An RS485-based program burning circuit and a program burning method

Abstract

The present application discloses a program burning circuit and a program burning method based on RS485. An RS485 communicator externally connected through an Ethernet interface terminal in the device is adopted. An OTA download recognition circuit is provided between a first pin triggered after being connected by an OTA download line in the Ethernet interface terminal and an OTA download recognition signal receiving end of a processor. An RS485 enabling circuit is provided between a data sending interface of the processor and a receiving enabling end of the RS485 communicator. After the processor of the device to be burned recognizes a level representing an OTA download recognition signal output by the OTA download recognition circuit, the RS485 communicator is enabled through the RS485 enabling circuit, so as to receive a program burning signal by using the RS485 communicator and the OTA download line, realizing receiving program burning through the RS485 communicator, thereby enabling the work of program burning and updating without opening the chassis.

Description

Technical Field

[0001] The present application relates to the field of program burning, and particularly to a program burning circuit and a program burning method based on RS485. Background Art

[0002] Currently, software downloading of a device processor requires a separate interface to download and update programs. Usually, the interface for program downloading has no external connection, resulting in the need to open the chassis, find the software downloading interface of the board card, and then perform the download when performing software updates, which is very inconvenient after the device is encapsulated.

[0003] Providing a solution for facilitating device program burning is a technical problem that those skilled in the art need to solve. Summary of the Invention

[0004] The purpose of the present application is to provide a program burning circuit and a program burning method based on RS485, which can perform program burning work without opening the device chassis to find the software downloading interface of the board card.

[0005] To solve the above technical problems, the present application provides a program burning circuit based on RS485, including: an Ethernet interface terminal, an OTA download recognition circuit, an RS485 communicator, and an RS485 enable circuit;

[0006] Wherein, a first pin triggered after being connected by an OTA download line in the Ethernet interface terminal is connected to an input end of the OTA download recognition circuit, an output end of the OTA download recognition circuit is connected to an OTA download recognition signal receiving end of a processor, a data pin in the Ethernet interface terminal is connected to a slave-end data interface of the RS485 communicator, and a host-end data interface of the RS485 communicator is correspondingly connected to a data sending interface and a data receiving interface of the processor;

[0007] The RS485 enable circuit is an inverter circuit, an input end of the RS485 enable circuit is connected to the data sending interface of the processor, and an output end of the RS485 enable circuit is connected to a receive enable end of the RS485 communicator;

[0008] The OTA download recognition circuit is used to output different levels when the OTA download line is connected to the Ethernet interface terminal and when the OTA download line is not connected to the Ethernet interface terminal, so that after the processor receives the level representing the OTA download recognition signal output by the OTA download recognition circuit, the RS485 communicator is enabled through the RS485 enable circuit to receive a program burning signal by using the RS485 communicator and the OTA download line.

[0009] Optionally, the OTA download recognition circuit specifically includes a first resistor, a second resistor, a third resistor, and a first triode;

[0010] Wherein, a first end of the first resistor is connected to the first pin, a second end of the first resistor is connected to a base of the first triode, a collector of the first triode, a second end of the second resistor, and a first end of the third resistor are connected, a first end of the second resistor is connected to a first DC power supply, a second end of the third resistor is connected to an OTA download recognition signal receiving end of the processor, and an emitter of the first triode is grounded.

[0011] Optionally, an external communication recognition circuit is further included;

[0012] Wherein, an input end of the external communication recognition circuit is connected to a second pin triggered after being connected to an external communication device in the Ethernet interface terminal, and an output end of the external communication recognition circuit is connected to an external communication recognition signal receiving end of the processor; the external communication recognition circuit is configured to output different levels when the Ethernet interface terminal is connected to an external communication device and when the Ethernet interface terminal is not connected to the external communication device.

[0013] Optionally, the external communication recognition circuit specifically includes a fourth resistor, a fifth resistor, and a first capacitor;

[0014] Wherein, a first end of the fourth resistor is grounded, a second end of the fourth resistor, a first end of the fifth resistor are connected to the second pin, a second end of the fifth resistor, a first end of the first capacitor are connected to an external communication recognition signal receiving end of the processor, and a second end of the first capacitor is grounded.

[0015] To solve the above technical problems, the present application further provides an RS485-based program burning method, based on a processor, including:

[0016] After the OTA download recognition signal receiving end of the processor receives a level representing an OTA download recognition signal output by the OTA download recognition circuit, an enable signal is sent through a data sending interface of the processor via an RS485 enable circuit to activate a receive enable of the RS485 communicator;

[0017] Receiving a program burning signal of the RS485 data bus through the RS485 communicator;

[0018] Among them, the OTA download recognition signal receiving end of the processor is connected to the output end of the OTA download recognition circuit. The input end of the OTA download recognition circuit is connected to the first pin triggered after being connected to the OTA download line in the Ethernet interface terminal. The data pins in the Ethernet interface terminal are connected to the slave-end data interface of the RS485 communicator. The host-end data interface of the RS485 communicator is correspondingly connected to the data sending interface and the data receiving interface of the processor;

[0019] The RS485 enabling circuit is an inverter circuit. The input end of the RS485 enabling circuit is connected to the data sending interface of the processor. The output end of the RS485 enabling circuit is connected to the receive enabling end of the RS485 communicator;

[0020] The OTA download recognition circuit is used to output different levels when the OTA download line is connected to the Ethernet interface terminal and when the OTA download line is not connected to the Ethernet interface terminal.

[0021] Optionally, the OTA download recognition circuit specifically includes a first resistor, a second resistor, a third resistor, and a first triode;

[0022] Among them, the first end of the first resistor is connected to the first pin. The second end of the first resistor is connected to the base of the first triode. The collector of the first triode, the second end of the second resistor, and the first end of the third resistor are connected. The first end of the second resistor is connected to a first DC power supply. The second end of the third resistor is connected to the OTA download recognition signal receiving end of the processor. The emitter of the first triode is grounded.

[0023] Optionally, it further includes:

[0024] When the external communication recognition signal receiving end of the processor receives the level output by the external communication recognition circuit indicating that the Ethernet interface terminal is connected to an external communication device, it controls the RS485 communicator to enter the external communication mode;

[0025] Among them, the input end of the external communication recognition circuit is connected to the second pin triggered after being connected to the external communication device in the Ethernet interface terminal. The output end of the external communication recognition circuit is connected to the external communication recognition signal receiving end of the processor; the external communication recognition circuit is used to output different levels when the Ethernet interface terminal is connected to the external communication device and when the Ethernet interface terminal is not connected to the external communication device.

[0026] Optionally, the external communication recognition circuit specifically includes a fourth resistor, a fifth resistor, and a first capacitor;

[0027] Wherein, the first end of the fourth resistor is grounded, the second end of the fourth resistor, the first end of the fifth resistor are connected to the second pin, the second end of the fifth resistor, the first end of the first capacitor are connected to the external communication identification signal receiving end of the processor, and the second end of the first capacitor is grounded.

[0028] For the program burning circuit based on RS485 provided by this application, an RS485 communicator externally connected through an Ethernet interface terminal in the device is adopted. An OTA download identification circuit is arranged between the first pin triggered after being connected by an OTA download line in the Ethernet interface terminal and the OTA download identification signal receiving end of the processor, so as to output different levels when the Ethernet interface terminal is connected to the OTA download line and when the Ethernet interface terminal is not connected to the OTA download line; an RS485 enabling circuit is arranged between the data sending interface of the processor and the receiving enabling end of the RS485 communicator; thus, after the program burning device is connected to the Ethernet interface terminal of the device to be burned through the OTA download line, after the processor of the device to be burned identifies the level representing the OTA download identification signal output by the OTA download identification circuit, the RS485 communicator is enabled through the RS485 enabling circuit, so as to receive the program burning signal by using the RS485 communicator and the OTA download line, realizing receiving the program burning through the RS485 communicator, and thus the work of program burning and updating can be carried out without opening the device chassis.

[0029] This application also provides a program burning method based on RS485, which has the above beneficial effects and will not be elaborated here. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0031] Figure 1 It is the circuit diagram of the first part of a program burning circuit based on RS485 provided by an embodiment of this application;

[0032] Figure 2 It is the circuit diagram of the second part of a program burning circuit based on RS485 provided by an embodiment of this application. Detailed Embodiments

[0033] The core of this application is to provide a program burning circuit and a program burning method based on RS485, which can carry out the program burning work without opening the device chassis to find the software download interface of the board.

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0035] Figure 1 It is a circuit diagram of the first part of a program burning circuit based on RS485 provided by an embodiment of the present application; Figure 2 It is a circuit diagram of the second part of a program burning circuit based on RS485 provided by an embodiment of the present application.

[0036] It should be noted that, Figure 1 and Figure 2 together constitute a program burning circuit based on RS485 in an embodiment of the present application.

[0037] As Figure 1 and Figure 2 shown, the program burning circuit based on RS485 provided by the embodiment of the present application is characterized by including: an Ethernet interface terminal J1, an OTA download identification circuit, an RS485 communicator U3, and an RS485 enabling circuit;

[0038] Among them, the first pin triggered after the OTA download line is connected in the Ethernet interface terminal J1 is connected to the input end of the OTA download identification circuit, the output end BOOT0 of the OTA download identification circuit is connected to the OTA download identification signal receiving end of the processor, the data pins in the Ethernet interface terminal J1 are connected to the slave end data interfaces A and B of the RS485 communicator U3, and the host end data interfaces D and R of the RS485 communicator U3 are correspondingly connected to the data sending interface TXD of the processor and the data receiving interface RXD of the processor;

[0039] The RS485 enabling circuit is an inverter circuit, the input end of the RS485 enabling circuit is connected to the data sending interface TXD of the processor, and the output end of the RS485 enabling circuit is connected to the receive enable end RE and the driver enable end DE of the RS485 communicator U3;

[0040] The OTA download identification circuit is used to output different levels when the OTA download line is connected to the Ethernet interface terminal J1 and when the OTA download line is not connected to the Ethernet interface terminal J1, so that the processor enables the RS485 communicator U3 through the RS485 enabling circuit after receiving the level representing the OTA download identification signal output by the OTA download identification circuit, so as to receive the program burning signal by using the RS485 communicator U3 and the OTA download line.

[0041] In the embodiments of the present application, considering that there are usually Ethernet interface terminals left on the device for external communication, the Ethernet interface terminal is selected as the download port, and the program download and update can be realized without unpacking the device through the RS485 communicator and the Ethernet interface terminal.

[0042] OTA, namely Over-the-Air Technology (abbreviated as "OTA" in this article), is a technology for remotely managing the data of mobile terminal devices and SIM cards through the air interface of mobile communication. In the embodiments of the present application, the interface of the OTA download line is used to trigger a specific pin of the Ethernet interface terminal, and an OTA download recognition circuit is set between the specific pin and the OTA download recognition signal receiving end of the processor, so that the processor is triggered by the signal connected to the Ethernet interface terminal by the OTA download line to inform the processor that program burning is to be performed.

[0043] The program burning can be the program burning during software update in the process of using the device, or the program burning when the device is first put into use. When the device is first put into use, there is no control program for the rest of the hardware of the device in the processor, and the RS485 communicator needs to be activated to receive the program burning signal. Therefore, in the embodiments of the present application, an RS485 enabling circuit is set between the data sending port TXD of the processor and the receiving enable end RE and DE of the RS485 communicator U3.

[0044] Using the RS485-based program burning circuit provided by the embodiments of the present application, when the device is first put into use, connect the program burning device to the Ethernet interface terminal J1 reserved for program burning of the device to be burned through the OTA download line, and the OTA download line triggers the first pin of the Ethernet interface terminal J1 (such as Figure 1 pin1 of J1 in the figure), thereby triggering the OTA download recognition circuit to output a level representing the OTA download recognition signal.

[0045] In a specific implementation, the OTA download recognition circuit can be implemented by a switching circuit. Taking the Ethernet interface terminal J1 as an RJ45 as an example, its pin1 will be pulled low after the OTA download line is inserted. Using pin1 as the first pin defined in this article, a switching circuit can be designed to send the OTA download recognition signal to the processor.

[0046] Such as Figure 1 shown, the OTA download recognition circuit J1 can specifically include a first resistor R13, a second resistor R12, a third resistor R5, and a first triode Q1;

[0047] Among them, the first end of the first resistor R13 is connected to the first pin, the second end of the first resistor R13 is connected to the base of the first triode Q1, the collector of the first triode Q1, the second end of the second resistor R12 and the first end of the third resistor R5 are connected, and the first end of the second resistor R12 is connected to the first DC power supply (such as Figure 1 the +3.3V DC power supply shown) is connected, the second end of the third resistor R5 is connected to the OTA download identification signal receiving end of the processor, and the emitter of the first triode Q1 is grounded.

[0048] In existing devices, if the Ethernet interface terminal J1 is RJ45, its pin1 was originally only connected to the +5V DC power supply. On this basis, the OTA download identification circuit shown in Figure 1 is added in this embodiment of the present application. When no interface is connected to the Ethernet interface terminal J1, the output end BOOT0 of the OTA download identification circuit defaults to a low level. After the OTA download line is connected to the Ethernet interface terminal J1, the first pin pin1 is pulled low, and the output end BOOT0 of the OTA download identification circuit is pulled high. When the processor detects that this signal is valid, it is identified as OTA download and enters the serial port download mode.

[0049] The connection circuit of the RS485 communicator U3 is as shown in Figure 2 : The pin2 of the Ethernet interface terminal J1 is connected to the second end of the inductor L1 through the data bus A. The first end of the inductor L1, the first end of the capacitor C10, the second end of the resistor R9, and the first end of the capacitor C11 are connected to the slave data interface A of the RS485 communicator U3. The first end of the resistor R9 is connected to the +5V DC power supply, and the first end of the capacitor C10 is grounded. The pin7 of the Ethernet interface terminal is connected to the second end of the inductor L2 through the data bus B. The first end of the inductor L2, the first end of the capacitor C9, the second end of the capacitor C11, and the first end of the resistor R10 are connected to the slave data interface B of the RS485 communicator U3. The second end of the resistor R10 and the second end of the capacitor C9 are grounded. The host data interface D of the RS485 communicator U3 is connected to the second end of the resistor R3. The first end of the capacitor R3 and the second end of the capacitor R7 are connected to the data sending interface TXD of the processor; the host data interface R of the RS485 communicator U3 is connected to the second end of the resistor R8 and the input end of the inverter U1. The first end of the resistor R8 is connected to the +5V DC power supply, the output end of the inverter U1 is connected to the input end of the inverter U2, and the output end of the inverter U2 is connected to the data receiving interface RXD of the processor through the resistor R4.

[0050] In the bus communication of the RS485 communicator U3, the data is valid at a low level. Therefore, after the processor receives the OTA download identification signal, it enables the signal RTS to be input to the receive enable terminals RE and DE of the RS485 communicator U3 through the RS485 enable circuit (an inverter circuit composed of the inverter U2 and the resistor R6), enabling the RS485 communicator U3 to enter the receive mode. The program burning signal can be received through the AB data bus to complete the software update, and the entire process does not require opening the device chassis.

[0051] To save board space and adapt to the trend of device miniaturization, since the RS485 communicator is often used for communication connection with external communication devices, the RS485 communicator for external communication can be reused as the RS485 communicator U3 for program burning. Based on the above embodiments, the RS485-based program burning circuit provided by the embodiments of the present application further includes an external communication identification circuit;

[0052] Among them, the input end of the external communication identification circuit is connected to the second pin triggered after being connected to an external communication device in the Ethernet interface terminal J1, and the output end of the external communication identification circuit is connected to the external communication identification signal receiving end of the processor; the external communication identification circuit is used to output different levels when the Ethernet interface terminal J1 is connected to an external communication device and when the Ethernet interface terminal J1 is not connected to an external communication device.

[0053] In a specific implementation, as Figure 1 shown, the external communication identification circuit may specifically include a fourth resistor R1, a fifth resistor R2, and a first capacitor C2;

[0054] Among them, the first end of the fourth resistor R1 is grounded, the second end of the fourth resistor R1 and the first end of the fifth resistor R2 are connected to the second pin, the second end of the fifth resistor R2 and the first end of the first capacitor C2 are connected to the external communication identification signal receiving end of the processor, and the second end of the first capacitor C2 is grounded.

[0055] Taking the Ethernet interface terminal J1 as an RJ45 as an example, the second pin defined herein is pin8 of the RJ45. After connecting an external communication device, pin8 of the RJ45 is pulled high. After the external communication identification signal receiving end of the processor receives the signal RJ45_SEL and identifies it as valid, it is confirmed as external communication.

[0056] Based on the RS485-based program burning circuit provided by the embodiments of the present application, when the RS485 communicator U3 is in the receive mode, the data signal TXD transmitted by the processor is default high level, then the enable signal RTS of the RS485 communicator U3 is low level for receive enable, and the data on the AB data bus is converted by the RS485 communicator U3 into the processor receive signal RXD and sent to the processor.

[0057] In the transmission mode of RS485, when TXD is the data signal, RTS is the data signal with changing high and low levels. The RS485 communicator U3 will switch between the transmission and reception modes. It should be noted that in RS485 communication, the data is low-valid. When TXD is low, RTS is high. At this time, the RS485 communicator U3 enables transmission, and the TXD data signal is transmitted to the AB data bus through the RS485 communicator U3. When TXD is high, RTS is low, and the RS485 communicator U3 will enter the reception mode. However, at this time, it is in the transmission mode for the processor, and no data will be received at this time, so the received data will not cause interference to the processor.

[0058] The above text details each embodiment corresponding to the program burning circuit based on RS485. On this basis, the present application also discloses a program burning method based on RS485 corresponding to the program burning circuit based on RS485.

[0059] Based on the processor, the program burning method based on RS485 provided by the embodiments of the present application includes:

[0060] When the OTA download identification signal receiving end of the processor receives the level representing the OTA download identification signal output by the OTA download identification circuit, an enabling signal is sent through the data sending interface of the processor via the RS485 enabling circuit to activate the reception enabling of the RS485 communicator;

[0061] Receive the program burning signal of the RS485 data bus through the RS485 communicator;

[0062] Among them, the OTA download identification signal receiving end of the processor is connected to the output end of the OTA download identification circuit. The input end of the OTA download identification circuit is connected to the first pin triggered after the OTA download line is connected to the Ethernet interface terminal. The data pin in the Ethernet interface terminal is connected to the slave end data interface of the RS485 communicator. The host end data interface of the RS485 communicator is correspondingly connected to the data sending interface and the data receiving interface of the processor;

[0063] The RS485 enabling circuit is an inverter circuit. The input end of the RS485 enabling circuit is connected to the data sending interface of the processor, and the output end of the RS485 enabling circuit is connected to the reception enabling end of the RS485 communicator;

[0064] The OTA download identification circuit is used to output different levels when the OTA download line is connected to the Ethernet interface terminal and when the OTA download line is not connected to the Ethernet interface terminal.

[0065] In a specific implementation, the OTA download identification circuit may specifically include a first resistor, a second resistor, a third resistor, and a first triode;

[0066] Among them, the first end of the first resistor is connected to the first pin, the second end of the first resistor is connected to the base of the first triode, the collector of the first triode, the second end of the second resistor and the first end of the third resistor are connected, the first end of the second resistor is connected to the first DC power supply, the second end of the third resistor is connected to the OTA download identification signal receiving end of the processor, and the emitter of the first triode is grounded.

[0067] Furthermore, the RS485-based program burning method provided by the embodiments of the present application may further include:

[0068] When the external communication identification signal receiving end of the processor receives the level output by the external communication identification circuit indicating that the Ethernet interface terminal is connected to an external communication device, control the RS485 communicator to enter the external communication mode;

[0069] Among them, the input end of the external communication identification circuit is connected to the second pin triggered after being connected to the external communication device in the Ethernet interface terminal, and the output end of the external communication identification circuit is connected to the external communication identification signal receiving end of the processor; the external communication identification circuit is used to output different levels when the Ethernet interface terminal is connected to an external communication device and when the Ethernet interface terminal is not connected to an external communication device.

[0070] In a specific implementation, the external communication identification circuit specifically includes a fourth resistor, a fifth resistor and a first capacitor;

[0071] Among them, the first end of the fourth resistor is grounded, the second end of the fourth resistor, the first end of the fifth resistor are connected to the second pin, the second end of the fifth resistor, the first end of the first capacitor are connected to the external communication identification signal receiving end of the processor, and the second end of the first capacitor is grounded.

[0072] Since the embodiments of the RS485-based program burning method part correspond to the embodiments of the RS485-based program burning circuit part, please refer to the description of the embodiments of the RS485-based program burning circuit part for the embodiments of the RS485-based program burning method part, which will not be elaborated here.

[0073] The above has introduced in detail a program burning circuit and a program burning method based on RS485 provided by the present application. The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the program burning method based on RS485 disclosed in the embodiment, since it corresponds to the program burning circuit based on RS485 disclosed in the embodiment, the description is relatively simple. For the relevant parts, reference can be made to the description of the program burning circuit based on RS485. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0074] It should also be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

Claims

1. A program burning circuit based on RS485, characterized in that, Comprising: An Ethernet interface terminal, an OTA download recognition circuit, an RS485 communicator, and an RS485 enable circuit; Wherein, a first pin triggered after being connected by an OTA download line in the Ethernet interface terminal is connected to the input end of the OTA download recognition circuit, the output end of the OTA download recognition circuit is connected to the OTA download recognition signal receiving end of the processor, a data pin in the Ethernet interface terminal is connected to the slave-end data interface of the RS485 communicator, and the host-end data interface of the RS485 communicator is correspondingly connected to the data sending interface and the data receiving interface of the processor; The RS485 enable circuit is an inverter circuit, the input end of the RS485 enable circuit is connected to the data sending interface of the processor, and the output end of the RS485 enable circuit is connected to the receive enable end of the RS485 communicator; The OTA download recognition circuit is used to output different levels when the Ethernet interface terminal is connected to the OTA download line and when the Ethernet interface terminal is not connected to the OTA download line, so that after the processor receives the level representing the OTA download recognition signal output by the OTA download recognition circuit, the RS485 communicator is enabled through the RS485 enable circuit, and the program burning signal is received by using the RS485 communicator and the OTA download line; The OTA download recognition circuit specifically includes a first resistor, a second resistor, a third resistor, and a first triode; Wherein, a first end of the first resistor is connected to the first pin, a second end of the first resistor is connected to the base of the first triode, the collector of the first triode, a second end of the second resistor, and a first end of the third resistor are connected, a first end of the second resistor is connected to a first DC power supply, a second end of the third resistor is connected to the OTA download recognition signal receiving end of the processor, and the emitter of the first triode is grounded.

2. The program burning circuit according to claim 1, wherein It further includes an external communication recognition circuit; Wherein, the input end of the external communication recognition circuit is connected to a second pin triggered after being connected by an external communication device in the Ethernet interface terminal, and the output end of the external communication recognition circuit is connected to the external communication recognition signal receiving end of the processor; the external communication recognition circuit is used to output different levels when the Ethernet interface terminal is connected to an external communication device and when the Ethernet interface terminal is not connected to the external communication device.

3. The program burning circuit according to claim 2, wherein The external communication recognition circuit specifically includes a fourth resistor, a fifth resistor, and a first capacitor; Wherein, a first end of the fourth resistor is grounded, a second end of the fourth resistor, a first end of the fifth resistor are connected to the second pin, a second end of the fifth resistor, a first end of the first capacitor are connected to the external communication recognition signal receiving end of the processor, and a second end of the first capacitor is grounded.

4. A program burning method based on RS485, characterized in that, Based on a processor, comprising: After the OTA download identification signal receiving end of the processor receives the level representing the OTA download identification signal output by the OTA download identification circuit, an enabling signal is sent through the data sending interface of the processor via the RS485 enabling circuit to activate the receiving enable of the RS485 communicator; Receive the program burning signal of the RS485 data bus through the RS485 communicator; Among them, the OTA download identification signal receiving end of the processor is connected to the output end of the OTA download identification circuit, the input end of the OTA download identification circuit is connected to the first pin triggered after being connected by the OTA download line in the Ethernet interface terminal, the data pins in the Ethernet interface terminal are connected to the slave end data interface of the RS485 communicator, and the host end data interface of the RS485 communicator is correspondingly connected to the data sending interface and the data receiving interface of the processor; The RS485 enabling circuit is an inverter circuit, the input end of the RS485 enabling circuit is connected to the data sending interface of the processor, and the output end of the RS485 enabling circuit is connected to the receiving enable end of the RS485 communicator; The OTA download identification circuit is used to output different levels when the OTA download line is connected to the Ethernet interface terminal and when the OTA download line is not connected to the Ethernet interface terminal; The OTA download identification circuit specifically includes a first resistor, a second resistor, a third resistor and a first triode; Among them, the first end of the first resistor is connected to the first pin, the second end of the first resistor is connected to the base of the first triode, the collector of the first triode, the second end of the second resistor and the first end of the third resistor are connected, the first end of the second resistor is connected to the first DC power supply, the second end of the third resistor is connected to the OTA download identification signal receiving end of the processor, and the emitter of the first triode is grounded.

5. The program burning method according to claim 4, characterized in that It also includes: When the external communication identification signal receiving end of the processor receives the level output by the external communication identification circuit representing that the Ethernet interface terminal is connected to an external communication device, control the RS485 communicator to enter the external communication mode; Among them, the input end of the external communication identification circuit is connected to the second pin triggered after being connected by the external communication device in the Ethernet interface terminal, and the output end of the external communication identification circuit is connected to the external communication identification signal receiving end of the processor; the external communication identification circuit is used to output different levels when the Ethernet interface terminal is connected to the external communication device and when the Ethernet interface terminal is not connected to the external communication device.

6. The program burning method according to claim 5, characterized in that, The external communication identification circuit specifically includes a fourth resistor, a fifth resistor and a first capacitor; Among them, the first end of the fourth resistor is grounded, the second end of the fourth resistor, the first end of the fifth resistor are connected to the second pin, the second end of the fifth resistor, the first end of the first capacitor are connected to the external communication identification signal receiving end of the processor, and the second end of the first capacitor is grounded.

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