Signal processing circuit

Abstract

The utility model relates to a signal processing circuit which comprises a plurality of input signal processing circuits which are connected in parallel. The input signal processing circuit comprises a first voltage dividing module, a rectification module, an electrostatic protection module, a first filtering module, a second voltage dividing module and an optocoupler isolation module. The first voltage dividing module is used for carrying out voltage dividing and / or current limiting processing on an input voltage signal; the rectification module is used for carrying out rectification processing on the voltage signal after voltage division and / or current limiting processing; the electrostatic protection module is used for performing electrostatic protection on the voltage signal output by the rectification module; the first filtering module is used for filtering the voltage signal output by the rectification module; the second voltage dividing module is used for carrying out voltage dividing processing on the filtered voltage signal; the optical coupler isolation module is used for converting the voltage signal subjected to secondary voltage division into a level signal; the output end of the optical coupler isolation module is connected with the signal input interface of the micro-control unit. The scheme can be compatible with direct current input and alternating current input; and power supplies with different voltages are compatible.

Description

Technical Field

[0001] The utility model relates to the technical field of signal processing, and particularly relates to a signal processing circuit. Background Art

[0002] DIDO (Digital In, Digital Out; digital input, digital output), that is, input / output interface technology, is generally used for data, information exchange and control between external devices or user circuits and the CPU; generally speaking, DI input is used to send the switch state signal or digital signal of the external controlled object to the computer or microprocessor; DO output is used to send the digital signal or switch signal sent by the computer to the switch device. In related control schemes, DO output can be controlled through DI input. For example, when using a DIDO module to control DC voltage input, generally a single voltage input is adopted, that is, when facing multiple different input voltages, multiple DIDO modules need to be configured. As a result, when facing multiple different voltages during the production process, the management and control are complex.

[0003] It should be noted that the information disclosed in the above background art section is only used to strengthen the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] The utility model provides a signal processing circuit, which can be compatible with the input of different voltages and effectively overcome the defects existing in the prior art.

[0005] Other features and advantages of the present utility model will become apparent through the following detailed description, or will be partially learned through the practice of the present disclosure.

[0006] According to a first aspect of the present utility model, there is provided a signal processing circuit, including a plurality of input signal processing circuits connected in parallel; the input signal processing circuit includes: a first voltage dividing module, a rectifying module, an electrostatic protection module, a first filtering module, a second voltage dividing module, and an optocoupler isolation module; wherein,

[0007] The input end of the first voltage dividing module is connected to the positive pole of the signal input end, and is used for performing voltage division and / or current limiting processing on the input voltage signal;

[0008] The second input end of the rectifying module is connected to the output end of the voltage dividing module, and is used for rectifying the voltage signal after voltage division and / or current limiting processing; the first input end of the rectifying module is connected to the negative pole of the signal input end;

[0009] The electrostatic protection module is connected to the output end of the rectifying module, and is used for performing electrostatic protection on the voltage signal output by the rectifying module;

[0010] The first filtering module is connected to the output end of the rectifying module and is used for filtering the voltage signal output by the rectifying module;

[0011] The second voltage dividing module is connected to the output end of the rectifying module and is used for dividing the voltage signal after filtering;

[0012] The optocoupler isolation module is connected to the second voltage dividing module and is used for converting the voltage signal after further voltage division into a level signal; the output end of the optocoupler isolation module is connected to the signal input interface of the micro control unit;

[0013] Wherein, the electrostatic protection module, the first filtering module, and the second voltage dividing module are connected in parallel between the output end of the rectifying module and the input end of the optocoupler isolation module.

[0014] In some exemplary embodiments, the input signal processing circuit further includes:

[0015] A matching module, connected to the output end of the optocoupler isolation module, and is used for performing anti-interference processing on the level signal output by the optocoupler isolation module.

[0016] In some exemplary embodiments, the matching module includes a matching resistor R6; the first end of the matching resistor R6 is connected to the output end of the optocoupler isolation module, and the second end of the matching resistor R6 is connected to the signal input interface of the micro control unit.

[0017] In some exemplary embodiments, the voltage dividing module includes a first resistor R1 and a second resistor R2 connected in series, and the first resistor R1 is connected to the positive pole of the signal input end; the second resistor is connected to the second input end of the rectifying module.

[0018] In some exemplary embodiments, the rectifying module includes a rectifier bridge D20; the first input end of the rectifier bridge is connected to the output end of the voltage dividing module; the first input end of the rectifier bridge is connected to the negative pole of the signal input end.

[0019] In some exemplary embodiments, the electrostatic protection module includes an ESD device D10; the ESD device D10 is connected in parallel between the positive output end and the negative output end of the rectifying module.

[0020] In some exemplary embodiments, the optocoupler isolation circuit includes an optocoupler U1, a current limiting resistor R5, a fourth resistor R4, a second filter capacitor C2, and an inverter U2;

[0021] The input end of the optocoupler U1 is connected to the output end of the rectification module, and the first output end of the optocoupler U1 is connected to the ground end; the second output end of the optocoupler U1 is connected to the first end of the current-limiting resistor R5 and the first end of the fourth resistor R4; the second end of the current-limiting resistor R5 is connected to the power supply end; the second end of the fourth resistor R4 is connected to the first end of the second filter capacitor C2 and the input end of the inverter U2; the second end of the second filter capacitor C2 is connected to the ground end; the output end of the inverter U2 is connected in series with the matching module and then connected to the signal input interface of the micro-control unit.

[0022] In some exemplary embodiments, the micro-control unit is connected with a temperature detection circuit for detecting the on-board temperature corresponding to the PCB board, and when the on-board temperature belongs to the first temperature range, reading the level signal output by the input signal processing circuit through the signal input interface; or, when the on-board temperature belongs to the second temperature range, reading the pulse input signal output by the input signal processing circuit through the signal input interface.

[0023] In some exemplary embodiments, the signal processing circuit includes four input signal processing circuits connected in parallel;

[0024] Among them, the second input ends of the rectification modules in each of the input signal processing circuits are respectively connected to the positive poles of the signal input ends; the first input ends of the rectification modules in each of the input signal processing circuits are connected to each other and connected to the negative pole of the signal input end.

[0025] In some exemplary embodiments, the signal output port of the micro-control unit is connected with a signal output circuit provided with an anti-interference circuit.

[0026] The signal processing circuit provided by the embodiment of the present utility model can rectify the input alternating current into an available direct current voltage by setting multiple input signal processing circuits connected in parallel and arranging rectification modules and first filter modules in each signal processing circuit, so that the signal processing circuit can be compatible with both direct current input and alternating current input. And, by configuring the specific values of the resistors and capacitors in the first voltage division module, the second voltage division module and the optocoupler isolation module, different values of power supplies can be compatible. When facing different types of power supplies, it is not necessary to switch different DIDO modules. In addition, by setting an electrostatic protection module, effective electrostatic protection of the voltage signal can be achieved, thereby improving the stability of the signal processing circuit.

[0027] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Brief Description of the Drawings

[0028] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 Schematic diagram showing the module composition of an input signal processing circuit in an exemplary embodiment of the present utility model;

[0030] Figure 2 Schematic circuit diagram showing an input signal processing circuit in an exemplary embodiment of the present utility model;

[0031] Figure 3 Schematic circuit diagram showing a DI module in an exemplary embodiment of the present utility model;

[0032] Figure 4 Schematic circuit diagram showing some pins of the MCU in an exemplary embodiment of the present utility model;

[0033] Figure 5 Schematic diagram showing a signal output circuit in an exemplary embodiment of the present utility model;

[0034] Figure 6 Schematic diagram showing the voltage waveforms before and after rectification in an exemplary embodiment of the present utility model. Detailed implementation manners

[0035] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments.

[0036] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted.

[0037] Exemplary embodiments of the present utility model will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully communicated to those skilled in the art. It should be understood that in the disclosure of the present utility model, the orientation or positional relationship indicated by terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention. Unless otherwise clearly defined and limited, terms such as "installation", "connection", "coupling", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly defined. Those of ordinary skill in the art should be able to understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0038] In view of the disadvantages and deficiencies of the prior art, in this exemplary embodiment, a signal processing circuit is provided, which can be used for a DIDO module. The signal processing circuit may include a plurality of input signal processing circuits connected in parallel. Refer to Figure 1 As shown, for each input signal processing circuit, it may include: a first voltage dividing module 11, a rectifying module 12, an electrostatic protection module 13, a first filtering module 14, a second voltage dividing module 15, and an opto-isolation module 16, which are connected in sequence.

[0039] Among them, in the input signal processing circuit, the input end of the first voltage dividing module 11 is connected to the positive pole of the signal input end, and is used for dividing the voltage of the input voltage signal and / or limiting the current; and inputting the voltage signal after voltage division and / or current limiting to the rectifying module 12. Among them, the signal input end can input a DC voltage or an AC voltage. For example, the input can be an AC 110V voltage, or an AC 220V voltage, or a DC 220V voltage.

[0040] The second input terminal of the rectification module 12 is connected to the output terminal of the voltage division module 11, and is used to perform rectification processing on the voltage signal after voltage division and / or current limiting processing; the first input terminal of the rectification module 11 is connected to the negative pole of the signal input terminal. Among them, when the input is a DC signal, the DC voltage signal remains unchanged; if the input is an AC signal, the rectification module can rectify the AC signal. Refer to Figure 6 As shown, the input AC sine wave is rectified into a DC voltage available for the load.

[0041] At the back end of the rectification module 12, an electrostatic protection module 13, a first filtering module 14, and a second voltage division module 15 are connected in parallel between the output terminal of the rectification module 12 and the input terminal of the optocoupler isolation module 16. The DC voltage signal input by the rectification module 12 first undergoes electrostatic protection through the electrostatic protection module 13; then undergoes filtering processing through the first filtering module 14 to filter out clutter; the filtered voltage signal passes through the second voltage division module 15 for further voltage division processing to further reduce the voltage entering the optocoupler isolation module 16. The first voltage division module and the second voltage division module are respectively arranged on both sides of the rectification module to achieve multi-stage voltage division, effectively suppressing group pulses and surges, avoiding breakdown of the rectification module, and avoiding damage to the optocoupler.

[0042] The optocoupler isolation module 16 is connected to the second voltage division module 15, and the voltage signal after further voltage division is input to the optocoupler isolation module and converted into a level signal; the output terminal of the optocoupler isolation module is connected to the signal input interface of the microcontroller unit, and the level signal is output to the microcontroller unit MCU (Microcontroller Unit). Among them, the MCU can be a single-chip microcomputer.

[0043] Exemplarily, the voltage division module may include a first resistor R1 and a second resistor R2 connected in series. The first resistor R1 is connected to the positive pole of the signal input terminal; the second resistor R2 is connected to the second input terminal of the rectification module.

[0044] Among them, the rectification module can be a rectifier bridge D20. The first input terminal of the rectifier bridge is connected to the second resistor R2 in the voltage division module; the first input terminal of the rectifier bridge D20 is connected to the negative pole of the signal input terminal.

[0045] Exemplarily, the electrostatic protection module can be an ESD device D10; the first filtering module can be a first filtering capacitor C1; the second voltage division module can be a second voltage division resistor R3. Refer to Figure 2 As shown, the ESD device D10, the first filtering capacitor C1, and the second voltage division resistor R3 are connected in parallel at the output terminal of the rectifier bridge.

[0046] Exemplarily, the optocoupler isolation circuit includes: optocoupler U1, current-limiting resistor R5, fourth resistor R4, second filter capacitor C2, and inverter U2. The input end of the optocoupler U1 is connected to the output end of the rectification module, and the first output end of the optocoupler U1 is connected to the ground terminal; the second output end of the optocoupler U1 is connected to the first end of the current-limiting resistor R5 and the first end of the fourth resistor R4; the second end of the current-limiting resistor R5 is connected to the power supply terminal; the second end of the fourth resistor R4 is connected to the first end of the second filter capacitor C2 and the input end of the inverter U2; the second end of the second filter capacitor C2 is connected to the ground terminal; the output end of the inverter U2 is connected in series with the matching module and then connected to the signal input interface of the microcontroller unit.

[0047] Among them, the optocoupler U1 may include a light-emitting diode and a triode, and is electrically isolated between the input end and the output end through an optical signal; it can convert the input electrical signal into an optical signal and then convert the optical signal back into an electrical signal for output. The optocoupler U1 can adopt the optocoupler TLP290. Among them, the triode in the optocoupler U1 can be an NPN-type triode, and the emitter is connected to the ground terminal GND; the collector is connected in series with the current-limiting resistor R5 and then connected to the 5V power supply terminal; in addition, the collector is connected in series with the fourth resistor R4 and then connected in series with the inverter U2. A test point TP1 can also be set between the collector of the triode and the current-limiting resistor R5. In addition, a second filter capacitor C2 is also connected between the fourth resistor R4 and the input end of the inverter U2; the first end of the second filter capacitor C2 is connected to one end of the fourth resistor R4 and the input end of the inverter U2, and the first end of the second filter capacitor C2 is connected to the ground terminal GND. A second detection point TP2 can also be set at the output end of the inverter U2. Among them, the inverter U2 can adopt the inverter SN74LVC14A.

[0048] Exemplarily, the input signal processing circuit further includes: a matching module, connected to the output end of the optocoupler isolation module, for performing anti-interference processing on the level signal output by the optocoupler isolation module.

[0049] Exemplarily, the matching module includes: a matching resistor R6; the first end of the matching resistor R6 is connected to the output end of the optocoupler isolation module, and the second end of the matching resistor R6 is connected to the signal input interface of the microcontroller unit.

[0050] Among them, referring to Figure 2 As shown, a matching resistor R6 can also be connected in series at the output end of the inverter U2, and the second detection point TP2 can be set at the rear end of the matching resistor R6. The level signal output by the inverter, after being divided in voltage and / or limited in current through the matching resistor R6 to achieve anti-interference, is output to the PTA interface of the MCU.

[0051] In some exemplary embodiments, the signal processing circuit includes four input signal processing circuits connected in parallel; wherein, the second input terminals of the rectification modules in each of the input signal processing circuits are respectively connected to the positive pole of the signal input terminal; the first input terminals of the rectification modules in each of the input signal processing circuits are interconnected and connected to the negative pole of the signal input terminal.

[0052] Specifically, referring to Figure 3 As shown, the signal processing circuit includes four input signal processing circuits connected in parallel: DI0, DI1, DI2, and DI3. Among them, the DI-P0 terminal is the positive input terminal of the DI0 circuit; the DI-P1 terminal is the positive input terminal of the DI1 circuit; the DI-P2 terminal is the positive input terminal of the DI2 circuit; the DI-P3 terminal is the positive input terminal of the DI3 circuit. DI-N is the negative input terminal of each circuit and is connected to the negative pole of the signal input terminal.

[0053] In the DI0 circuit, the series-connected resistors R221 and R222 form the first voltage division module. The divided AC voltage signal is input to the rectifier bridge D200, and the rectified DC voltage signal is output; the ESD device D100 performs anti-static protection on the voltage signal output by the rectifier bridge D200; the capacitor C212 serves as the first filter capacitor to filter the DC voltage signal and remove the clutter; the resistor R205 serves as the second voltage division module to further divide the DC voltage signal. The divided signal is input to the opto-isolation circuit; the opto-isolation circuit includes the opto-coupler U105 and the directioner U104F; wherein, the resistor R200 serves as the fifth current-limiting resistor; the resistor R204 serves as the fourth resistor; the capacitor C200 serves as the second filter capacitor. The resistor R203 serves as the matching resistor. The detection points TP140 and TP126 are set as the first detection point and the second detection point respectively. The DI0 input terminal is connected to the 27th pin (PTA13 pin) of the MCU.

[0054] In the DI1 circuit, the series-connected resistors R219 and R220 form the first voltage division module. The divided AC voltage signal is input to the rectifier bridge D201, and the rectified DC voltage signal is output; the ESD device D101 performs anti-static protection on the voltage signal output by the rectifier bridge D201; the capacitor C213 serves as the first filter capacitor to filter the DC voltage signal and remove the clutter; the resistor R210 serves as the second voltage division module to further divide the DC voltage signal. The divided signal is input to the opto-isolation circuit; the opto-isolation circuit includes the opto-coupler U106 and the inverter U104A; wherein, the resistor R206 serves as the fifth current-limiting resistor; the resistor R209 serves as the fourth resistor; the capacitor C203 serves as the second filter capacitor. The resistor R208 serves as the matching resistor. The detection points TP141 and TP127 are set as the first detection point and the second detection point respectively. The DI1 output terminal is connected to the 26th pin (PTA12 pin) of the MCU.

[0055] In the DI1 circuit, the series-connected resistors R219 and R220 form the first voltage division module. The divided AC voltage signal is input to the rectifier bridge D201, and the rectified DC voltage signal is output; the ESD device D101 performs anti-static protection on the voltage signal output by the rectifier bridge D201; the capacitor C213 acts as the first filter capacitor to filter the DC voltage signal and filter out the clutter; the resistor R210 acts as the second voltage division module to divide the DC voltage signal again. The divided signal is input to the opto-isolation circuit; the opto-isolation circuit includes the optocoupler U106 and the inverter U104A; among them, the resistor R206 acts as the fifth current-limiting resistor; the resistor R209 acts as the fourth resistor; the capacitor C203 acts as the second filter capacitor. The resistor R208 acts as the matching resistor. The detection points TP141 and TP127 are set as the first detection point and the second detection point respectively. The output end of DI1 is connected to the 26th pin (PTA12 pin) of the MCU.

[0056] In the DI2 circuit, the series-connected resistors R207 and R223 form the first voltage division module. The divided AC voltage signal is input to the rectifier bridge D206, and the rectified DC voltage signal is output; the ESD device D102 performs anti-static protection on the voltage signal output by the rectifier bridge D206; the capacitor C215 acts as the first filter capacitor to filter the DC voltage signal and filter out the clutter; the resistor R226 acts as the second voltage division module to divide the DC voltage signal again. The divided signal is input to the opto-isolation circuit; the opto-isolation circuit includes the optocoupler U107 and the inverter U104B; among them, the resistor R202 acts as the fifth current-limiting resistor; the resistor R225 acts as the fourth resistor; the capacitor C214 acts as the second filter capacitor. The resistor R224 acts as the matching resistor. The detection points TP138 and TP134 are set as the first detection point and the second detection point respectively. The output end of DI2 is connected to the 23rd pin (PTB3 / SCL pin) of the MCU.

[0057] In the DI3 circuit, the series resistors R228 and R229 form the first voltage division module. The divided AC voltage signal is input to the rectifier bridge D207, and the rectified DC voltage signal is output; the ESD device D103 provides electrostatic protection for the voltage signal output by the rectifier bridge D207; the capacitor C217 acts as the first filter capacitor to filter the DC voltage signal and remove the clutter; the resistor R232 acts as the second voltage division module to divide the DC voltage signal again. The divided signal is input to the opto-isolation circuit; the opto-isolation circuit includes the optocoupler U108 and the inverter U104C; among them, the resistor R227 acts as the fifth current-limiting resistor; the resistor R231 acts as the fourth resistor; the capacitor C216 acts as the second filter capacitor. The resistor R230 acts as the matching resistor. The detection points TP139 and TP135 are set as the first detection point and the second detection point respectively. The output end of DI3 is connected to the 24th pin (PTB4 / SDA pin) of the MCU.

[0058] For example, in each input signal processing circuit, a rectifier can be used to rectify the AC sine wave input into a DC voltage available to the load. The rectified voltage is output as high and low levels through an optocoupler and an inverter. When the input is an AC voltage, one of high level, low level, and pulse square wave can be output through the opto-isolation circuit. By adjusting the resistance values of the resistors in the first voltage division module, the second voltage division module, and the current-limiting resistor, as well as the capacitance value of the second filter capacitor, the DI input can be made compatible with 110V and 220V DI inputs.

[0059] Among them, taking the DI0 circuit as an example, the specific calculation formulas for the corresponding resistor and capacitor values can include: Among them, CTR is the current transfer ratio of the optocoupler, and IC and IF can be calculated through the following formulas respectively:

[0060] Among them, Vin is the voltage between the DI_P0 terminal and the DI_N terminal; Vd200 is the voltage of two series-connected diodes of the rectifier bridge, which is 1.4V in the normal state; the value of V is 5V; Vu105 is the operating voltage of the primary light-emitting diode of the optocoupler, and the normal value is 1.1 - 1.4V. VCE(sat) is the voltage after the optocoupler enters the saturation state, and the voltage range is 0.2 - 0.3V.

[0061] For example, taking the DI0 circuit as an example, the resistance values of the resistors R221 and R222 can be 110kΩ, the capacitor C212 is 1μF, the resistor R205 can be 6.8kΩ, the resistor R200 can be 30kΩ, the resistor R204 can be 10kΩ, and the capacitor C200 can be 470nF.

[0062] At room temperature, when VIN is an AC input, the voltage across the optocoupler is a positive half-sine wave, and a pulse waveform will appear at the detection point TP140. When the second filter capacitor C200 is 10 nF, pulse waveforms are output when VIN < 240V. When the second filter capacitor C200 is 100 nF, a high level is output at the detection point TP126 when VIN > 100V; when the second filter capacitor C200 is adjusted to 470 nF, if <VIN> 60V, the detection point TP140 outputs a low level and the detection point TP126 outputs a high level. The microcontroller reads the high level and controls the DO output.

[0063] In some exemplary embodiments, the microcontroller unit is connected to a temperature detection circuit for detecting the on-board temperature corresponding to the PCB board, and when the on-board temperature belongs to a first temperature range, reading the level signal output by the input signal processing circuit through the signal input interface; or, when the on-board temperature belongs to a second temperature range, reading the pulse input signal output by the input signal processing circuit through the signal input interface.

[0064] Specifically, referring to Figure 4 as shown, it can be that the 17th pin of the MCU is connected to the temperature detection circuit. The 17th pin of the MCU is respectively connected to the first end of the resistor R130 and the first end of the resistor RT1. The second end of the resistor R130 is connected to the 3V power supply terminal; the second end of the resistor RT1 is connected to the ground terminal.

[0065] The DI input of the DIDO module outputs a high-level signal to the microcontroller through the optocoupler and the inverter to control the triode to drive the relay to conduct, thereby controlling the DO output. Considering that the CTR of the optocoupler will have different performances at high and low temperatures, the CTR of the optocoupler will be lower at low temperatures, and only a lower IF is required to make the microcontroller receive a high level; while at high temperatures, on the contrary, a higher conduction voltage is required to make the microcontroller receive a high level. Considering this factor, it is necessary to ensure that DI input > 79V and a high level is output; DI input < 40V and a low level is output. Due to the characteristics of the optocoupler, it is difficult to debug a reasonable value to meet this condition. Therefore, we add a temperature detection circuit to detect the on-board temperature of the PCB at the ADC port of the MCU. When NTC < 60°C, the DI input port of the MCU still reads high and low levels. When NTC > 70°C, the DI input port of the MCU is changed to read the pulse input. When the input duty cycle > 70%, it is determined that the DI input is valid and the DO output is controlled. If only high and low levels are read, when the ambient temperature is 70°C, DI input > 90V for the microcontroller to receive a high-level signal. Adding the NTC detection circuit and the pulse input detection can enable the microcontroller to meet the requirements in both high and low temperature states, with DI > 79V to control the DO output and DI < 40V for the MCU to not act.

[0066] Exemplarily, a signal output circuit provided with an anti-interference circuit is connected to the signal output port of the micro control unit.

[0067] Specifically, for the 28th pin, 29th pin, 20th pin, and 19th pin of the MCU, as DO ports, they are respectively connected to the signal output circuit, and the signal output circuits connected to each DO port are the same. Refer to Figure 5 As shown, taking the DO2 port as an example, the signal output circuit includes: resistor R15, inverter U109A, anti-interference circuit, inverter U109F, resistor R126, transistor Q202, diode D204, capacitor C207, and relay K202. Among them, the anti-interference circuit may include: resistor R9, resistor R13, resistor R5, capacitor C3, diode D5, and diode D6.

[0068] One end of resistor R15 is connected to the DO2 port of the MCU and the inverter U109A, and the other end is connected to the ground terminal GND. The output end of inverter U109A is connected to the first end of resistor R9 of the anti-interference circuit, and the second end of resistor R9 is connected to the first end of resistor R13, the positive electrode of diode D5, and the negative electrode of diode D6; the second end of resistor R13 is connected to the positive electrode of diode D6, the first end of capacitor C3, the first end of resistor R5, and is connected to inverter U109F; the negative electrode of diode D5 is connected to the second end of capacitor C3, the second end of resistor R5, and the 3V power supply terminal. The anti-interference circuit is arranged between the output end of inverter U109A and the input end of inverter U109F. The output end of inverter U109F is respectively connected to the first end of resistor R126 and the first end of transistor Q202; the second end of resistor R126 is connected to the ground terminal; the second end of transistor Q202 is connected to the ground terminal; the third end of transistor Q202 is connected to the positive electrode of diode D204, the first end of capacitor C207, and relay K202; the negative electrode of diode D204 is connected to the 5V power supply terminal; the second end of capacitor C207 is connected to the ground terminal GND; the power supply terminal of relay K202 is connected to the 5V power supply terminal. Among them, transistor Q202 can be a logic level enhanced field effect transistor, such as a BSS123 type transistor. By adding an anti-interference circuit to the DO output circuit, the stability and accuracy of the output signal are improved.

[0069] The signal processing circuit of the present utility model can be a DIDO circuit including 4 parallel input signal processing circuits. By setting a rectifier bridge and using the adjustment of multi-stage voltage dividing resistors, users can use the DIDO module more conveniently. It is not necessary to replace the DIDO module when switching between 110V and 220V system power supplies, nor is it necessary to pay attention to whether the input is AC or DC.

[0070] Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known or customary technical means in the art not disclosed herein. The specification and examples are only to be considered exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims.

[0071] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A signal processing circuit, characterized in that, The signal processing circuit includes a plurality of input signal processing circuits connected in parallel; the input signal processing circuit includes: a first voltage dividing module, a rectifying module, an electrostatic protection module, a first filtering module, a second voltage dividing module, and an optocoupler isolation module; wherein, The input end of the first voltage dividing module is connected to the positive pole of the signal input end, and is used for performing voltage division and / or current limiting processing on the input voltage signal; The second input end of the rectifying module is connected to the output end of the voltage dividing module, and is used for rectifying the voltage signal after voltage division and / or current limiting processing; the first input end of the rectifying module is connected to the negative pole of the signal input end; The electrostatic protection module is connected to the output end of the rectifying module, and is used for performing electrostatic protection on the voltage signal output by the rectifying module; The first filtering module is connected to the output end of the rectifying module, and is used for filtering the voltage signal output by the rectifying module; The second voltage dividing module is connected to the output end of the rectifying module, and is used for performing voltage division on the filtered voltage signal; The optocoupler isolation module is connected to the second voltage dividing module, and is used for converting the voltage signal after voltage division again into a level signal; the output end of the optocoupler isolation module is connected to the signal input interface of the micro control unit; Wherein, the electrostatic protection module, the first filtering module, and the second voltage dividing module are connected in parallel between the output end of the rectifying module and the input end of the optocoupler isolation module.

2. The signal processing circuit according to claim 1, wherein The input signal processing circuit further includes: A matching module, connected to the output end of the optocoupler isolation module, and is used for performing anti-interference processing on the level signal output by the optocoupler isolation module.

3. The signal processing circuit according to claim 2, wherein The matching module includes: a matching resistor R6; the first end of the matching resistor R6 is connected to the output end of the optocoupler isolation module, and the second end of the matching resistor R6 is connected to the signal input interface of the micro control unit.

4. The signal processing circuit according to claim 1, characterized in that, The voltage dividing module includes a first resistor R1 and a second resistor R2 connected in series, and the first resistor R1 is connected to the positive pole of the signal input end; the second resistor R2 is connected to the second input end of the rectifying module.

5. The signal processing circuit according to claim 1, wherein The rectifying module includes a rectifier bridge D20; the first input end of the rectifier bridge D20 is connected to the output end of the voltage dividing module; the first input end of the rectifier bridge D20 is connected to the negative pole of the signal input end.

6. The signal processing circuit according to claim 1, wherein The electrostatic protection module includes: an ESD device D10; the ESD device D10 is connected in parallel between the positive output end and the negative output end of the rectifying module.

7. The signal processing circuit according to claim 1, characterized in that, The optocoupler isolation circuit includes: an optocoupler U1, a current limiting resistor R5, a fourth resistor R4, a second filter capacitor C2, and an inverter U2; The input end of the optocoupler U1 is connected to the output end of the rectification module, and the first output end of the optocoupler U1 is connected to the ground end; the second output end of the optocoupler U1 is connected to the first end of the current-limiting resistor R5 and the first end of the fourth resistor R4; the second end of the current-limiting resistor R5 is connected to the power supply end; the second end of the fourth resistor R4 is connected to the first end of the second filter capacitor C2 and the input end of the inverter U2; the second end of the second filter capacitor C2 is connected to the ground end; the output end of the inverter U2 is connected to the signal input interface of the micro-control unit after being connected in series with the matching module.

8. The signal processing circuit according to claim 1, wherein The micro-control unit is connected with a temperature detection circuit, which is used for detecting the on-board temperature corresponding to the PCB board, and when the on-board temperature belongs to the first temperature range, reading the level signal output by the input signal processing circuit through the signal input interface; Or, when the on-board temperature belongs to the second temperature range, reading the pulse input signal output by the input signal processing circuit through the signal input interface.

9. The signal processing circuit according to claim 1, wherein The signal processing circuit includes four input signal processing circuits connected in parallel; Among them, the second input ends of the rectification modules in each input signal processing circuit are respectively connected to the positive pole of the signal input end; the first input ends of the rectification modules in each input signal processing circuit are communicated with each other and connected to the negative pole of the signal input end.

10. The signal processing circuit according to claim 1, wherein The signal output port of the micro-control unit is connected to a signal output circuit provided with an anti-interference circuit.

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