TTL and RS232 combined switching circuit
By designing a combined switching circuit for TTL and RS232, the problem of incorrect plug insertion of communication interfaces was solved, ensuring reliable connection and normal operation of electronic devices and protecting the signal transmission path.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SINO REAHER MEDICAL EQUIP CO LTD
- Filing Date
- 2025-04-21
- Publication Date
- 2026-05-01
AI Technical Summary
In the production of electronic devices, communication interface plugs are often inserted incorrectly, causing the equipment to malfunction.
Design a combined TTL and RS232 switching circuit to acquire the level signals of the communication interface function pins through a switching switch and control circuit, accurately connect the RS232 or TTL signal transceiver circuit, and avoid incorrect plugging.
It improves the reliability of electronic equipment, prevents signal reflection and damage to the control signal drive end, and ensures the correct connection of the communication interface.
Smart Images
Figure CN224190495U_ABST
Abstract
Description
A combined TTL and RS232 switching circuit Technical Field
[0001] This invention relates to the field of electronic circuits. More specifically, this invention relates to a combined switching circuit for TTL and RS232. Background Technology
[0002] To enable electronic devices to transmit and send data, their circuit boards typically feature various types of communication interfaces. A communication interface is a combination of hardware and software used for data transfer between devices. It defines how devices connect, the format, rate, and synchronization methods of the transmitted data.
[0003] In the production of electronic devices, a single circuit board typically has multiple communication interfaces, including TTL and RS232 interfaces. Production personnel need to plug the connectors into the corresponding interface sockets to ensure normal communication and operation of the electronic devices. However, incorrect plugging can easily occur, such as plugging a TTL connector into an RS232 connector socket, or vice versa, which can cause the electronic devices to malfunction. Summary of the Invention
[0004] To address the technical problem in the prior art where the communication interface plug is easily inserted incorrectly during the manufacturing process of electronic devices, causing the electronic devices to malfunction, the present invention provides a solution in the following aspects.
[0005] In a first aspect, the present invention provides a combined TTL and RS232 switching circuit, comprising:
[0006] The changeover switch has a first moving contact for connecting to the transmit pin of the communication interface, a second moving contact for connecting to the receive pin of the communication interface, a first stationary contact and a second stationary contact for connecting to the receive end and the transmit end of the RS 232 signal transceiver circuit, respectively, and a third stationary contact and a fourth stationary contact for connecting to the receive end and the transmit end of the TTL signal transceiver circuit, respectively.
[0007] The control circuit is used to acquire the function pins of the communication interface and control the connection to the changeover switch. When the signal output by the function pin is high, it controls the first moving contact of the changeover switch to connect with the first stationary contact and the second moving contact to connect with the second stationary contact; when the signal output by the function pin is low, it controls the first moving contact of the changeover switch to connect with the third stationary contact and the second moving contact to connect with the fourth stationary contact. The communication interface is an RS232 communication interface or a TTL communication interface. The signal output by the function pin of the RS232 communication interface is high, and the signal output by the function pin of the TTL communication interface is low.
[0008] Preferably, the third stationary contact is connected to the receiving end of the TTL signal transceiver circuit through the first current-limiting resistor, and the fourth stationary contact is connected to the transmitting end of the TTL signal transceiver circuit through the second current-limiting resistor.
[0009] Preferably, the changeover switch is a double-pole double-position signal relay, the control circuit includes a control switch, one end of the coil of the double-pole double-position signal relay is grounded, and the other end is connected to the power supply through the control switch, and the controlled end of the control switch is connected to the function pin.
[0010] Preferably, the model of the double-pole double-position signal relay is G6K-2F-Y-TR DC5.
[0011] Preferably, the control switch is a transistor.
[0012] Preferably, a third current-limiting resistor is connected in series between the controlled terminal of the control switch and the functional pin.
[0013] Preferably, it also includes a wire-to-board socket, wherein the second pin of the wire-to-board socket is connected to the first moving contact and is also used to connect to the transmitting pin of the communication interface; its third pin is connected to the second moving contact and is also used to connect to the receiving pin of the communication interface; and its fourth pin is connected to the controlled end of the control switch and is also used to connect to the functional pin.
[0014] Preferably, the TTL signal transceiver circuit is a microcontroller, and both the third stationary contact and the fourth stationary contact are connected to the microcontroller.
[0015] Preferably, the RS232 signal transceiver circuit includes a TTL to RS232 chip, the input pin of the second transmitter of the TTL to RS232 chip is connected to the receiving end of the TTL signal transceiver circuit, the output pin of the second transmitter is connected to the second stationary contact, the input pin of the second receiver of the TTL to RS232 chip is connected to the first stationary contact, and the output pin of the second receiver is connected to the transmitting end of the TTL signal transceiver circuit.
[0016] Preferably, the TTL to RS232 converter chip is model SP232EEN-L / TR.
[0017] The technical advantages of this invention are as follows: By setting up a changeover switch, one set of moving contacts of the changeover switch is used to connect to the transmit and receive pins of the communication interface, and the two sets of stationary contacts of the changeover switch are respectively connected to the RS232 signal transceiver circuit and the TTL signal transceiver circuit. A control circuit is set up to collect the level signals of the functional pins of the communication interface and act according to the high or low level signals. This achieves accurate connection of the RS232 communication interface to the RS232 signal transceiver circuit and the TTL communication interface to the TTL signal transceiver circuit, thereby avoiding the problem of incorrect plug insertion of the communication interface during the production of electronic equipment, and thus improving the operational reliability of the manufactured electronic equipment.
[0018] Furthermore, by connecting the third and fourth stationary contacts of the changeover switch to the TTL signal transceiver circuit through two current-limiting resistors, the communication interface can be protected and signal reflection can be prevented.
[0019] Furthermore, by connecting a third current-limiting resistor in series with the controlled terminal of the control switch, the control signal can be protected to prevent excessive current from damaging the control signal drive terminal, thereby protecting the control signal drive terminal.
[0020] Furthermore, by setting up a wire-to-board socket, the switching circuit of this utility model can be easily connected to the communication interface. Attached Figure Description
[0021] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:
[0022] Figure 1 is a schematic diagram of the combined switching circuit of TTL and RS232 according to an embodiment of the present invention. Detailed Implementation
[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0025] Example of a combined TTL and RS232 switching circuit:
[0026] As shown in Figure 1, the combined TTL and RS232 switching circuit of the present invention includes:
[0027] The changeover switch K1 has a first moving contact 6 for connecting to the transmit pin of the communication interface, a second moving contact 3 for connecting to the receive pin of the communication interface, a first stationary contact 5 and a second stationary contact 4 for connecting to the receive end and transmit end of the RS232 signal transceiver circuit respectively, and a third stationary contact 7 and a fourth stationary contact 2 for connecting to the receive end and transmit end of the TTL signal transceiver circuit respectively.
[0028] The control circuit is used to acquire the function pins of the communication interface and control the connection to the changeover switch. When the signal output by the function pin is high, it controls the first moving contact of the changeover switch to connect with the first stationary contact and the second moving contact to connect with the second stationary contact; when the signal output by the function pin is low, it controls the first moving contact of the changeover switch to connect with the third stationary contact and the second moving contact to connect with the fourth stationary contact. The communication interface is an RS232 communication interface or a TTL communication interface. The signal output by the function pin of the RS232 communication interface is high, and the signal output by the function pin of the TTL communication interface is low.
[0029] A changeover switch is an electrical component used to control the direction of current flow or the connection state of a circuit. A changeover switch includes a contact system, a coil, and a housing. The contact system consists of multiple sets of stationary contacts and one set of moving contacts. Before the coil is energized, the moving contacts are connected to one set of stationary contacts. When the coil is energized, the moving contacts actuate, changing their state to connect to another set of stationary contacts. The housing of the changeover switch protects the internal contacts and coil from external environmental factors (such as dust and moisture). The housing is typically made of insulating materials, such as plastic or ceramic, to ensure safe operation.
[0030] The working principle of this utility model is as follows: If the two moving contacts of the changeover switch K1 are connected to the RS232 communication interface, since the signal output by its function pin is high level, the control circuit will connect the first moving contact of the changeover switch to the first stationary contact and the second moving contact to the second stationary contact, thereby connecting the RS232 communication interface to the RS232 signal transceiver circuit; if the two moving contacts of the changeover switch K1 are connected to the TTL communication interface, since the signal output by its function pin is low level, the control circuit will connect the first moving contact of the changeover switch to the third stationary contact and the second moving contact to the fourth stationary contact, thereby connecting the TTL communication interface to the TTL signal transceiver circuit.
[0031] This invention utilizes a changeover switch, where one set of moving contacts is connected to the transmit / receive pins of the communication interface, and the two sets of stationary contacts are connected to the RS232 and TTL signal transceiver circuits respectively. A control circuit collects the level signals of the functional pins of the communication interface and operates accordingly based on the high or low level signals. This ensures accurate connection between the RS232 communication interface and the TTL communication interface, avoiding the common problem of incorrect plug placement during the manufacturing process and improving the reliability of the produced electronic equipment.
[0032] In one embodiment, the third stationary contact 7 is connected to the receiving end of the TTL signal transceiver circuit through the first current-limiting resistor R6, and the fourth stationary contact 2 is connected to the transmitting end of the TTL signal transceiver circuit through the second current-limiting resistor R7.
[0033] By connecting the third and fourth stationary contacts of the changeover switch to the TTL signal transceiver circuit through two current-limiting resistors, the communication interface can be protected and signal reflection can be prevented.
[0034] In one embodiment, the changeover switch is a double-pole double-position signal relay, the control circuit includes a control switch, one end of the coil of the double-pole double-position signal relay is grounded, and the other end is connected to the power supply through the control switch, and the controlled end of the control switch is connected to the function pin.
[0035] A double-pole double-throw signal relay is a type of relay with two sets of normally open contacts and two sets of normally closed contacts, capable of switching two switches simultaneously. A double-pole double-throw signal relay includes a contact system, an electromagnetic coil, and a mechanical structure. The contact system consists of two independent sets of contacts, each set comprising a common terminal (COM), a normally open terminal (NO), and a normally closed terminal (NC). When the coil is energized, it generates a magnetic field that attracts the armature, causing the contacts to switch. The mechanical structure includes components such as the armature and springs, used to physically switch the contacts. When the relay is not energized, the common terminals of the two sets of contacts are connected to their respective normally closed terminals, and the normally open terminals are in an open state. When the relay coil is energized, the coil generates a magnetic field that attracts the armature, causing the contacts to switch, connecting the common terminal to the normally open terminal and disconnecting the normally closed terminal.
[0036] In this embodiment, a transistor is used as the control switch. In other embodiments, other fully controllable switching devices may also be used as the control switch.
[0037] The transistor can be either an NPN transistor or a PNP transistor.
[0038] In one embodiment, the double-pole double-throw signal relay is model G6K-2F-Y-TR DC5. In other embodiments, other suitable models of double-pole double-throw signal relays may also be used.
[0039] In one embodiment, a third current-limiting resistor R8 is connected in series between the controlled terminal of the control switch and the functional pin.
[0040] By connecting a third current-limiting resistor in series with the controlled terminal of the control switch, the control signal can be protected to prevent excessive current from damaging the control signal drive terminal, thereby protecting the control signal drive terminal.
[0041] In one embodiment, the device further includes a wire-to-board socket U5, wherein the second pin of the wire-to-board socket is connected to the first moving contact 6 and is also used to connect to the transmitting pin of the communication interface; its third pin is connected to the second moving contact 3 and is also used to connect to the receiving pin of the communication interface; and its fourth pin is connected to the controlled end of the control switch and is also used to connect to the functional pin.
[0042] A wire-to-board (FTB) connector is an electronic connector used to connect wires to a circuit board (PCB). It primarily achieves the connection between the wire and the circuit board through a plug and a socket, providing reliable electrical connection and mechanical support. A FTB connector typically consists of a plug, a socket, and a locking mechanism; the plug connects to one end of the wire and typically consists of metal leads and an insulating shell. The socket is mounted on the circuit board and typically consists of metal leads and an insulating shell. The locking mechanism ensures a secure connection between the plug and socket, preventing loosening due to vibration or external force. The FTB connector achieves electrical connection through the connection of the plug and socket. In this embodiment, the socket can be mounted on the circuit board where the communication interface is located, and the corresponding metal leads of the socket connect to the corresponding leads of the communication interface.
[0043] By setting up a wire-to-board socket, the switching circuit of this utility model can be easily connected to the communication interface.
[0044] In one embodiment, the TTL signal transceiver circuit is a microcontroller U2, and the third stationary contact and the fourth stationary contact are both connected to the microcontroller.
[0045] In one embodiment, the RS232 signal transceiver circuit includes a TTL to RS232 chip U1. The input pin T2IN of the second transmitter of the TTL to RS232 chip is connected to the receiving end of the TTL signal transceiver circuit, and the output pin T2OUT of the second transmitter is connected to the second stationary contact. The input pin R2IN of the second receiver of the TTL to RS232 chip is connected to the first stationary contact, and the output pin R2OUT of the second receiver is connected to the transmitting end of the TTL signal transceiver circuit.
[0046] In this embodiment, the TTL to RS232 converter chip is model SP232EEN-L / TR. In other embodiments, other suitable TTL to RS232 converter chips can also be used.
[0047] In the foregoing description of this specification, unless otherwise expressly specified and limited, the terms "connection" and similar terms should be interpreted broadly. For example, the term "connection" can refer to a direct link, an indirect link via an intermediate medium, or the internal connection of two elements or the interaction between two elements. Therefore, unless otherwise expressly limited in this specification, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0048] The terms "first" or "second," etc., used to designate numbers or ordinal numbers in this specification are for descriptive purposes only and should not be construed as indicating, explicitly or implicitly, relative importance or specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this specification, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.
[0049] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.
Claims
1. A combined TTL and RS232 switching circuit, characterized in that, include: A changeover switch has a first moving contact connected to the transmit pin of the communication interface, a second moving contact connected to the receive pin of the communication interface, a first stationary contact and a second stationary contact connected to the receive and transmit ends of an RS-232 signal transceiver circuit, respectively, and a third stationary contact and a fourth stationary contact connected to the receive and transmit ends of a TTL signal transceiver circuit, respectively. A control circuit is used to acquire data from the function pins connected to the communication interface and control the changeover switch. When the signal output by the function pin is high, the first moving contact of the changeover switch connects to the first stationary contact, and the second moving contact connects to the second stationary contact; when the signal output by the function pin is low, the first moving contact connects to the third stationary contact, and the second moving contact connects to the fourth stationary contact. The communication interface is either an RS-232 communication interface or a TTL communication interface. The signal output by the function pin of the RS-232 communication interface is high, and the signal output by the function pin of the TTL communication interface is low.
2. The combined TTL and RS232 switching circuit as described in claim 1, characterized in that, The third stationary contact is connected to the receiving end of the TTL signal transceiver circuit through the first current-limiting resistor, and the fourth stationary contact is connected to the transmitting end of the TTL signal transceiver circuit through the second current-limiting resistor.
3. The combined TTL and RS232 switching circuit as described in claim 1, characterized in that, The changeover switch uses a double-pole double-position signal relay. The control circuit includes a control switch. One end of the coil of the double-pole double-position signal relay is grounded, and the other end is connected to the power supply through the control switch. The controlled end of the control switch is connected to the function pin.
4. The combined TTL and RS232 switching circuit as described in claim 3, characterized in that, The model of the double-pole double-position signal relay is G6K-2F-Y-TR DC5.
5. The combined TTL and RS232 switching circuit as described in claim 3, characterized in that, The control switch uses a transistor.
6. The combined TTL and RS232 switching circuit as described in claim 3, characterized in that, A third current-limiting resistor is connected in series between the controlled terminal of the control switch and the functional pin.
7. The combined TTL and RS232 switching circuit as described in claim 3, characterized in that, It also includes a wire-to-board socket, wherein the second pin of the wire-to-board socket is connected to the first moving contact and is also used to connect the transmitting pin of the communication interface; its third pin is connected to the second moving contact and is also used to connect the receiving pin of the communication interface; and its fourth pin is connected to the controlled end of the control switch and is also used to connect the functional pin.
8. The combined TTL and RS232 switching circuit as described in claim 1, characterized in that, The TTL signal transceiver circuit is a microcontroller, and both the third and fourth stationary contacts are connected to the microcontroller.
9. The combined TTL and RS232 switching circuit as described in any one of claims 1 to 8, characterized in that, The RS232 signal transceiver circuit includes a TTL to RS232 chip. The input pin of the second transmitter of the TTL to RS232 chip is connected to the receiving end of the TTL signal transceiver circuit, and the output pin of the second transmitter is connected to the second stationary contact. The input pin of the second receiver of the TTL to RS232 chip is connected to the first stationary contact, and the output pin of the second receiver is connected to the transmitting end of the TTL signal transceiver circuit.
10. The combined TTL and RS232 switching circuit as described in claim 9, characterized in that, The TTL to RS232 converter chip is model SP232EEN-L / TR.