CN1652505A

CN1652505A - Control circuit of LT 8031 GPRS IP wireless digital transmission terminal for remote-digital transmission

Info

Publication number: CN1652505A
Application number: CN 200410023568
Authority: CN
Inventors: 林东
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-02-07
Filing date: 2004-02-07
Publication date: 2005-08-10

Abstract

The disclosed circuit is composed of main control circuit, ON-OFF control circuit, electrical level conversion circuit, channels switching circuit, input and output interface circuits, and watchdog of hardware circuit. Through ON-OFF control circuit, channels switching circuit, electrical level conversion circuit, and input and output interface circuits in sequence, the main control circuit is connected to hypogyny device electrically. Connected to ON-OFF control circuit and interface of MODEM communication port, the main control circuit controls connection to GPRS IP MODEM. Output of watchdog circuit is connected to input end of main control circuit. The invention makes LT8031 realize seamless coverage without need of fixing IP and host by using advanced GPRS technique. Advantages are: minimum flow charging, providing simpler network interface for users, flexible to select interfaces through jumper, and all sided optimization making development easier etc.

Description

The control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission

Technical field

The present invention relates to a kind of wireless data transfer module (control circuit of wireless data sending terminal) that is used for technical grade, be a kind of control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission concretely, can be used for the control that the exchanges data between the external equipments such as GPRS IP MODEM and ammeter is carried out.

Technical background

Since radio network technique began one's study and came into operation the eighties in 20th century, had flexibility, easy to use and exempt from advantages such as stringing and progressively grow up with it.Particularly network technology has obtained great breakthrough in recent years, has accelerated the development speed of radio network technique and product.Wherein global system for mobile communications (abbreviation gsm system) is a kind of circuit switching system that has been used widely, because the GSM message transmission rate is low, this circuit exchange mode carries out transfer of data can not make full use of Radio Resource, increased the network burden of GSM and can not satisfy the demand of market the packet data cellular telecommunication business, and can only use the note form to transmit data, can't accomplish " real-time online ", " chargeing according to quantity ".The GPRS that grew up in recent years (General Pack Radio Service is called for short GPRS) is a kind of new system that is used for packet data bearers and transport service that grows up on the gsm system basis.The most basic difference of GPRS and gsm system is, GSM is a kind of circuit switching system, and GPRS is a kind of packet switching system.GPRS is in the carrying of data service and support very remarkable advantages of tool, but more efficient use radio network information channel resource, be specially adapted to intermittently, aperiodic transfer of data, a spot of transfer of data, the larger capacity data are frequent transmission etc. not, and the technical advantage of GPRS also shows the following aspects: the transmission rate height; The resource utilization height: turn-on time is short: always online; Support IP agreement and agreement X.25; Have reasonable fee etc.But using the GPRS IP MODEM following defective that occurs now and then according to other producers on the market: 1, in unattended occasion, abnormal conditions appear in GPRS IP MODEM can't guarantee automatically reset reliability, make equipment be in " deadlock " state for a long time easily, influenced the normal operation of system.2, because the fixing IP resource-constrained of public network, the wireless telecommunication system that GPRS IP MODEM is formed, under the situation that administrative center goes offline, GPRS equipment is interrupted with the link that is connected of administrative center, want the attendant to the on-the-spot new IP address that produces according to administrative center, system is reset, caused the waste of human and material resources.3, when administrative center's receiving equipment power failure or " deadlock ", GPRS equipment can't judge that administrative center disconnects.Problems such as 4, baud rate can't change, communication interface is single.

Summary of the invention

The objective of the invention is to overcome above-mentioned deficiency, thereby design a kind of control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission, it can use dynamic IP, can also allow the user easier of the set wire jumper selection of this circuit distinct device interface, more practical and convenient.

The present invention realizes with following technical scheme: it mainly comprises governor circuit (1) (being circuit main control chip and peripheral components and parts), ON-OFF control circuit (2), level shifting circuit (3), channel commutation circuit (4), input/output interface circuit and hardware watchdog circuit compositions such as (5), wherein governor circuit (1) is successively by ON-OFF control circuit (2), channel commutation circuit (4), level shifting circuit (3) and input/output interface circuit are electrically connected in proper order with slave computer (as external equipments such as ammeters), governor circuit (1) also is connected with MODEM communication terminal interface with being connected between control GPRS IP MODEM and other equipment by ON-OFF control circuit, is used to wherein to guarantee that the output of the hardware watchdog circuit (5) of normal operation circuit is the input that is connected to governor circuit (1).When slave computer (as ammeter or other external equipments) needs under transparent mode to carry out exchanges data by MODEM and host computer, land instruction to MODEM by the host computer transmission, single-chip microcomputer (U6) in the governor circuit (1) carries out query manipulation to the note that MODEM receives, in case during the corresponding power-on command that inquires that host computer sends, will require MODEM to enter operating state, MODEM opens transparent mode when landing, when MODEM land finish after, just can carry out mutual exchanges data between it and the slave computer, at this moment, single-chip microcomputer will be monitored their communication, if MODEM receives the shutdown command that host computer transmits, single-chip microcomputer will cut out transparent mode once more, and cuts off the communication between them, makes it be returned to front message search state again.

The present invention is owing to used advanced GPRS technology, and adopt foregoing circuit to make LT8031 can realize seamless covering, need not fixedly IP, need not fixed host computer, realize minimum charge on traffic, and the practical problem that product applications ran into of can combining closely, for the user provides simpler network interface, can satisfy the needs of distinct device interface, the user can select flexibly by the equipment wire jumper, and comprehensively optimizes and upgrade, make product development become easier, faster.

Description of drawings

Fig. 1 is a circuit block diagram of the present invention.

Fig. 2 is a kind of circuit theory diagrams of the present invention.

Wherein: 1～governor circuit (circuit main control chip), 2～ON-OFF control circuit, 3～level shifting circuit, 4～channel commutation circuit, 5～hardware watchdog circuit, 6～MODEM communication terminal interface, 7～slave computer communication terminal interface.

Embodiment

Below in conjunction with accompanying drawing physical circuit of the present invention and operation principle are described in further detail.

Governor circuit described in the technology of the present invention solution (1) mainly is by single-chip microcomputer U6 (can adopt AT89C4051), crystal resonator E1 (adopting 11.0592M) and capacitor C 6, C7, C8 forms, wherein E1 and C7, C8 constitutes oscillating circuit, C6 is the filter capacitor between power supply and the ground, the RST end of single-chip microcomputer U6 is the input of hardware watchdog circuit (5) reset signal, the external reset pulse that provides single-chip microcomputer required is provided, the CON of U6 end is slave computer and GPRS IP MODEM communication/control end of switching is set, and the WDI of U6 holds and is connected with the hardware watchdog corresponding port.

Two, ON-OFF control circuit described in the technology of the present invention solution (2) has adopted two 4,066 6 analog switch U1A in the integrated package, UIB, UIC, U1D, U2A, U2B and two Schmidt triggers are formed three circuit-switched data passages, assigning instruction by single-chip microcomputer U6 allows 4066 to carry out the passage switching, first via data channel is by U1A, U2B control, be mainly used in the communication of the external equipments such as ammeter of single-chip microcomputer U6 and composition slave computer, secondary route U1C, U1D control, be after system enters transparent mode, host computer and slave computer carry out the passage of exchanges data, Third Road is by U2A, U2B control is used for single-chip microcomputer U6 and MODEM communication.

Three, totally three groups of wire jumper JP1, JP2 form (every group contains 2 wire jumpers) to the channel commutation circuit (4) described in the technology of the present invention solution by two parts.One group on every part left side RS485 wire jumper for being connected with integrated package U4 (being MAX1487), middle one group of RS232 wire jumper, the direct continuous TTL communication (being the TTL wire jumper) that is used for of another group of the right for being connected with integrated package U5 (being MAX232).

Four, the level shifting circuit described in the technology of the present invention solution (3) comprises the change-over circuit composition of TTL/RS232 and two parts of TTL/RS485, wherein the RS232 circuit is made up of U5 (being the MAX232 chip) and capacitor C 1, C2, C3, C4, C5, T1IN is the Transistor-Transistor Logic level input, T1OUT is the RS232 level output end after changing, and R1IN is that RS232 level input R1OUT is the Transistor-Transistor Logic level output after changing; RS485 circuit wherein is made up of U4 (being the MAX1487 chip) and a Schmidt trigger, the driving Enable Pin (DE) of chip and reception Enable Pin (1RE) are respectively applied for controlling and driving end (DI) and receiving terminal (RO), in transfer process, by DI and RO two ends input Transistor-Transistor Logic level, meet the level of RS485 standard then by A, the output of B two ends.

Five, the hardware watchdog circuit (5) described in the technology of the present invention solution is made up of integrated package U7 (being the MAX706 chip) and Schmidt trigger, capacitor C 9, resistance R 2, diode D1 and chip U3D, uses diode D1 to change the misoperation that causes WDO for the level that prevents MR.

Six, input/output interface circuit of the present invention comprises that the data wire socket JP4, chip U3B, the U3C that are connected with MODEM communication terminal interface (6) constitute, and comprises that also the data wire socket JP3, the resistance R 1 that are connected with slave computer communication terminal interface (7) constitute.

In circuit of the present invention, the WDI of single-chip microcomputer U6 holds in the course of the work, if do not receive the triggering signal from MCU in 1.6S, and WDI is in non-high-impedance state, then WDO output step-down.As long as reset signal is effective or WDI input high resistant, then the WatchDog Timer function just is under an embargo, and keeps zero clearing and not-time state.The generation of reset signal can be forbidden timer, in case can reset signal cancel and the WDI input detects low level or the high level saltus step that is as short as 50ns, timer will begin the timing of 1.6s.The saltus step meeting zero clearing timer that is the WDI end also starts once new time-count cycle.

In circuit, the effective hand-reset input of low level (MR) can be moved to high level by the pull-up current source of 250mA in the single-chip microcomputer, and can be pulled into low level by the push-button switch of external CMOS/TTL logical circuit or an end ground connection.Do not need to adopt outside debouncing circuit, reason is minimum for being enough to eliminate the shake of mechanical switch the resetting time of 140ms.Simply the MR end is connected to the WDO end, just can makes the overtime generation reset pulse of WatchDog Timer.

Interface with GPRS IP MODEM in the input/output interface circuit is one or six pin sockets, and the interface that links to each other with slave computer is one or four pin sockets and resistance R 1.R1 is the pull-up resistor of output control pin.U3B and U3C are used for the shaping of output waveform.Six pin of socket of linking to each other with MODEM be successively VCC, GND, RXD, TXD, RST ,/IGT.Four pin of socket of linking to each other with slave computer are CON, B (or TXD), A (or RXD), GND successively.A, B are the RS485 interface, and RXD, TXD, GND are the RS232 interface, and TXD, RXD are the TTL interface.

Circuit control procedure of the present invention is as follows: the LT8031 in the governor circuit powers on after the operation, and single-chip microcomputer at first assigns instruction and cuts out that already present transparent mode is connected between host computer and the slave computer, enters short message mode then and carries out message search.In this process, the note that LT8031 sends here host computer will be carried out the order extraction, with the validity that guarantees that slave computer receives orders.After LT8031 received that requirement that host computer is sent here enters the transparent mode order, 4051 will control analog switch set up transparent mode between host computer and the slave computer.At this moment, host computer and slave computer just can carry out required exchanges data.In the exchange, if LT8031 does not receive any instruction of host computer in 5 minutes, then system judges that the communication between two machines finishes, and the transparent mode that single-chip microcomputer will cut out between two machines once more connects, then enters the order of short message mode inquiry host computer.More than be the complete work period of LT8031.

Claims

1, a kind of control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission, it is characterized in that it comprises governor circuit (1), ON-OFF control circuit (2), level shifting circuit (3), channel commutation circuit (4), input/output interface circuit and hardware watchdog circuit (5) are formed, wherein governor circuit (1) is successively by ON-OFF control circuit (2), channel commutation circuit (4), level shifting circuit (3) and input/output interface circuit (6) are electrically connected in proper order with slave computer, governor circuit (1) also is connected with MODEM communication terminal interface (6) with being connected between control GPRS IP MODEM and other equipment by ON-OFF control circuit (2), be used to wherein to guarantee that the output of the hardware watchdog circuit (5) of normal operation circuit is connected to the input of governor circuit (1), when slave computer needs under transparent mode to carry out exchanges data by MODEM and host computer, land instruction to MODEM by the host computer transmission, single-chip microcomputer U6 in the governor circuit (1) carries out query manipulation to the note that MODEM receives, in case during the corresponding power-on command that inquires that host computer sends, will require MODEM to enter operating state, MODEM opens transparent mode when landing, when MODEM land finish after, just can carry out mutual exchanges data between it and the slave computer, at this moment, single-chip microcomputer will be monitored their communication, if MODEM receives the shutdown command that host computer transmits, single-chip microcomputer will cut out transparent mode once more, and cut off communication between them, make it be returned to front message search state again.

2, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1, it is characterized in that described governor circuit (1) mainly is by single-chip microcomputer U6, crystal resonator E1 and capacitor C 6, C7, C8 forms, wherein E1 and C7, C8 constitutes oscillating circuit, C6 is the filter capacitor between power supply and the ground, the RST end of single-chip microcomputer U6 is the input of hardware watchdog circuit (5) reset signal, the external reset pulse that provides single-chip microcomputer required is provided, the CON of U6 end is slave computer and GPRS IP MODEM communication/control end of switching is set, and the WDI of U6 holds and is connected with the hardware watchdog corresponding port.

3, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1, it is characterized in that described ON-OFF control circuit (2) is to adopt two 4,066 6 analog switch U1A in the integrated package, UIB, UIC, U1D, U2A, U2B and two Schmidt triggers are formed three circuit-switched data passages, assigning instruction by single-chip microcomputer U6 allows 4066 to carry out the passage switching, first via data channel is by U1A, U2B control, be mainly used in the communication of the external equipments such as ammeter of single-chip microcomputer U6 and composition slave computer, secondary route UIC, U1D control, be after system enters transparent mode, host computer and slave computer carry out the passage of exchanges data, Third Road is by U2A, U2B control is used for single-chip microcomputer U6 and MODEM communication.

4, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1, it is characterized in that totally three groups of wire jumper JP1, JP2 form (every group contains 2 wire jumpers) to described channel commutation circuit (4) by two parts, one group on every part left side is for being the RS485 wire jumper that MAX1487 is connected with integrated package U4, middle one group be the RS232 wire jumper that is connected with integrated package U5, the direct continuous TTL communication (being the TTL wire jumper) that is used for of another group of the right.

5, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1, it is characterized in that described level shifting circuit (3) comprises the change-over circuit composition of TTL/RS232 and two parts of TTL/RS485, wherein the RS232 circuit is that MAX232 chip and capacitor C 1, C2, C3, C4, C5 form by U5, T1IN is the Transistor-Transistor Logic level input, and T1OUT is the RS232 level output end after changing; R1IN is a RS232 level input, R1OUT is the Transistor-Transistor Logic level output after changing, RS485 circuit wherein is that MAX1487 chip and a Schmidt trigger are formed by U4, the driving Enable Pin (DE) of chip and reception Enable Pin (1RE) are respectively applied for controlling and driving end (DI) and receiving terminal (RO), in transfer process, by DI and RO two ends input Transistor-Transistor Logic level, meet the level of RS485 standard then by A, the output of B two ends.

6, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1 is characterized in that described hardware watchdog circuit (5) is that MAX706 chip and Schmidt trigger, capacitor C 9, resistance R 2, diode D1 and chip U3D form by integrated package U7.

7, the control circuit that is used for the LT8031 GPRS IP wireless data sending terminal of remote data transmission according to claim 1, it is characterized in that described input/output interface circuit comprises that the data wire socket JP4, chip U3B, the U3C that are connected with MODEM communication terminal interface (6) constitute, comprise that also the data wire socket JP3, the resistance R 1 that are connected with slave computer communication terminal interface (7) constitute.