Electronic accordion and control system thereof

Abstract

The invention discloses an electronic accordion and a control system thereof, the control system comprises a key plate scanning circuit, the key plate scanning circuit comprises a first main control unit, a key matrix unit, a first row scanning unit and a first column scanning unit, wherein the first column scanning unit comprises at least one parallel input and serial output first shift register, parallel input pins of the first shift register are correspondingly and electrically connected with each column line of the key matrix unit, and the first shift register is used for collecting first electric contact pressing level signals of each column line in parallel; a clock pin of the first shift register is connected to the first main control unit to receive a clock signal CLK sent by the first main control unit, and a serial output pin of the first shift register is connected to the first main control unit to convert a first electric contact pressing level signal acquired in parallel into a serial signal and output the serial signal to the first main control unit; in this way, occupation of I / O pins of the main control unit can be remarkably reduced, and hardware resources are saved.

Description

Technical Field

[0001] This invention relates to the field of electronic music equipment technology, and more specifically, to an electronic accordion and its control system. Background Technology

[0002] Keyboard instruments such as electronic accordions, accordions, and pipe organs are widely used in music performance and teaching. With technological advancements, electronic keyboard instruments (such as electronic accordions) have gradually emerged, replacing traditional physical resonance with electroacoustic amplification to achieve timbre expansion, volume control, and functional integration. Real-time key status detection is a core technology in electronic keyboard instruments, directly impacting performance response speed and user experience. Currently, the mainstream key scanning method is matrix scanning. This method arranges the keys in a row-column matrix and uses the I / O pins of a microcontroller (MCU) to drive the row lines and detect the column lines, achieving rapid identification of key press / release states. However, the traditional matrix scanning method suffers from significant I / O resource consumption: for an M-row, N-column key matrix, it requires M output pins (row drive) and N input pins (column detection), totaling (M+N) I / O ports. As the number of keys increases (such as 61-key or 88-key keyboards), the number of required I / O pins increases linearly, leading to a shortage of microcontroller resources. This limits the system's ability to integrate other functions (such as sound processing, communication interfaces, display control, etc.) and restricts the miniaturization design of electronic keyboard instruments. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electronic accordion and its control system, which can reduce the number of I / O pins required by the microcontroller and is conducive to the miniaturization of the electronic accordion.

[0004] This invention provides a control system for an electronic accordion, including a keypad scanning circuit, wherein the keypad scanning circuit includes; First main control unit; The piano key matrix unit includes a plurality of first electrical contacts, which are arranged in a row-column alternating manner; The first row scanning unit, controlled by the first main control unit, is configured to cyclically output the first row scanning signal to each row line of the piano key matrix unit; The first column scanning unit includes at least one first shift register with parallel input and serial output. The parallel input pin of the first shift register is electrically connected to each column line of the key matrix unit to acquire the first electrical contact pressing level signal of each column line in parallel. The clock pin of the first shift register is connected to the first master control unit to receive the clock signal CLK issued by the first master control unit. The serial output pin of the first shift register is connected to the first master control unit to convert the parallel acquired first electrical contact pressing level signal into a serial signal and output it to the first master control unit.

[0005] Furthermore, the first electrical contacts of the key matrix unit are arranged in an 8-row-11-column staggered pattern; The first row scanning unit includes an interface P1, a first pull-up resistor R3, and a second pull-up resistor R4. The first pull-up resistor R3 and the second pull-up resistor R4 are respectively connected to the eight row lines IN1-IN8 of the key matrix unit. Pin 1 of the interface P1 is connected to the input voltage, and pins 2-9 of the interface P1 are respectively connected to the eight row lines IN1-IN8 of the key matrix unit. Pins 2-9 of the interface P1 are also connected to the first master control unit to receive the row drive signal sent by the first master control unit. Pin 10 of the interface P1 is connected to the first master control unit, and pin 11 of the interface P1 is connected to the first master control unit to send the serial signal DATA to the first master control unit.

[0006] Furthermore, there are two first shift registers, namely shift register U2 and shift register U3; The Q0-Q7 pins of the shift register U2 are respectively connected to 8 column lines OUT1-OUT8 of the key matrix unit to collect the first electrical contact press level signal. The A and B pins of the shift register U2 are connected to pin 11 of interface P1. The CLK pin of the shift register U2 is connected to pin 10 of interface P1. The VCC pin of the shift register U2 is connected to the operating voltage through resistor R2. The Q0-Q2 pins of the shift register U3 are respectively connected to the remaining 3 column lines OUT9-OUT11 of the key matrix unit to collect the first electrical contact press level signal. The A and B pins of the shift register U3 are connected to the Q7 pin of the shift register U2. The CLK pin of the shift register U3 is connected to the 10 pin of the interface P1. The VCC pin of the shift register U2 is connected to the operating voltage through the resistor R1.

[0007] Furthermore, it also includes a function panel scanning circuit, the function panel scanning circuit comprising: Second main control unit; The function key matrix unit includes a plurality of second electrical contacts, which are arranged in a row-column alternating manner; The second row scanning unit, controlled by the second main control unit, is configured to cyclically output the second row scanning signal to each row line of the function key matrix unit; The second column scanning unit includes at least one second shift register with parallel input and serial output. The parallel input pin of the second shift register is electrically connected to each column line of the function key matrix unit to acquire the second electrical contact press level signal of each column line in parallel. The clock pin of the second shift register is connected to the second main control unit to receive the clock signal CLK issued by the second main control unit. The serial output pin of the second shift register is connected to the second main control unit to convert the parallel acquired second electrical contact press level signal into a serial signal and output it to the second main control unit.

[0008] Furthermore, it also includes a chord plate scanning circuit, the chord plate scanning circuit comprising: The chord key matrix unit includes a plurality of third electrical contacts, which are arranged in a row-column alternating manner; The third main control unit is configured to cyclically output the third row scan signal to each row of the chord key matrix unit, and to acquire the third electrical contact press level signal of each column of the chord key matrix unit in parallel.

[0009] Furthermore, the chord plate scanning circuit also includes an interface circuit 1 for connecting the third main control unit and the pitch bend board, an interface circuit 2 for connecting the third main control unit and the left and right octave pitch bend boards, an interface circuit 3 for connecting the third main control unit and the LCD panel, and an interface circuit 4 for connecting the third main control unit and the function board.

[0010] Furthermore, it also includes a power management module; the power management module includes a low-dropout linear regulator, used to convert the input voltage of the external power supply 5V into the operating voltage 3.3V, to power the first main control unit, the second main control unit, the third main control unit, the first shift register and the second shift register.

[0011] Furthermore, the power management module includes a chip U1 and capacitors C3-C6. The VIN pin of the chip U1 is used to connect to the input voltage of 5V, and the VOUT pin of the chip U1 is used to output the operating voltage of 3.3V. Capacitors C3 and C4 are connected in parallel between the VOUT pin of the chip U1 and ground, and capacitors C5 and C6 are connected in parallel between the VIN pin of the chip U1 and ground.

[0012] Furthermore, both the first shift register and the second shift register are 74HC165 chips.

[0013] This invention also provides an electronic accordion, including keys and a control system for the electronic accordion described above.

[0014] Beneficial Effects: The electronic accordion control system provided in this embodiment includes a keypad scanning circuit. The keypad scanning circuit includes a first main control unit, a key matrix unit, a first row scanning unit, and a first column scanning unit. The key matrix unit includes a plurality of first electrical contacts arranged in a row-column alternating manner. The first row scanning unit is controlled by the first main control unit and configured to cyclically output first row scanning signals to each row line of the key matrix unit. The first column scanning unit includes at least one first shift register with parallel input and serial output. The parallel input pin of the first shift register is electrically connected to each column line of the key matrix unit for parallel acquisition of the first electrical contact press level signals of each column line. The clock pin of the first shift register is connected to the first main control unit to receive the clock signal CLK emitted by the first main control unit. The serial output pin of the first shift register is connected to the first main control unit to convert the parallel acquired first electrical contact press level signals into serial signals and output them to the first main control unit. Therefore, by using a shift register with parallel input and serial output for data acquisition, the matrix keypad / The multi-level acquisition requirements of the contacts are integrated into the transmission of a small number of serial communication pins, which significantly reduces the I / O pin occupation of the main control unit. This not only saves hardware resources and reduces the pin count dependence of the main control unit selection, but also reserves more I / O expansion space for the main control unit, improving the integration and functional expandability of the circuit. Attached Figure Description

[0015] The technical solution and its beneficial effects of the present invention will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the keypad scanning circuit according to an embodiment of the present invention; Figure 2 This is a circuit diagram of the piano key matrix unit according to an embodiment of the present invention; Figure 3 This is a circuit schematic diagram of the first row scanning unit in an embodiment of the present invention; Figure 4 This is a circuit schematic diagram of the first column scanning unit in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the functional panel scanning circuit according to an embodiment of the present invention; Figure 6 This is a circuit schematic diagram of the function key matrix unit according to an embodiment of the present invention; Figure 7 This is a circuit schematic diagram of the second row scanning unit according to an embodiment of the present invention; Figure 8 This is a circuit schematic diagram of the second column scanning unit in an embodiment of the present invention; Figure 9 This is a schematic diagram of the chord plate scanning circuit according to an embodiment of the present invention; Figure 10 This is a circuit schematic diagram of the chord key matrix unit according to an embodiment of the present invention; Figure 11 This is a circuit schematic diagram of the third main control unit provided in an embodiment of the present invention; Figure 12 These are circuit schematics of interface circuit two and interface circuit three provided in embodiments of the present invention; Figure 13 These are the circuit diagrams of interface circuit one, interface circuit four, and interface circuit five provided in the embodiments of the present invention. Detailed Implementation

[0017] Please refer to the diagrams, where the same component symbols represent the same components. The principles of the invention are illustrated by way of example implemented in a suitable computing environment. The following description is based on the illustrative specific embodiments of the invention and should not be construed as limiting the invention to other specific embodiments not detailed herein.

[0018] refer to Figure 1 This invention provides a control system for an electronic accordion, including a keypad scanning circuit 10. The keypad of the electronic accordion is the core input module that carries pitch triggering, and multi-key recognition is achieved based on a matrix circuit. The keypad scanning circuit 10 includes a first main control unit 101, a key matrix unit 102, a first row scanning unit 103, and a first column scanning unit 104.

[0019] The piano key matrix unit 102 includes several first electrical contacts arranged in a row-column alternating manner. These contacts are essentially switch structures, corresponding to the piano keys. One key can correspond to one electrical contact, or it can correspond to two independent electrical contacts. When a key is configured to correspond to one electrical contact, pressing the key triggers the closure of that contact. When a key is configured to correspond to two independent electrical contacts, these two contacts are triggered sequentially during key pressing. Typically, one contact closes first, and the other closes when the key is pressed further.

[0020] In some embodiments, a plurality of first electrical contacts of the key matrix unit 102 are arranged in an 8-row-11-column staggered pattern, such as Figure 2 The first electrical contacts are electrical contacts SW1~SW73, the key matrix unit 102 has 8 row lines and 11 column lines, and the components Q1~Q37 are transistors or triodes.

[0021] The first row scanning unit 103 is controlled by the first main control unit 101 and is configured to cyclically output the first row scanning signal to each row line of the key matrix unit 102. Further, as... Figure 3 As shown, the first row scanning unit 103 includes interface P1, interface P2, a first pull-up resistor R3, and a second pull-up resistor R4. Each of the first pull-up resistor R3 and the second pull-up resistor R4 includes four pull-up resistors connected in parallel, thus the eight parallel pull-up resistors are connected to eight row lines IN1-IN8 respectively. Pin 1 of interface P1 is connected to an input voltage of 5V. Pins 2-9 of interface P1 are connected to the eight row lines IN1-IN8 of the key matrix unit 102, respectively. Pins 2-9 of interface P1 are also connected to the first master control unit 101 to receive row drive signals sent by the first master control unit. Pin 10 of interface P1 is connected to the first master control unit 101 to output the clock signal CLK of the first master control unit 101. Pin 11 of interface P1 is connected to the first master control unit 101 to send the serial signal DATA to the first master control unit 101. Pin 1 of interface P2 is connected to column line OUT11 of key matrix unit 102, pin 2 is connected to electrical contact SW29 of key matrix unit 102, and pin 3 is connected to electrical contact SW38 of key matrix unit 102.

[0022] The first column scanning unit 104 includes at least one first shift register with parallel input and serial output. The parallel input pin of the first shift register is electrically connected to each column line of the key matrix unit 102 to acquire the first electrical contact pressing level signal of each column line in parallel. The clock pin of the first shift register is connected to the first master control unit 101 to receive the clock signal CLK issued by the first master control unit 101. The serial output pin of the first shift register is connected to the first master control unit 101 to convert the parallel acquired first electrical contact pressing level signal into a serial signal and output it to the first master control unit 101.

[0023] In some implementations, such as Figure 4 As shown, there are two first shift registers, namely shift register U2 and shift register U3. The Q0-Q7 pins of shift register U2 are parallel input pins, which are connected to eight column lines OUT1-OUT8 of the key matrix unit 101 to collect the first electrical contact press level signal. The A and B pins of shift register U2 are serial output pins, which are connected to pin 11 of interface P1. The CLK pin of shift register U2 is connected to pin 10 of interface P1. The VCC pin of shift register U2 is connected to the operating voltage of 3.3V through resistor R2. The Q0-Q2 pins of shift register U3 are connected to the remaining three column lines OUT9-OUT11 of the key matrix unit to respectively acquire the first electrical contact press level signal. The A and B pins of shift register U3 are connected to the Q7 pin of shift register U2. The CLK pin of shift register U3 is connected to the 10 pin of interface P1. The VCC pin of shift register U2 is connected to the operating voltage of 3.3V through resistor R1.

[0024] The CLK pins of shift registers U2 and U3 receive the clock signal CLK from the first master control unit 101 through pin 10 of interface P1. The serial signal DATA of shift register U2 is sent to the first master control unit 101 through pin 11 of interface P1. The serial signal of shift register U3 is sent to shift register U2 through its A and B pins, and then sent to the first master control unit 101 through the A and B pins of shift register U2.

[0025] In an embodiment of the present invention, the scanning process of the keyboard scanning circuit 10 is as follows: the first main control unit 101 outputs the first row scanning signal (e.g., sequentially lowering the level of a certain row line) to the eight row lines IN1-IN8 of the keyboard matrix unit 102 through pins 2-9 of interface P1. When a certain row line is selected (e.g., IN1 is lowered), if the corresponding keyboard key is pressed, the corresponding first electrical contact (e.g., SW1) will close, causing the level of the corresponding column line (e.g., OUT1) to be lowered; if the keyboard key is configured with dual electrical contacts, the two electrical contacts will be triggered sequentially during the pressing process (one closes first, and the other closes when pressed deeper), and the level of the corresponding column line will change twice. The shift register U2 (parallel input pins Q0-Q7) collects the level signals of the eight column lines OUT1-OUT8, and the shift register U3 (parallel input pins Q0-Q2) collects the level signals of the remaining three column lines OUT9-OUT11, synchronously acquiring the electrical contact status of all columns in the current row. Shift registers U2 and U3 receive the clock signal CLK sent by the first master control unit 101 through interface pins P1-10, converting the parallel-acquired column level signals into serial signals. The serial signal from shift register U3 is first transmitted to shift register U2, and finally, U2 sends the cascaded serial signal DATA to the first master control unit 101 through interface pins P1-11. The above steps are repeated cyclically across all row lines, sequentially scanning row lines IN2-IN8 to complete the status acquisition of all first electrical contacts (SW1-SW73) in 8 rows × 11 columns. Finally, the first master control unit 101 analyzes and determines the pressed key.

[0026] Therefore, the keyboard scanning circuit 10 of this embodiment of the invention, by using a shift register with parallel input and serial output for data acquisition, can integrate the multi-column level acquisition requirements of matrix keys / contacts into the transmission of a small number of serial communication pins, significantly reducing the I / O pin occupation of the main control unit. This not only saves hardware resources and reduces the pin number dependence of the main control unit selection, but also reserves more I / O expansion space for the main control unit, improving the integration and functional expandability of the circuit.

[0027] See Figure 5 In this embodiment of the invention, the control system of the electronic accordion also includes a function panel scanning circuit 20. The function panel mainly integrates auxiliary modules of various control buttons / knobs, which are responsible for mode switching and parameter adjustment.

[0028] The function panel scanning circuit 20 includes a second main control unit 201, a function key matrix unit 202, a second row scanning unit 203, and a second column scanning unit 204. Among them, for example... Figure 6 As shown, the function key matrix unit 202 includes several second electrical contacts, namely electrical contacts S1-S2, electrical contacts S9-S12, electrical contacts S19-S22, ..., electrical contacts S67-S70. These second electrical contacts are arranged in a row-column interleaved manner, including 6 row lines D0-D5 and 10 column lines K2, K4-K12.

[0029] The second row scanning unit 203 is controlled by the second main control unit 201 and is configured to cyclically output the second row scanning signal to each row line D0-D5 of the function key matrix unit 202. For example... Figure 7 As shown, the second row scanning unit 203 includes an interface J1, a third pull-up resistor R7, a fourth pull-up resistor R8, and a chip U11. The third pull-up resistor R7 and the fourth pull-up resistor R8 each include four pull-up resistors connected in parallel. The specific circuit connection of each component can be found in the circuit diagram shown in the figure.

[0030] The second column scanning unit 204 includes at least one second shift register with parallel input and serial output. The parallel input pin of the second shift register is electrically connected to each column line K2, K4-K12 of the function key matrix unit 202, for parallel acquisition of the second electrical contact press level signals of each column line. The clock pin of the second shift register is connected to the second main control unit 201 to receive the clock signal CLK issued by the second main control unit 201. The serial output pin of the second shift register is connected to the second main control unit 201 to convert the parallel acquired second electrical contact press level signals into serial signals and output them to the second main control unit 201. Figure 8As shown, the second shift register includes shift register U13 and shift register U14. The connection relationship between shift register U13 and shift register U14 and each column line can be referred to the circuit diagram shown in the figure.

[0031] In this embodiment of the invention, the scanning process of the function panel scanning circuit 20 is as follows: the second main control unit 201 controls the second row scanning unit 203 to cyclically output the second row scanning signal to the row lines D0-D5 of the function key matrix unit 202 (for example, sequentially pulling down the level of a certain row line). When a certain row line is selected (e.g., D0 is pulled low), if the second electrical contact (e.g., S1, S2, etc.) connected to that row line in the function key matrix unit 202 is pressed, the level of the corresponding column line (e.g., K2, K4, etc.) will be pulled low; the shift registers U13 and U14 of the second column scanning unit 204 synchronously acquire the level signals of all column lines (K2, K4-K12) through parallel input pins. The shift registers U13 and U14 receive the clock signal CLK from the second main control unit 201, convert the parallel acquired column level signals into serial signals, and transmit them to the second main control unit 201 through serial output pins. Repeat the above steps to scan all rows in a loop, scanning rows D1-D5 in sequence, to complete the status acquisition of the second electrical contacts (S1-S2, S9-S12, etc.) at all row-column intersections, and finally the second main control unit 201 analyzes the pressed function key.

[0032] See Figure 9 The control system of the electronic accordion in this embodiment of the invention further includes a chord board scanning circuit 30, which includes a third main control unit 301 and a chord key matrix unit 302.

[0033] The chord key matrix unit 302 includes several third electrical contacts, such as Figure 10 As shown, several third electrical contacts, such as contacts W20-W26, W36-W42, W51-W58, W67-74, and W83-W90, are arranged in a row-column alternating manner, including five row lines H2-H5 and ten column lines L1-L10.

[0034] like Figure 11 As shown, the third main control unit 301 can be an STM32 microcontroller in an LQFP48 package, configured to cyclically output the third row scan signal to each row line H2-H5 of the chord key matrix unit 302, and to acquire the third electrical contact press level signal of each column line L-L10 of the chord key matrix unit 302 in parallel.

[0035] like Figure 12 and Figure 13As shown, the chord board scanning circuit 30 also includes an interface circuit P15 for connecting the third main control unit 301 and the pitch bend board, an interface circuit P11 for connecting the third main control unit 301 and the left and right octave pitch bend boards, an interface circuit P12 for connecting the third main control unit 301 and the LCD panel, an interface circuit P13 for connecting the third main control unit 301 and the function board, and an interface circuit P14 for connecting the third main control unit 301 and the Bluetooth module.

[0036] The first main control unit 101 and the second main control unit 201 can also be implemented using an STM32 microcontroller in an LQFP48 package.

[0037] In this embodiment, the working principle of the chord board scanning circuit 30 is as follows: the third main control unit 301 (STM32 microcontroller) cyclically outputs the third row scanning signal to the row lines H2-H5 of the chord key matrix unit 302 (e.g., sequentially lowering the level of a certain row line), selecting the row corresponding to the chord key row by row. When a row line is selected, if the third electrical contact (e.g., W20) corresponding to that row is pressed, the level of the corresponding column line (e.g., L3) will change as the electrical contact closes; the third main control unit 301 collects the level signals of column lines L1-L10 in parallel, and combines them with the currently selected row line to deduce the pressed chord key (corresponding to the specific electrical contact in W20-W90). The third main control unit 301 communicates synchronously with the pitch bend board, octave converter board, LCD panel, function board, and Bluetooth module through corresponding interface circuits (P15 / P11 / P12 / P13 / P14). For example, it receives control signals from the pitch bend board and octave converter board to adjust chord parameters; outputs chord status display information to the LCD panel; interacts with the function board to realize the linkage adjustment of chord modes / parameters; and transmits chord data (such as external device control) through the Bluetooth module.

[0038] In this embodiment of the invention, the control system of the electronic accordion further includes a power management module 40. The power management module 40 includes a low-dropout linear regulator for converting the input voltage of the external power supply (5V) into a working voltage (3.3V) to power the first main control unit, the second main control unit, the third main control unit, the first shift register, and the second shift register. Specifically, the power management module 40 includes a chip U1 and capacitors C3-C6. The VIN pin of the chip U1 is used to connect to the input voltage of 5V, and the VOUT pin of the chip U1 is used to output the working voltage of 3.3V. Capacitors C3 and C4 are connected in parallel between the VOUT pin of the chip U1 and ground, and capacitors C5 and C6 are connected in parallel between the VIN pin of the chip U1 and ground.

[0039] In this embodiment of the invention, both the first shift register and the second shift register are 74HC165 chips.

[0040] This invention also provides an electronic accordion, comprising keys and a control system for the electronic accordion described in the above embodiments.

[0041] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A control system for an electronic accordion, characterized in that The keyboard plate scanning circuit comprises; The first main control unit; The keyboard matrix unit comprises a plurality of first electric contacts arranged in a row-column crossing manner; The first row scanning unit is controlled by the first main control unit and is configured to cyclically output a first row scanning signal to each row line of the keyboard matrix unit; The first column scanning unit comprises at least one first shift register with parallel input and serial output, the parallel input pin of the first shift register is electrically connected to each column line of the keyboard matrix unit, and is used for collecting the pressing level signals of the first electric contacts of each column line in parallel, the clock pin of the first shift register is connected to the first main control unit to receive the clock signal CLK sent by the first main control unit, and the serial output pin of the first shift register is connected to the first main control unit, so as to convert the collected pressing level signals of the first electric contacts into serial signals and output the serial signals to the first main control unit.

2. The control system for an electronic accordion according to claim 1, characterized in that, The plurality of first electric contacts of the keyboard matrix unit are arranged in an 8-row-11-column crossing manner; The first row scanning unit comprises an interface P1, a first pull-up resistor R3 and a second pull-up resistor R4, the first pull-up resistor R3 and the second pull-up resistor R4 are connected to the 8 row lines IN1-IN8 of the keyboard matrix unit respectively, the 1 pin of the interface P1 is connected to an input voltage, the 2-9 pins of the interface P1 are connected to the 8 row lines IN1-IN8 of the keyboard matrix unit respectively, the 2-9 pins of the interface P1 are also connected to the first main control unit to receive the row driving signals sent by the first main control unit respectively, the 10 pin of the interface P1 is connected to the first main control unit, and the 11 pin of the interface P1 is connected to the first main control unit to send the serial signals DATA to the first main control unit.

3. The control system for an electronic accordion according to claim 2, characterized in that, The first shift register has two, which are shift register U2 and shift register U3 respectively; The Q0-Q7 pins of the shift register U2 are connected to the 8 column lines OUT1-OUT8 of the keyboard matrix unit respectively to collect the pressing level signals of the first electric contacts, the A pin and the B pin of the shift register U2 are connected to the 11 pin of the interface P1, the CLK pin of the shift register U2 is connected to the 10 pin of the interface P1, and the VCC pin of the shift register U2 is connected to a working voltage through the resistor R2; The Q0-Q2 pins of the shift register U3 are connected to the remaining 3 column lines OUT9-OUT11 of the keyboard matrix unit respectively to collect the pressing level signals of the first electric contacts, the A pin and the B pin of the shift register U3 are connected to the Q7 pin of the shift register U2, the CLK pin of the shift register U3 is connected to the 10 pin of the interface P1, and the VCC pin of the shift register U2 is connected to a working voltage through the resistor R1.

4. The control system for an electronic accordion according to claim 3, characterized in that, The functional panel scanning circuit comprises: The second main control unit; The functional key matrix unit comprises a plurality of second electric contacts arranged in a row-column crossing manner; The functional key matrix unit comprises a plurality of second electric contacts arranged in a row-column crossing manner; A second row scanning unit controlled by the second master control unit is configured to cyclically output a second row scanning signal to each row line of the functional key matrix unit; The second column scanning unit comprises at least one second shift register with parallel input and serial output. The parallel input pin of the second shift register is electrically connected to each column line of the functional key matrix unit, for parallel collection of the second electrical contact pressing level signals of each column line. The clock pin of the second shift register is connected to the second master control unit to receive the clock signal CLK sent by the second master control unit. The serial output pin of the second shift register is connected to the second master control unit, for conversion of the parallel collected second electrical contact pressing level signals into serial signals and output to the second master control unit.

5. The control system for an electronic accordion according to claim 4, characterized in that, The chord plate scanning circuit further comprises: The chord key matrix unit comprises a plurality of third electrical contacts arranged in a row-column crossing manner. The third master control unit is configured to cyclically output a third row scanning signal to each row line of the chord key matrix unit, and to parallel collect the third electrical contact pressing level signals of each column line of the chord key matrix unit.

6. The control system for an electronic accordion according to claim 5, characterized in that, The chord plate scanning circuit further comprises an interface circuit one for connecting the third master control unit and the fretboard, an interface circuit two for connecting the third master control unit and the left-right octave transposition board, an interface circuit three for connecting the third master control unit and the liquid crystal board, and an interface circuit four for connecting the third master control unit and the functional board.

7. The control system for an electronic accordion of claim 5, wherein, The power management module comprises a low-dropout linear voltage regulator for converting an input voltage 5V of an external power supply into a working voltage 3.3V, to supply power to the first master control unit, the second master control unit, the third master control unit, the first shift register, and the second shift register.

8. The control system for an electronic accordion according to claim 7, characterized in that, The power management module comprises a chip U1 and capacitors C3-C6. The VIN pin of the chip U1 is used to connect the input voltage 5V. The VOUT pin of the chip U1 is used to output the working voltage 3.3V. The capacitor C3 and the capacitor C4 are connected in parallel between the VOUT pin of the chip U1 and the ground. The capacitor C5 and the capacitor C6 are connected in parallel between the VIN pin of the chip U1 and the ground.

9. The control system of claim 4, wherein, The first shift register and the second shift register are both 74HC165 chips.

10. An electronic accordion, characterized by Control system for an electronic piano comprising keys and a control system according to any one of claims 1-9. Control system for an electronic piano comprising keys and a control system according to any one of claims 1-9.

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