CN103853684A

CN103853684A - Serial bus communication bridging device

Info

Publication number: CN103853684A
Application number: CN201410101079.7A
Authority: CN
Inventors: 乔东海; 张寒
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2014-03-18
Filing date: 2014-03-18
Publication date: 2014-06-11

Abstract

The invention discloses a serial bus communication bridging device. The serial bus communication bridging device comprises a main control module, four serial communication interface circuits which are connected with the main control module, a clock circuit, a power supply module, a baud rate setting module and a flow control switch, wherein the four serial communication interface circuits are respectively a first RS232 serial interface circuit, a second RS232 serial interface circuit, a USB (universal serial bus) serial interface circuit and a TTL/COMS (transistor-transistor logic/complementary metal oxide semiconductor) serial interface circuit, the first serial interface circuit is provided with a conversion circuit, four data cache areas corresponding to the serial interface communication interface circuits are arranged in the main control module, and the input end of the power supply module is connected to the USB interface. By adopting the serial bus communication bridging device, the conversion of multiple serial data can be realized, and the level and the baud rate can be matched.

Description

A kind of serial bus communication bridge

Technical field

The present invention relates to a kind of data transmission utility appliance, be specifically related to a kind of serial bus communication bridge, realize the communication function of the equipment room of different communication electrical standard, different baud rates.

Background technology

Along with the development of information and computer technology, increasing electronic equipment uses digital form to carry out information interaction communication.Especially in field tests, data upload to the computing machine that circuit Systemon-board need to be gathered completes and shows and storage.Modern computer is all furnished with RS232 and USB serial line interface, and this provides convenience for data transmission.But the serial data signal that circuit chip on board produces mostly is TTL or CMOS electrical standard signal, cannot mate with the signal of RS232 and USB electrical standard, this has brought trouble for data communication.At this moment just need in the time of hardware design, add corresponding level shifting circuit, and in actual applications, most applications only relates to the conversion between TTL, CMOS, these three kinds of electrical standards of RS232, if design all increases similar bus driving circuits each time, this has not only increased manufacturing cost, also for designer has brought unnecessary trouble, and the hidden danger that exists chip failure to produce.

On the other hand, USB is the standard configuration of current computing machine, but the equipment such as current opertaing device, instrument and meter and the remote terminal that still has many use RS232 serial line interfaces are applied in numerous areas, are transform immediately as USB mode and obviously have cost, enforcement and time-related problem.

Summary of the invention

Goal of the invention of the present invention be to provide a kind of reusable, can matched level, coupling baud rate, there is the serial bus communication bridge of flow control technology.

To achieve the above object of the invention, the technical solution used in the present invention is: a kind of serial bus communication bridge, comprise main control module, four serial communication interface circuits that are connected with main control module, clock circuit, power module, Configuration of baud rate module and flow control switch, described four serial communication interface circuits are respectively a RS232 serial port circuit, the 2nd RS232 serial port circuit, USB serial port circuit and TTL/COMS serial port circuit, described in each, serial port circuit is provided with change-over circuit, in described main control module, establish four data buffers corresponding with described serial communication interface circuit, the input end of described power module is connected to USB interface.

In technique scheme, two groups of Configuration of baud rate switches that described Configuration of baud rate module comprises that a corresponding RS232 serial port circuit and the 2nd RS232 serial port circuit arrange and display module.

Preferred technical scheme, described Configuration of baud rate switch is three toggle switchs.

Preferred technical scheme, described display module is seven-segment numeric indicator.

In technique scheme, described power module comprises rechargeable battery and power supply modulate circuit.

It is as follows that the present invention realizes the principle of work of communicating by letter between each serial ports:

1. a RS232 serial port circuit and the 2nd RS232 serial port circuit are realized the communication between two RS232 serial equipments of different baud rates:

Respectively two RS232 communication serial port equipment connections are arrived to a RS232 serial ports of the present invention and the 2nd RS232 serial ports, the one RS232 serial ports and the 2nd RS232 serial ports are set to different baud rates according to two RS232 serial equipments respectively by corresponding Configuration of baud rate switch, governor circuit read switch state is also first, second RS232 serial port circuit configuration baud rate automatically, and shows on corresponding display.Under the cooperation of governor circuit control and corresponding data buffer zone, the data that sent with the first baud rate through a RS232 serial ports by first serial equipment, send to second serial equipment by the 2nd RS232 serial ports with the second baud rate after treatment, and vice versa.The one RS232 serial ports and the 2nd RS232 serial ports are the in the situation that of normal use, and the serial ports baud rate of setting all should equate, in the time of data one-way transmission, can allow to send baud rate and be less than reception baud rate.When two serial ports are transmitted in both directions and baud rate while not mating, as required, transmitting terminal or receiving end need to support Flow Control and open Flow Control function, and this equipment also should be opened Flow Control at corresponding serial ports.

2.TTL/CMOS level asynchronous serial signal RS 232 electrical standard signal:

TTL/CMOS circuit is connected with bridge of the present invention by TTL/CMOS interface of the present invention.First the signal of TTL/CMOS circuit carries out buffer memory via data buffer, under the control of governor circuit, sends to RS232 serial equipment through the data cached of level conversion with the baud rate setting by RS232 serial ports.

Above-mentioned TTL/CMOS interface can comprise two kinds of connected modes that architectural characteristic is different, as SMA and row's pin, can adapt to so various application mode.

3.RS232 electrical standard signal turns USB electrical standard signal:

In the time that bridge of the present invention is connected on usb bus, COMPUTER DETECTION is carried out initial configuration and is started relevant driver equipment after the connection of equipment; Driver sends configuration order so that the Data Transmission Feature of RS232 interface to be set to equipment; Finally, in the time of data transmission, the driver on computing machine first by data packet transmission to USB interface, USB interface is read actual valid data and is kept in data buffer, then sends the data to by data buffer the equipment being connected with RS232 interface.

The conversion of 4.TTL/CMOS level asynchronous serial signal and USB electrical standard signal:

First TTL/CMOS level asynchronous serial data enters corresponding data buffer through TTL/COMS serial port circuit, under the control of governor circuit, more finally sends to USB interface equipment by USB interface through change-over circuit.Equally, in the time that TTL/CMOS electric level interface equipment need to receive the data from USB interface equipment, data enter the data buffer corresponding with USB serial port circuit by governor circuit control after level conversion, through the data after processing, send to receiving equipment by the data buffer corresponding with TTL/COMS serial port circuit.

Because technique scheme is used, the present invention compared with prior art has following advantages:

1. four serial communication interface circuits that bridge of the present invention arranges, can realize the conversion of multiple serial data, wherein, RS232 serial port circuit correspondence is provided with Configuration of baud rate switch and display, can realize the communication between two RS232 serial equipments of different baud rates.

2. the present invention is also provided with level shifting circuit, can realize the conversion between each level signal.

Accompanying drawing explanation

Fig. 1 is the structural representation of communication bridge of the present invention in embodiment mono-.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described:

Embodiment mono-: shown in Figure 1, a kind of serial bus communication bridge, comprise main control module, four serial communication interface circuits that are connected with main control module, clock circuit, power module, Configuration of baud rate module and flow control switch, described four serial communication interface circuits are respectively a RS232 serial port circuit, the 2nd RS232 serial port circuit, USB serial port circuit and TTL/COMS serial port circuit, described in each, serial port circuit is provided with change-over circuit, in described main control module, establish four data buffers corresponding with described serial communication interface circuit, the input end of described power module is connected to USB interface.

In the present embodiment, two groups of Configuration of baud rate switches that described Configuration of baud rate module comprises that a corresponding RS232 serial port circuit and the 2nd RS232 serial port circuit arrange and display module, described two groups of Configuration of baud rate switches are three toggle switchs, be respectively A2, A1, A0 and B2, B1, B0, its Configuration of baud rate is as shown in table 1:

The Configuration of baud rate table of first, second RS232 serial ports of table 1

The present invention adopts existing integrated circuit to realize, and wherein governor circuit is the fpga chip that embeds NIOS core.Described fpga chip adopts this chip of EP4CE22F17C6 of the cyclone of altera corp.This is a kind of FPGA of low price intermediate density, adopt the full copper SRAM technique of 0.060 μ m, logical block capacity is 22320, memory span is the about 74KBytes of 594Kbit(), phaselocked loop for clock control is provided, also have a special Double Date Rate (DDR) interface to be used for meeting DDR SDARM and FCRAM(fast cycle RAM) needs of storer, also support ASIC(Application-specific Integrated Circuit) device, core power voltage 1.2V, PLL supply voltage 2.5V, I/O supply voltage 3.3V.Under the control of governor circuit, the work that other module is orderly.

Buffer area 1,2,3,4 in figure is realized by FPGA internal RAM, large I setting, and general cache district 2 is larger, and other three are equally big or small, and support DMA function; Level translator uses the SN74ALVC164245 two-way level converting device of TI company, realizes the coupling between 3.3V and 5V signal; In TTL interface circuit, receiving circuit selects input end to have the SN74LS14 of Si Mite characteristic, and input port connects 20 kilohms of pull-up resistors, and output driving circuit is selected SN74LS244, connects 5V power supply; In CMOS interface circuit, receiving circuit selects input end to have the SN74HC14 of Si Mite characteristic, and input port connects 20 kilohms of pull-up resistors, and output driving circuit is selected SN74HC244, connects 3.3V power supply; Clock circuit adopts the 50MHz crystal oscillator of 3.3V Power supply, can select the brilliant space in Beijing to make the science and technology prosperous XO08-NACTC50MHz product DS1302 that company limited produces; The 5V power supply that power circuit input provides from USB interface, selects common voltage regulator (LDO chip) to produce 3.3V, 2.5V, 1.2V voltage, provides whole circuit to use; TTL-USB conversion chip can adopt the MAX13481 chip of MAXIM company; this chip is the USB compatible transceiver of have ± 15kV esd protection; can be connected with the low-voltage ASIC of USB device, when full speed operation (12Mbps), the complete compatible USB2.0 of transceiver; RS232 bus transceiver adopts the ADM3202 of Analog Devices company, and it is high speed, binary channels RS232/V.28 interface device, adopts+3.3 V single power supplies; USB hole seat is selected rectangle D-USB printed board connector, and RS232 serial communication needle stand is selected rectangle DB9 printed board connector, double contact pin 10 pins and 3 SMA connectors.Baud rate toggle switch, nixie display can be selected in market general toggle switch, nixie display.

Claims

1. a serial bus communication bridge, it is characterized in that: comprise main control module, four serial communication interface circuits that are connected with main control module, clock circuit, power module, Configuration of baud rate module and flow control switch, described four serial communication interface circuits are respectively a RS232 serial port circuit, the 2nd RS232 serial port circuit, USB serial port circuit and TTL/COMS serial port circuit, described in each, serial port circuit is provided with change-over circuit, in described main control module, establish four data buffers corresponding with described serial communication interface circuit, the input end of described power module is connected to USB interface.

2. a kind of serial bus communication bridge according to claim 1, is characterized in that: two groups of Configuration of baud rate switches that described Configuration of baud rate module comprises that a corresponding RS232 serial port circuit and the 2nd RS232 serial port circuit arrange and display module.

3. a kind of serial bus communication bridge according to claim 2, is characterized in that: described Configuration of baud rate switch is three toggle switchs.

4. a kind of serial bus communication bridge according to claim 2, is characterized in that: described display module is seven-segment numeric indicator.

5. a kind of serial bus communication bridge according to claim 1, is characterized in that: described power module comprises rechargeable battery and power supply modulate circuit.