Three-state switch signal acquisition circuit and method

Abstract

The invention provides a three-state switch signal acquisition circuit. The three-state switch signal acquisition circuit comprises an IN port, an OUT port, a switch S1, a switch S2, a first power supply, a second power supply, a first resistor, a second resistor, a third resistor and a capacitor C1. One end of the IN port is connected with one end of the switch S1 and one end of the switch S2, the other end of the switch S1 is connected with the first power supply, and the other end of the switch S2 is grounded. According to the three-state switch signal acquisition circuit provided by the embodiment of the invention, the problem of hardware resource redundancy caused by poor expansibility of the MCU due to the fact that an existing automobile ECU switch interface circuit can only fixedlyidentify low effective signals and high effective signals is solved. The three states of high-side signal input, suspension and low-side signal input can be simply and accurately recognized, and theproblem that different switch states are difficult to recognize due to the fact that threshold design of the three states of suspension, low connection and high connection is unreasonable is solved.

Description

technical field [0001] The embodiment of the present invention relates to the field of automobile ECU switch signal acquisition, in particular to a three-state switch signal acquisition circuit and method. Background technique [0002] The digital switch signal acquisition circuit is an important part of the automotive ECU hardware. Its design form is closely related to the extended performance of the port, and the high and low side attributes of the switching signals that need to be processed by the functional circuit widely used in the ECU hardware are different. For the acquisition of switch signals in different states of the ECU, the first method is to design the acquisition of high-side switch signals as a default pull-down circuit, and design the acquisition of low-side switch signals as a default pull-up circuit. These two types of circuits only It can fixedly identify the high effective signal and the low effective signal respectively, and cannot identify the high-si...

AI Technical Summary

Problems solved by technology

However, this interface design is both pull-up and pull-down. If other ECUs are connected to the switch acquisition circuit at the same time, the voltage division coefficient of the circuit itself will be affected, causing the circuit itself to fail to work. The switch interface circuit of the ECU cannot work

And even if this design is not affected by other interface access, the sampling values ​​of different switch states are different under different voltages, and it cannot be guaranteed that in a wide enough voltage range, the sampling values ​​of the three switching states are different. The difference is large enough to distinguish, and the method of using software lookup table will be very complicated

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