System and method for self-adaptive identification of piano key action

Abstract

The invention discloses a system and method for self-adaptive identification of piano key action. The system mainly comprises a key detection unit and a main control unit. The method comprises the steps of 1, applying for an array BOT [7]; 2, initializing peripheral equipment; 3, scanning the ADC value once; 4, gradually switching on all LEDs and then switching off the LEDs to show that equipment is ready, and to prevent the situation that the IO state of the equipment is unstable during starting to make the LEDs switched on by accident; 5, making the equipment enter the working state; 6, scanning the ADC value of seven white keys circularly; and 7, sending a key press-down signal through UART if the ADC value is larger than the rising threshold VH[i], sending a key lifting signal if the ADC value is smaller than the descending threshold VL[i], and returning to step 5 for the next round of scanning. A hysteresis comparative method is adopted, one third and two thirds of the difference value of output voltage of a phototube reflected by a lifted key and a pressed key are used as comparative values, false triggering is effectively avoided, accuracy is high, stability and reliability are realized, and using is convenient.

Description

technical field [0001] The invention relates to the field of music education assistance. Background technique [0002] With the continuous improvement of people's living standards, piano education has become popular in more and more families, and many auxiliary products for piano education have appeared on the market. Almost all piano educational aids need to prompt the user to press a key and detect whether the note produced by the key action is the correct note. [0003] There are many methods of button action detection, such as using a pickup to collect audio and then analyzing the audio frequency to identify notes. It is more accurate to identify single tones, but the accuracy rate is low when identifying polyphonic sounds; using mechanical switch type touch buttons, when the button is pressed, it drives The switch action is used to detect the button action, which is stable and reliable, but it is extremely inconvenient to use the height of the switch and the device to ...

AI Technical Summary

Problems solved by technology

[0003] There are many methods of button action detection, such as using a pickup to collect audio and then analyzing the audio frequency to identify notes. It is more accurate to identify single tones, but the accuracy rate is low when identifying polyphonic sounds; using mechanical switch type touch buttons, when the button is pressed, it drives The switch action is used to detect the button action, which is stable and reliable, but it is extremely inconvenient to use the height of the switch and the device to be adjusted; a photoelectric switch can also be used to detect the distance between the button and the switch, and the output voltage of the photoelectric switch changes when the button is pressed. The action of the key is detected by identifying the change of the voltage, but every time the device is placed on the key, the distance between the switch and the key is different, and the different lighting conditions make the initial value of the output voltage of the photoelectric switch different every time, so that It is difficult to set the threshold of the switching voltage, causing false triggering of the device, making the accuracy of note recognition very low

[0004] Their shortcomings are: due to external influences, such as power frequency interference, high-power radio frequency interference, etc., the output voltage of the reflected photoelectric cell will be superimposed with a certain noise voltage, so that the trigger will be reached many times during the key pressing or lifting process. Conditions, resulting in multiple lift-up or press-down signals by mistake, affecting normal use

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