CN104462000A - Nonpolar RS-485 interface chip with internal pull-up and pull-down resistors - Google Patents
Nonpolar RS-485 interface chip with internal pull-up and pull-down resistors Download PDFInfo
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- CN104462000A CN104462000A CN201410763434.7A CN201410763434A CN104462000A CN 104462000 A CN104462000 A CN 104462000A CN 201410763434 A CN201410763434 A CN 201410763434A CN 104462000 A CN104462000 A CN 104462000A
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- resistor
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/40—Bus structure
- G06F13/4063—Device-to-bus coupling
- G06F13/4068—Electrical coupling
- G06F13/4072—Drivers or receivers
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/40—Bus structure
- G06F13/4063—Device-to-bus coupling
- G06F13/4068—Electrical coupling
- G06F13/4086—Bus impedance matching, e.g. termination
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Logic Circuits (AREA)
- Semiconductor Integrated Circuits (AREA)
Abstract
The invention discloses a nonpolar RS-485 interface chip with internal pull-up and pull-down resistors. The nonpolar RS-485 interface chip comprises a chip frame and a driver, a receiver and a polarity adaptive module located in the chip frame; the chip frame further comprises a power pin and a ground pin; the nonpolar RS-485 interface chip further comprises one pull-up resistor and one pull-up resistor, one end of the pull-up resistor is connected with the equidirectional output end of the driver while the other end is connected with the power pin, one end of the pull-down resistor is connected with the inverted output of the driver, and the other end of the pull-down resistor is connected with ground pin. When the nonpolar RS-485 interface chip is connected with a bus, whether a first output port and a second output port are correctly connected with the corresponding buses needs not to be checked, and use is facilitated; the pull-up and pull-down resistors are added, so that mismatching is avoided during hybrid networking with existing bus networks.
Description
Technical field
The invention belongs to RS-485 communication interface chip field, a kind of chip internal is with the nonpolarity RS-485 interface chip of pull-up resistor, pull down resistor specifically.
Background technology
RS-485 is that the balancing twisted-pair line that utilizes that U.S. electric industrial combination meeting (EIA) is formulated makes the multi-point standard of transmission line, mainly for remote, high sensitivity, multi-point communication.
The interface chip of the existing RS-485 of meeting communication standard is divided into polarity and nonpolarity two kinds.Have polarity RS-485 interface chip structure as shown in Figure 1, it comprises an a driver D and receiver R.RS-485 interface chip wants practical function, must ensure when inputting a Transistor-Transistor Logic level from driver input end mouth DI, a differential voltage signal is exported from output port A and output port B after driver D process, the phase place of output port A is identical with driver input end mouth DI, and the phase place of output port B is contrary with driver input end mouth DI.Because have the output port A of polarity RS-485 interface chip and the port polarity of output port B to determine, therefore when networking application, require that output port A and output port B corresponding to being connected, otherwise can not will communicate with bus A and bus B respectively.Meanwhile, because the polarity of output port A and output port B is determined, can an external pull-up resistor be to power pins VCC on output port A when networking application, on output port B, an external pull down resistor is to grounding pin GND.
An other class is nonpolarity RS-485 interface chip, and as shown in Figure 2, it comprises an a driver D and receiver R to its structure, adds a polarity adaptation module in addition.Its realize function and have polarity RS-485 chip to be identical, but its advantage be can connect networking time need not consider that the output port A of chip will correspondingly with bus A and bus B respectively be connected with output port B, reduce connection networking time requirement; Even if there is the situation of reversal connection (the output port A of chip connects bus B, and output port B meets bus A) when connecting, the polarity adaptation module of chip internal can detect polarity automatically, and corrects connection error.But the weak point of existing nonpolarity RS-485 interface chip is, due to output port A and the uncertain mode that with bus be connected prior with output port B, therefore to add the upper pull down resistor of outside when networking.Like this, just cause when some is applied by the advantage brought of pull down resistor be not just present in, if more seriously non-polar being applied in there will be unmatched phenomenon with during old bus network (having polarity RS-485 interface) mixed networking, cause communication failure.
Summary of the invention
In order to overcome the above problems, the invention provides a kind of nonpolarity RS-485 interface chip with inner upper pull down resistor.
Technical scheme of the present invention is as follows:
With a nonpolarity RS-485 interface chip for inner upper pull down resistor, comprise chi frame and the driver, receiver, the polarity adaptation module that are arranged in chi frame; Described chi frame also comprises power pins, grounding pin, the first output port and the second output port; Described polarity adaptation module comprises the first switch, second switch, the 3rd switch and the 4th switch; The output terminal in the same way of described driver connects the input end in the same way of receiver, and the inverse output terminal of driver connects the reverse input end of receiver; Described first switch one end connects the output terminal in the same way of driver, and the other end connects the second output port; Described second switch one end connects the output terminal in the same way of driver, and the other end connects the first output port; Described 3rd switch one end connects the inverse output terminal of driver, and the other end connects the second output port; Described 4th switch one end connects the inverse output terminal of driver, and the other end connects the first output port; Also comprise pull-up resistor and pull down resistor, described pull-up resistor one end connects the output terminal in the same way of driver, and the other end connects power pins, and described pull down resistor one end connects the inverse output terminal of driver, and the other end connects grounding pin.
Advantageous Effects of the present invention is:
The present invention, relative to two kinds of RS-485 interface chips in prior art, combines the advantage of the two, and overcomes the shortcoming of the two.First, the present invention as RS-485 interface chip nonpolarity in prior art, when connecting bus, can need not check the first output port and be connected with whether its corresponding the second output port bus A be corresponding with bus B, easy to use.Secondly, owing to adding built-in pull-up resistor and pull down resistor in chi frame inside, through the adjustment of polarity adaptation module, no matter how polarity switch combines, the result finally obtained is all the output port pull-up that same bus A is connected by pull-up resistor, pull down resistor is by drop-down for the output port that same bus B is connected simultaneously, so just the external pull-up resistor of polarity RS-485 interface chip and pull down resistor is had to achieve same connected mode with of the prior art, and such setting, even if also there will not be unmatched phenomenon by when the present invention and old bus network (having polarity RS-485 interface) mixed networking, cause communication failure.
Accompanying drawing explanation
Fig. 1 has polarity RS-485 interface chip functional block diagram in prior art.
Fig. 2 is nonpolarity RS-485 interface chip functional block diagram in prior art.
Fig. 3 is the present invention's nonpolarity RS-485 interface chip functional block diagram.
In Fig. 1, Fig. 2, Fig. 3: R, receiver; D, driver.
Embodiment
The object of the invention is for nonpolarity RS-485 interface chip of the prior art can not additional pull-up, pull down resistor and cause apply on this shortcoming of some problems, in conjunction with the technical characterstic having polarity RS-485 interface chip of the prior art, provide a kind of solution pull-up resistor and pull down resistor being made in chip internal.
As shown in Figure 3, the present invention includes chi frame and the driver D, receiver R, the polarity adaptation module that are arranged in chi frame, the pin of chi frame comprises: driver input end mouth DI, receiver output port RO, power pins VCC, grounding pin GND, output port A and output port B.Polarity adaptation module comprises switch S 1, switch S 2, switch S 3 and switch S 4.Driver input end mouth DI connects the input end of driver D, and the output terminal in the same way of driver D connects the input end in the same way of receiver R, and the inverse output terminal of driver D connects the reverse input end of receiver R, and the output terminal of receiver R connects receiver output port RO.In polarity adaptation module, switch S 1 one end connects the output terminal in the same way of driver D, and the other end connects output port B; Switch S 2 one end connects the output terminal in the same way of driver D, and the other end connects output port A; Switch S 3 one end connects the inverse output terminal of driver D, and the other end connects output port B; Switch S 4 one end connects the inverse output terminal of driver D, and the other end connects output port A.Pull-up resistor R1 one end connects the output terminal in the same way of driver D, and the other end connects the inverse output terminal that power pins VCC, pull down resistor R2 one end connects driver D, and the other end connects grounding pin GND.
Because in the present invention, the mode of connection of the output port A of die and output port B and bus A and bus B is not how, after the Check up polarity and correction of polarity adaptation module, can ensure that driver input end mouth DI is identical with bus A with the phase place of receiver output port RO, and contrary with bus B.Therefore built-in pull-up resistor R1 and pull down resistor R2 can be added before the position of the polarity adaptation module of inside, so no matter how polarity switch combines, the result finally obtained, it is all the output port pull-up that same bus A is connected by pull-up resistor R1, pull down resistor R2 is by drop-down for the output port that same bus B is connected simultaneously, so just the external pull-up resistor of polarity RS-485 interface chip and pull down resistor is had to achieve same connected mode with of the prior art, what overcome nonpolarity RS-485 interface chip in prior art can not the weak point of prior external pull-up resistor and pull down resistor.
Particular circuit configurations of the present invention and principle of work is described in detail below according to embodiment.
As shown in Figure 3, on nonpolarity RS-485 interface chip with internal pull-up resistor R1 and pull down resistor R2 nonpolarity RS-485 interface chip basis in the prior art, the in-phase input end of the receiver R before polarity adaptation module connects pull-up resistor R1 to power pins VCC, at the anti-phase input termination pull down resistor R2 of receiver R to grounding pin GND.Because when bus A and bus B are connected to output port A and the output port B of RS-485 interface chip, concrete annexation is divided into two kinds, is described respectively below.
The first situation, when bus A links the output port A of chip, bus B links the output port B of chip.Judged by the polarity adaptation module of chi frame inside, switch S1 and switch S 4 can be allowed to disconnect, switch S 2 and switch S 3 close.The pull-up resistor R1 so just achieving chip internal is connected between bus A and power pins VCC, and pull down resistor R2 is connected between bus B and grounding pin GND.
The second situation, when bus A links the output port B of chip, bus B links the output port A of chip.Judged by the polarity adaptation module of chip internal, switch S2 and switch S 3 can be allowed to disconnect, switch S 1 and switch S 4 close.The same like this pull-up resistor R1 that can realize chip internal is connected between bus A and power pins VCC, and pull down resistor R2 is connected between bus B and grounding pin GND.
So, regardless of outside annexation, built-in pull-up resistor R1 and pull down resistor R2 all can normally work, and realizes function of the present invention.
Above-described is only the preferred embodiment of the present invention, the invention is not restricted to above embodiment.Be appreciated that the oher improvements and changes that those skilled in the art directly derive without departing from the spirit and concept in the present invention or associate, all should think and be included within protection scope of the present invention.
Claims (1)
1. the nonpolarity RS-485 interface chip with inner upper pull down resistor, comprises chi frame and the driver (D), receiver (R), the polarity adaptation module that are arranged in chi frame; Described chi frame also comprises power pins (VCC), grounding pin (GND), the first output port (A) and the second output port (B); Described polarity adaptation module comprises the first switch (S1), second switch (S2), the 3rd switch (S3) and the 4th switch (S4); The output terminal in the same way of described driver (D) connects the input end in the same way of receiver (R), and the inverse output terminal of driver (D) connects the reverse input end of receiver (R); Described first switch (S1) one end connects the output terminal in the same way of driver (D), and the other end connects the second output port (B); Described second switch (S2) one end connects the output terminal in the same way of driver (D), and the other end connects the first output port (A); Described 3rd switch (S3) one end connects the inverse output terminal of driver (D), and the other end connects the second output port (B); Described 4th switch (S4) one end connects the inverse output terminal of driver (D), and the other end connects the first output port (A); It is characterized in that: also comprise pull-up resistor (R1) and pull down resistor (R2), described pull-up resistor (R1) one end connects the output terminal in the same way of driver (D), the other end connects power pins (VCC), described pull down resistor (R2) one end connects the inverse output terminal of driver (D), and the other end connects grounding pin (GND).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410763434.7A CN104462000A (en) | 2014-12-11 | 2014-12-11 | Nonpolar RS-485 interface chip with internal pull-up and pull-down resistors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410763434.7A CN104462000A (en) | 2014-12-11 | 2014-12-11 | Nonpolar RS-485 interface chip with internal pull-up and pull-down resistors |
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| Publication Number | Publication Date |
|---|---|
| CN104462000A true CN104462000A (en) | 2015-03-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410763434.7A Pending CN104462000A (en) | 2014-12-11 | 2014-12-11 | Nonpolar RS-485 interface chip with internal pull-up and pull-down resistors |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111412630A (en) * | 2020-04-22 | 2020-07-14 | 珠海格力电器股份有限公司 | Communication interface control circuit and air conditioning unit |
| CN115098421A (en) * | 2022-06-30 | 2022-09-23 | 山东云海国创云计算装备产业创新中心有限公司 | Method and device for supporting parallel bus IO signal positive and negative connection |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6441595B1 (en) * | 2000-10-20 | 2002-08-27 | Sun Microsystems, Inc. | Universal compact PCI pull-up/termination IC |
| CN1766980A (en) * | 2004-10-25 | 2006-05-03 | 恩益禧电子股份有限公司 | Liquid crystal display for implmenting improved inversion driving technique |
| CN201584404U (en) * | 2009-11-12 | 2010-09-15 | 刘爱民 | Non-polar 485 chip |
| CN103236835A (en) * | 2013-04-09 | 2013-08-07 | 浙江威星智能仪表股份有限公司 | Signal isolation grid circuit |
| CN204256735U (en) * | 2014-12-11 | 2015-04-08 | 无锡新硅微电子有限公司 | The nonpolarity RS-485 interface chip of the inner upper pull down resistor of band |
-
2014
- 2014-12-11 CN CN201410763434.7A patent/CN104462000A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6441595B1 (en) * | 2000-10-20 | 2002-08-27 | Sun Microsystems, Inc. | Universal compact PCI pull-up/termination IC |
| CN1766980A (en) * | 2004-10-25 | 2006-05-03 | 恩益禧电子股份有限公司 | Liquid crystal display for implmenting improved inversion driving technique |
| CN201584404U (en) * | 2009-11-12 | 2010-09-15 | 刘爱民 | Non-polar 485 chip |
| CN103236835A (en) * | 2013-04-09 | 2013-08-07 | 浙江威星智能仪表股份有限公司 | Signal isolation grid circuit |
| CN204256735U (en) * | 2014-12-11 | 2015-04-08 | 无锡新硅微电子有限公司 | The nonpolarity RS-485 interface chip of the inner upper pull down resistor of band |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111412630A (en) * | 2020-04-22 | 2020-07-14 | 珠海格力电器股份有限公司 | Communication interface control circuit and air conditioning unit |
| CN115098421A (en) * | 2022-06-30 | 2022-09-23 | 山东云海国创云计算装备产业创新中心有限公司 | Method and device for supporting parallel bus IO signal positive and negative connection |
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| PB01 | Publication | ||
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| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20150325 |
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| RJ01 | Rejection of invention patent application after publication |