Current output type AK protocol wheel speed sensor receiving circuit

Abstract

The utility model discloses a current output type AK protocol wheel speed sensor receiving circuit. The current output type AK protocol wheel speed sensor receiving circuit comprises an identification circuit and a voltage conversion circuit used for converting current signals output by an AK protocol wheel speed sensor into voltage signals. The identification circuit comprises a speed pulse identification circuit used for comparing the voltage signal with a first standard voltage and outputting a first square wave signal represented by a high level and a low level. The data bit identification circuit is used for comparing the voltage signal with a second standard voltage and a third standard voltage at the same time and outputting a second square wave signal represented by a high level and a low level, and the speed pulse identification circuit and the data bit identification circuit are both connected with the voltage conversion circuit; wherein the current signal is divided into a high level, a middle level and a low level according to the magnitude of the current, and the magnitude of the first standard voltage and the magnitude of the third standard voltage are between the voltage signal corresponding to the high level and the voltage signal corresponding to the middle level. The size of the second standard voltage is between the voltage signal corresponding to the middle grade and the voltage signal corresponding to the low grade. According to the utility model, the current signal output by the AK protocol wheel speed sensor can be converted into the square wave signal which can be analyzed by a common chip, and the square wave signal can be analyzed only by a common electric appliance element, so that the use of a foreign special chip is avoided, the cost is reduced, and the convenience is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of automobiles, and particularly relates to a current output type AK protocol wheel speed sensor receiving circuit. Background Art

[0002] The wheel speed sensor is a sensor used to measure the rotation speed of the car wheels. It is one of the most critical sensors in today's cars. Most of the current wheel speed sensors use the AMR magnetoresistive principle and can accurately output signals such as the air gap size, forward and reverse direction, and wheel speed information through the AK protocol. However, there are currently no ready-made chips in China that can directly communicate with the wheel speed sensor to receive information. Only some dedicated integrated chips abroad integrate the wheel speed sensor receiving module, such as STMicroelectronics' chassis-specific digital-analog hybrid system basic chip L9396. The chip also includes a power management module, a half-bridge, a high-low board driver, a CAN module, a BLDC pre-driver module, an ADC module, etc. However, these dedicated integrated chips are almost all developed and produced abroad, and are rare and expensive. Utility Model Content

[0003] In order to solve the above technical problems, the utility model provides a current output type AK protocol wheel speed sensor receiving circuit, which can convert the current signal output by the AK protocol wheel speed sensor into a square wave signal that can be analyzed by an ordinary chip, and only ordinary electrical components are needed to achieve it, avoiding the use of foreign dedicated chips, reducing costs and improving convenience.

[0004] The technical solution adopted by the utility model is: a current output type AK protocol wheel speed sensor receiving circuit, including an identification circuit and a voltage conversion circuit for converting a current signal output by the AK protocol wheel speed sensor into a voltage signal;

[0005] The identification circuit includes a speed pulse identification circuit for comparing the voltage signal with a first standard voltage and outputting a first square wave signal represented by a high and low level, and a data bit identification circuit for comparing the voltage signal with a second standard voltage and a third standard voltage at the same time and outputting a second square wave signal represented by a high and low level, and the speed pulse identification circuit and the data bit identification circuit are both connected to the voltage conversion circuit;

[0006] The current signal is divided into high, medium and low levels according to the magnitude of the current. The magnitudes of the first standard voltage and the third standard voltage are both between the voltage signal corresponding to the high level and the voltage signal corresponding to the medium level. The magnitude of the second standard voltage is between the voltage signal corresponding to the medium level and the voltage signal corresponding to the low level.

[0007] A further improvement of the current output type AK protocol wheel speed sensor receiving circuit of the utility model is that the voltage conversion circuit includes a first resistor and a voltage amplifier circuit, the output end of the AK protocol wheel speed sensor is respectively connected to one end of the first resistor and the input end of the voltage amplifier circuit, the other end of the first resistor is grounded, and the output end of the voltage amplifier circuit outputs the voltage signal and is connected to the identification circuit.

[0008] A further improvement of the current output type AK protocol wheel speed sensor receiving circuit of the utility model is that the voltage amplification circuit includes an operational amplifier, a second resistor and a third resistor, the output end of the AK protocol wheel speed sensor is connected to the non-inverting input end of the operational amplifier, one end of the second resistor is connected to the inverting input end of the operational amplifier, the other end of the second resistor is grounded, and the two ends of the third resistor are respectively connected to the inverting input end and the output end of the operational amplifier.

[0009] A further improvement of the current output type AK protocol wheel speed sensor receiving circuit of the utility model is that the resistance values ​​of the second resistor and the third resistor are adjustable.

[0010] A further improvement of the current output type AK protocol wheel speed sensor receiving circuit of the utility model is that the speed pulse identification circuit is a voltage comparator, the first standard voltage is provided by a first power supply and connected to the second input end of the voltage comparator, and the voltage conversion circuit outputs the voltage signal and is connected to the first input end of the voltage comparator.

[0011] A further improvement of the current output type AK protocol wheel speed sensor receiving circuit of the utility model is that the data bit recognition circuit is a window comparator, the second standard voltage is provided by the second power supply and connected to the second input end of the window comparator, the third standard voltage is provided by the third power supply and connected to the third input end of the window comparator, and the voltage conversion circuit outputs the voltage signal and is connected to the first input end of the window comparator.

[0012] The utility model can convert the current signal output by the AK protocol wheel speed sensor into two different voltage square wave signals, which is convenient for ordinary chips to perform data analysis and can detect abnormal conditions of the signal harness. Moreover, the utility model only needs ordinary electrical components to achieve this, avoiding the use of foreign dedicated chips, reducing costs and improving convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a circuit principle diagram of an embodiment of the utility model.

[0015] Figure 2 It is the voltage square wave equivalent diagram corresponding to the output current signal of the AK protocol wheel speed sensor.

[0016] Figure 3 This is a waveform diagram of a first square wave signal outputted by an embodiment of the present utility model.

[0017] Figure 4 This is a waveform diagram of a second square wave signal outputted by an embodiment of the present utility model. DETAILED DESCRIPTION

[0018] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0019] Since there is no existing chip that can directly communicate with the AK protocol wheel speed sensor to receive information, and the dedicated integrated chip that integrates the wheel speed sensor receiving module is rare and expensive. Therefore, the utility model provides a current output type AK protocol wheel speed sensor receiving circuit, which can convert the current signal output by the AK protocol wheel speed sensor into a square wave signal that can be analyzed by an ordinary chip, and only ordinary electrical components are needed to achieve it, avoiding the use of foreign dedicated chips, reducing costs and improving convenience.

[0020] The current output type AK protocol wheel speed sensor receiving circuit of the utility model is described in detail below with reference to the accompanying drawings and embodiments.

[0021] See also Figure 1As shown, a current output type AK protocol wheel speed sensor receiving circuit includes an identification circuit II and a voltage conversion circuit I for converting a current signal I0 output by the AK protocol wheel speed sensor into a voltage signal V0; the identification circuit II includes a speed pulse identification circuit 21 for comparing the voltage signal V0 with a first standard voltage V1 and outputting a first square wave signal represented by a high and low level, and a data bit identification circuit 22 for comparing the voltage signal V0 with a second standard voltage V2 and a third standard voltage V3 at the same time and outputting a second square wave signal represented by a high and low level, and the speed pulse identification circuit 21 and the data bit identification circuit 22 are both connected to the voltage conversion circuit I. Since the current output type AK protocol wheel speed sensor transmits data by changing the current size, the current signal I0 outputted by it is divided into three levels of high, medium and low according to the current size, wherein the high level current is generally 24mA for speed pulses, the medium level current is generally 14mA for data protocol bits, and the low level current is generally 7mA for the low level of the signal. In order to receive and identify the high, medium and low levels of the current signal, the receiving circuit of this embodiment sets the magnitude of the first standard voltage V1 and the third standard voltage V3 to be between the voltage signal corresponding to the high level and the voltage signal corresponding to the medium level, and sets the magnitude of the second standard voltage V2 to be between the voltage signal corresponding to the medium level and the voltage signal corresponding to the low level. By identifying the high, medium and low levels of the current signal I0, the speed pulse information AK_SPEED (i.e., the first square wave signal) and the data protocol bit information AK_DATA (i.e., the second square wave signal) can be identified, and the two square wave signals can be connected to the IO pins of the chip MCU for data analysis, and the abnormal state of the AK protocol wheel speed sensor can be detected according to the state of these two convenient signals, such as detecting whether the signal harness is short-circuited to the power supply, short-circuited to the ground or open-circuited, etc.

[0022] As a preferred embodiment, in order to increase the discrimination of the voltages corresponding to the three levels of current signals, and facilitate the subsequent identification circuit II to identify. In addition to the first resistor R1 for converting the current signal into the corresponding voltage signal, the voltage conversion circuit I also includes a voltage amplifier circuit, which further includes an operational amplifier 11 (such as LM2904 of T1 Company), a second resistor R2 and a third resistor R3. The output end of the AK protocol wheel speed sensor is respectively connected to one end of the first resistor R1 and the in-phase input terminal IN1+ of the operational amplifier 11, the other end of the first resistor R1 is grounded, one end of the second resistor R2 is connected to the inverting input terminal IN1- of the operational amplifier 11, the other end of the second resistor R2 is grounded, and the two ends of the third resistor R3 are respectively connected to the reverse input terminal IN1- and the output end of the operational amplifier 11. The operational amplifier 11 amplifies the initially converted voltage signal and outputs the amplified voltage signal V0 at the output end, and the speed pulse identification circuit 21 and the data bit identification circuit 22 of the subsequent identification circuit II are both connected to the amplified voltage signal V0 for identification. Preferably, the resistance values ​​of the second resistor R2 and the third resistor R3 are adjustable, and R2 and R3 are adaptively adjusted to ensure that the three levels of voltage signals corresponding to the high, medium and low level current signals can satisfy the requirements of the first standard voltage V1, the second standard voltage V2 and the third standard voltage V3, thereby ensuring effective recognition of the identification circuit II.

[0023] As a preferred embodiment, the speed pulse identification circuit 21 is a voltage comparator (such as LM2901PT of ST Company), the first standard voltage V1 is connected to the second input terminal IN12 of the voltage comparator, the voltage conversion circuit I outputs the voltage signal V0 and is connected to the first input terminal IN11 of the voltage comparator, and the voltage comparator outputs the first square wave signal from the output terminal OUT1 after comparison. The data bit identification circuit 22 is a window comparator (such as also built by LM2901PT of ST Company), the second standard voltage V2 is connected to the second input terminal IN22 of the window comparator, the third standard voltage V3 is connected to the third input terminal IN23 of the window comparator, the voltage conversion circuit I outputs the voltage signal V0 and is connected to the first input terminal IN21 of the window comparator, and the window comparator outputs the second square wave signal from the output terminal OUT2 after comparison. Among them, the first standard voltage V1, the second standard voltage V2 and the third standard voltage V3 can all be realized by using a 5V power supply and different voltage-dividing resistor combinations.

[0024] Below Figure 1 The receiving circuit shown is used as an example to illustrate the recognition principle:

[0025] Cooperate Figure 2 to Figure 4As shown, first, the current signal I0 output by the current output type AK protocol wheel speed sensor is connected to the first resistor R1, which will generate an initial voltage signal corresponding to the magnitude of the current signal I0, and the initial voltage signal is amplified to the voltage amplifier circuit to provide discrimination. The voltage signal V0 obtained after amplification is simultaneously connected to the voltage comparator 21 and the window comparator 22.

[0026] The function of the voltage comparator 21 satisfies: when the voltage of the input IN11 is greater than the reference voltage of the input IN12, OUT1 outputs a high level; when the voltage of the input IN11 is less than the reference voltage of the input IN12, OUT1 outputs a low level. Therefore, when V0>V1, the voltage comparator outputs a high level, otherwise it outputs a low level.

[0027] The function of the window comparator 22 satisfies: when the voltage of the input IN21 is greater than the reference voltage of the input IN22 and less than the reference voltage of the input IN23, OUT2 outputs a high level; in other cases, OUT2 outputs a low level. Therefore, when V2<V0<V3, the window comparator 22 outputs a high level, and in other cases, it outputs a low level.

[0028] Since the AK protocol wheel speed sensor transmits data by changing the current size, based on the high, medium and low level classification of the current signal, the size of the voltage signal V0 is also divided into high, medium, low and high levels. The current signal I0 output by the AK protocol wheel speed sensor can be equivalent to a voltage square wave equivalent diagram, such as Figure 2 As shown: When the current signal I0 is high, V0 = V H ; When the current signal I0 is at a medium level, V0 = V M ; When the current signal I0 is low level, V0=V L . The voltage-dividing resistor at the first power supply is changed to adjust the magnitude of the first standard voltage V1 so that V M <V1<V H , then when the AK protocol wheel speed sensor outputs a high-level current signal, the output terminal OUT1 of the voltage comparator 21 outputs a high level, and in other cases it outputs a low level. After receiving the current signal I0 for a period of time, the signal output by the voltage comparator 21 will be characterized as a first square wave signal, such as Figure 3 As shown. By changing the voltage divider resistors at the second power supply and the third power supply to adjust the second standard voltage V2 and the third standard voltage V3, V L <V2<V M <V3<V H, then when the AK protocol wheel speed sensor outputs a medium-level current signal, the output terminal OUT2 of the window comparator 22 outputs a high level, and in other cases it outputs a low level. After receiving the current signal I0 for a period of time, the signal output by the window comparator 22 will be characterized as a second square wave signal, such as Figure 4 shown.

[0029] The above receiving circuit receives the current signal I0 and identifies its high, medium and low levels, and then obtains the speed pulse information AK_SPEED and the data protocol bit information AK_DATA. Then, these two pieces of information are connected to the IO pins of the chip MCU for data analysis. The abnormal state of the AK protocol wheel speed sensor can also be detected according to the state of these two convenient signals, such as whether the signal harness is short-circuited to the power supply, short-circuited to the ground or open-circuited. The electrical components used in the entire circuit are relatively common, and the functions are easy to implement, avoiding the use of foreign dedicated chips and reducing costs.

[0030] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of the present specification are only used to match the contents disclosed in the specification for people familiar with the technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present utility model, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the present utility model, should still fall within the scope of the technical contents disclosed by the present utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in the present specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present utility model. The change or adjustment of the relative relationship, without substantial change of the technical contents, should also be regarded as the scope of the implementation of the present utility model.

[0031] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A current output type AK protocol wheel speed sensor receiving circuit, characterized in that: It includes an identification circuit and a voltage conversion circuit for converting a current signal output by an AK protocol wheel speed sensor into a voltage signal; The identification circuit includes a speed pulse identification circuit for comparing the voltage signal with a first standard voltage and outputting a first square wave signal represented by a high and low level, and a data bit identification circuit for comparing the voltage signal with a second standard voltage and a third standard voltage at the same time and outputting a second square wave signal represented by a high and low level, and the speed pulse identification circuit and the data bit identification circuit are both connected to the voltage conversion circuit; The current signal is divided into high, medium and low levels according to the magnitude of the current. The magnitudes of the first standard voltage and the third standard voltage are both between the voltage signal corresponding to the high level and the voltage signal corresponding to the medium level. The magnitude of the second standard voltage is between the voltage signal corresponding to the medium level and the voltage signal corresponding to the low level.

2. The current output type AK protocol wheel speed sensor receiving circuit as claimed in claim 1, characterized in that: The voltage conversion circuit includes a first resistor and a voltage amplifier circuit. The output end of the AK protocol wheel speed sensor is respectively connected to one end of the first resistor and the input end of the voltage amplifier circuit. The other end of the first resistor is grounded. The output end of the voltage amplifier circuit outputs the voltage signal and is connected to the identification circuit.

3. The current output type AK protocol wheel speed sensor receiving circuit as claimed in claim 2, characterized in that: The voltage amplification circuit includes an operational amplifier, a second resistor and a third resistor. The output end of the AK protocol wheel speed sensor is connected to the non-inverting input end of the operational amplifier, one end of the second resistor is connected to the inverting input end of the operational amplifier, the other end of the second resistor is grounded, and the two ends of the third resistor are respectively connected to the inverting input end and the output end of the operational amplifier.

4. The current output type AK protocol wheel speed sensor receiving circuit as claimed in claim 3, characterized in that: The resistance values ​​of the second resistor and the third resistor are adjustable.

5. The current output type AK protocol wheel speed sensor receiving circuit as claimed in claim 1, characterized in that: The speed pulse identification circuit is a voltage comparator, the first standard voltage is provided by a first power supply and connected to the second input terminal of the voltage comparator, and the voltage conversion circuit outputs the voltage signal and connected to the first input terminal of the voltage comparator.

6. The current output type AK protocol wheel speed sensor receiving circuit as claimed in claim 5, characterized in that: The data bit identification circuit is a window comparator, the second standard voltage is provided by a second power supply and connected to the second input terminal of the window comparator, the third standard voltage is provided by a third power supply and connected to the third input terminal of the window comparator, and the voltage conversion circuit outputs the voltage signal and is connected to the first input terminal of the window comparator.

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