playback, and ICM uses micro-tape recording and playback. This recording media optimization combination effectively avoids poor performance of pure tape recording control, low movement reliability, troublesome retrieval information, etc. Disadvantages, but also avoid the disadvantages of pure digital recording inconvenient information transfer and carrying [1]. Another major feature of the system is that the cordless mobile phone can control the movement of the system movement and the content of the information. The concise system hardware structure design makes the system highly reliable and low cost. T2.gif (9085 bytes)

Third, the system's hardware structure and working principle

Â Â Â Figure 1 is the hardware structure block diagram of the host system, which is mainly composed of COP880C microcontroller controller, ISD1020AX analog storage IC, LA2806M answering telephone dedicated IC, KA2404 movement timing circuit, LM567 DTMF remote control code detection circuit and cordless telephone corresponding The hardware circuit is composed. Figure 2 shows the internal structure and pin function diagram of the LA2806M.

As can be seen from the structure diagram, COP880C (hereinafter referred to as COP8) is divided into five parts to control the relevant hardware circuits:

1. Function port F1: Output the corresponding combination level through F1 (Pin17~21) to control the internal 11 switches of LA2806M SWIC) to make the signal path of the corresponding function turn on.

2. Function port F2: Control the ISD1020AX (STIC) recording information and playback information by F2 (Pin 1, 2, 31, 39) according to the corresponding timing input/output control signals.

3. Function port F3: Control the movement of the movement in the playback/fast forward, recording, rewinding, etc. by F3 (Pin15, 23, 30, 35) according to the corresponding timing input/output control signals.

4. Function port F4: Control the high frequency receiving RF RX, high frequency transmitting RF TX, and compression expansion TK10659 circuit of the cordless telephone through F4 (Pin3, 25, 26, 27, 36, 38) to realize the connection with the cordless mobile phone. .

5, function port F5: through F5 (Pin24, 14, 5, 22) control related circuit to achieve contact with the external line: turn on / off the outside line, PULSE dial, DTMF remote password detection, ring detection and VOX voice control.

Pin38 in the structure diagram is a multi-function multiplexed pin - transmit data TXDATA, dual tone multi-frequency dial DTMF, prompt tone BEEP, in addition to RESET reset pin, CHG charging code and detection pin, LOW PWR low power Information protection detection pin.

The following describes the working principle of automatic answering in combination with the structural block diagram.

1. OGM recording: If the OGM REC/PLAY button is pressed, the Pin9 of COP8 is input low level. During this period, F1 of COP8 outputs LHLLL level to control SWIC to make it in OGM REC recording state, and port F2 also makes STIC at Record information status: During this period, the MIC voice signal â†’ SWIC Pin6 â†’ Pin8 â†’ STIC Pin20, the MIC information is input from the STIC Pin20 and recorded in its non-volatile analog memory array. The A0~A7 pins are all grounded, so that The chip recording mode is selected to record only once for 20 seconds.

2. OGM playback: Press the OGM REC/PLAY button, then COP8 Pin11 inputs a trigger pulse. After detecting its falling edge, F1 outputs LLHLH level to control SWIC, and F2 controls STIC according to the playback timing signal. Information stored in STIC â†’ Pin14 â†’ SWIC Pin11 â†’ Pin17 â†’ SP speaker.

3. OGM release: Press the ANSWER answer button to put the system in the ANSWER response state. If the outside line comes to the bell, the RING DET detection circuit detects that the RD pin of the COP8 is low. When the TXPWR pin goes low, the RFTX transmit circuit and the TXDATA output DATA to the RFTX MOD ring the handset; ICM new information NEW MESSAGE, after 12 seconds, FF8 F1 and F2 output LHHLH level and OGM playback timing signal respectively to let the system put OGM information, otherwise it takes 24 seconds to put OGM; meanwhile, COP8 Pin24 output low power The HOOK RL action is turned on to the outside line, and the signal flow issued by the OGM is STIC Pin14â†’SWIC Pin11â†’Pin22â†’324Aâ†’L-OUTâ†’outside line.

4. ICM recording: When the OGM releases the information to the end of the external line, the SOM EOM pin outputs a low-level 15.6ms pulse to the COP8 Pin2. After the COP8 is detected, its F1 output HLHHH level causes the SWIC to be in the ICM REC state. At the same time, the FF8 port F3 outputs the corresponding signal to make the movement DECK in the recording state. The flow direction of the ICM recording signal is: external lineâ†’L-INâ†’COP8 Pin5â†’Pin8â†’Pin10â†’Pin2â†’P/R HEAD recording head. During the ICM recording, if the external line hangs up or does not talk for 7 seconds, the Pin25 of the SWIC will output the VOX signal to the Pin22 of the COP8 to exit the ICM REC; if the ICM recording time exceeds 30 seconds, the ICM REC will also be exited.

5, ICM playback / fast forward, rewind (slightly)

6. External password remote control ICM: During the OGM release, if the external telephone dials the password (one digit) of the local machine with DTMF dialing, the DTMF signal flows through the decoding circuit composed of LM567. If the dialed password is correct, then Output a low level to Pin14 of COP8. After COP8 detection, make F1 separate LLHLL and port F3 also output corresponding timing signal to make the movement in the ICM state. The signal flow direction is:

P/R HEADâ†’SWIC Pin2â†’Pin8â†’Pin10 Pin21â†’Pin20â†’Pin17â†’SP Speaker Pin22â†’324Aâ†’L-OUTâ†’External Line

7. The cordless mobile phone monitors the ICM signal being recorded: When the ICM is recording, if the cordless handset presses the LISTEN monitor button, the RF RX circuit detects that the corresponding DATA is sent to the Pin36 of the COP8, and the COP8 recognizes correctly and its F4 will make the RF TX. When the circuit works, the TXMUT is not muted. At this time, the signal from the outside line is sent to the mobile phone through the following flow when sending the ICM recording: L-INâ†’324Bâ†’C.INâ†’C.OUTâ†’MODâ†’ANT.

8. The ICM information is played by the cordless mobile phone: In the standby state, the RF RX circuit receives the DATA signal of the cordless mobile phone according to its PLAY key, and inputs it to the Pin36 of the COP8. After the COP8 is recognized, the F1 and F3 will output corresponding control signals to make the system work at the ICM. The playback state, while the F4 control signal makes the RF TX circuit work and cancels the TX mute, the ICM signal of the movement P/R HEAD head is released to the SP speaker, and also according to the following channel to the mobile phone: SWIC Pin21â†’324Bâ†’C .INâ†’C.OUTâ†’MODâ†’ANT

Fourth , the system software design process

The control center of this system is a cost-effective COP880C microcontroller [2] with 8-bit memory mapping architecture, micro-bus + TM serial I/O port, 16-bit timer with capture registers and auto-reload registers /Counter and multi-level interrupt source----External interrupt, software interrupt, timer interrupt or capture interrupt. The software of the system adopts modular design, which mainly includes initialization module fast BS-INI, interrupt service module fast BS-INT, keyboard scanning processing module fast BS-KEY, receiving command module fast BS-RCV, transmitting command module fast BS-CMM, Dial-up processing mode fast BS-DIA and recording and playback mode fast BS-TAD. Figure 3 is a flow chart of the main program. The DTMF signal in this program is to use the CPU to output the PWM signal on one pin, and obtain the small distortion DTMF signal through the peripheral BPF bandpass filter. There is neither a hardware circuit for generating DTMF in the chip nor a DA conversion network for ordinary resistor row. It is a simple D/A converter constructed by using a timer-register bank in the automatic reload mode.

V. Conclusion

The system design integrates single-chip software technology, high-frequency communication technology, analog telephone communication technology and electromechanical integration. Mass production and use for many years prove that the system is reasonable in design and reliable in performance. The system design can be deepened in two aspects. One is functional, such as improving to 25 channels, increasing the sound of the environment in which the external monitoring host is located, and increasing the two-way recording function when the cordless mobile phone makes a call--using the ICM tape to record the speech of both parties. Content; second, performance, without tape recording, or storage IC soldered to the internal circuit board, but with an IC card that can extract and encrypt the recorded information.

Soccer Ball/Volleyball/Basketball

Basketball,Pu Basketball,Rubber Basketball

Tengbo Sports Co., Ltd. , http://www.shpooltables.com