CN210167009U

CN210167009U - Practical embedded Linux experimental device

Info

Publication number: CN210167009U
Application number: CN201921064821.6U
Authority: CN
Inventors: 冯迅; 云利军
Original assignee: Yunnan Normal University
Current assignee: Yunnan Normal University
Priority date: 2019-07-09
Filing date: 2019-07-09
Publication date: 2020-03-20
Anticipated expiration: 2029-07-09

Abstract

The utility model provides a practical embedded Linux experimental apparatus, including embedded ARM nuclear core plate, audio input output interface, LCD screen, touch-sensitive screen, rotary encoder, charactron, infrared receiving tube, temperature sensor, photo resistance, AD sampling adjustable resistance, bee calling organ, relay, button, serial EEPROM memory, I/0 extension interface and power. Has the advantages that: the embedded Linux hardware experiment system has the advantages that abundant hardware experiment modules are provided, especially, a nixie tube dynamic scanning and rotary encoder is added, experiment pleasure and learning effects are greatly improved, and the learning practice range of the embedded Linux is expanded. The core board is connected with the embedded ARM core board in a jumper wire mode, so that a learner can conveniently reselect a connecting pin of the CPU, and the wiring flexibility is high. The structure of the nixie tube is designed, the nixie tube with four shared segment code ports realizes dynamic scanning, the cost is saved, and the pin expenditure is reduced.

Description

Practical embedded Linux experimental device

Technical Field

The utility model belongs to the technical field of computer hardware design, concretely relates to practical embedded Linux experimental apparatus.

Background

The Linux technology is a representative technology of an embedded system, and is a skill which must be mastered by professional students such as electronic, instrument and computer. In the Linux teaching, a Linux teaching experimental device is required to be used for teaching, so that students can understand the working principle of the embedded real-time operating system and the using method of the embedded development tool, and the ability of the students to use the embedded real-time operating system is developed.

The existing Linux teaching experiment device mainly has the problem of few types of expanded hardware unit circuits in system hardware design, so that the experiment items are few, and the experiment resources are not rich. In addition, there is a problem that wiring is not flexible in terms of wiring.

SUMMERY OF THE UTILITY MODEL

To the defect that prior art exists, the utility model provides a practical embedded Linux experimental apparatus can effectively solve above-mentioned problem.

The utility model adopts the technical scheme as follows:

the utility model provides a practical embedded Linux experimental device, which comprises an embedded ARM core board, an audio input/output interface, a liquid crystal screen, a touch screen, a rotary encoder, a nixie tube, an infrared receiving tube, a temperature sensor, a photosensitive resistor, an A/D sampling adjustable resistor, a buzzer, a relay, a key, a serial EEPROM memory, an I/0 expansion interface and a power supply;

the audio input and output interface is connected with corresponding pins of the embedded ARM core board;

the pins of the liquid crystal screen and the touch screen are combined together and are connected to one end of an IDE40 interface, and the other end of the IDE40 interface is connected to corresponding pins of the embedded ARM core board;

the rotary encoder adopts a circle of mechanical type with keys and outputs 30 pulses, and is connected to corresponding pins of the embedded ARM core board through pull-up resistors;

the nixie tube adopts 4-bit common-anode type 7-section nixie tubes, adopts a dynamic scanning wiring mode and is connected to corresponding pins of the embedded ARM core board in a jumper wiring mode;

the infrared receiving tube is connected to corresponding pins of the embedded ARM core board in a jumper connection mode;

the temperature sensor adopts a single bus form and is connected to the independent pins of the embedded ARM core board in a jumper connection mode;

the photoresistor is connected with an analog/digital conversion input pin of the embedded ARM core board after being subjected to resistance voltage division;

the A/D sampling adjustable resistor is connected to an analog/digital conversion input pin of the embedded ARM core board in a jumper connection mode;

the buzzer and the relay are connected to corresponding pins of the embedded ARM core board in a jumper connection mode;

the keys are respectively connected with 4 interrupt pins of the embedded ARM core board in a jumper wire connection mode by adopting 4 independent keys;

the serial EEPROM memory is connected to corresponding pins of the embedded ARM core board in a jumper connection mode;

the I/0 expansion interface is connected to corresponding pins of the embedded ARM core board;

the power supply is connected to the power supply pin of the embedded ARM core board after voltage stabilization is carried out through the low-dropout linear voltage stabilization chip.

Preferably, the I/0 expansion interface includes a serial interface, a USB interface, a TF card interface, an RJ45 network interface, an LED interface, and an SPI interface;

the serial port interface, the USB interface, the TF card interface, the RJ45 network interface, the LED interface and the SPI interface are respectively connected to corresponding pins of the embedded ARM core board.

Preferably, the nixie tube has 7 segment code interfaces, the 7 segment code interfaces are connected to the input interface of the first short-circuit jumper unit with seven bits after passing through a respective current-limiting resistor, and the output interface of the first short-circuit jumper unit is connected to the corresponding GPG port of the embedded ARM core board;

the nixie tube has 4 bit code interfaces, each bit code interface is connected to a collector electrode of a corresponding PNP type triode, an emitting electrode of the PNP type triode is connected to a positive power supply end, and a base electrode of the PNP type triode is connected to an input interface of a four-bit second short-circuit jumper unit after passing through a 1K resistor; and four output interfaces of the second short-circuit jumper unit are connected to corresponding GPG ports of the embedded ARM core board.

Preferably, the 1 st encoding output end and the 2 nd encoding output end of the rotary encoder are respectively connected with the positive end of a power supply through pull-up resistors; meanwhile, the 1 st coding output end and the 2 nd coding output end of the rotary coder are respectively connected to an interrupt port of the embedded ARM core board; and the press output end of the rotary encoder is connected to an interrupt port of the embedded ARM core board.

The utility model provides a practical embedded Linux experimental apparatus has following advantage:

(1) the embedded Linux hardware experiment system has the advantages that abundant hardware experiment modules are provided, especially, a nixie tube dynamic scanning and rotary encoder is added, experiment pleasure and learning effects are greatly improved, and the learning practice range of the embedded Linux is expanded. Through the practical application of education institutions, the experimental learning effect is better than that of other existing products.

(2) The main experiment module is connected with the embedded ARM core board in a jumper wire mode, so that a learner can conveniently reselect a connecting pin of the CPU, and the wiring flexibility is high.

(3) The structure of the nixie tube is designed, the nixie tube with four shared segment code ports realizes dynamic scanning, the cost is saved, and the pin expenditure is reduced.

Drawings

Fig. 1 is a circuit diagram of an audio input/output interface provided by the present invention;

fig. 2 is a circuit diagram of an lcd interface provided by the present invention;

fig. 3 is a circuit diagram of a rotary encoder according to the present invention;

fig. 4 is a circuit diagram of the nixie tube provided by the present invention;

fig. 5 is a circuit diagram of the infrared receiving tube and the temperature sensor provided by the present invention;

FIG. 6 is a circuit diagram of the photo resistor and the A/D sampling adjustable resistor provided by the present invention;

fig. 7 is a circuit diagram of a buzzer and a relay provided by the present invention;

fig. 8 is a circuit diagram of the key provided by the present invention;

fig. 9 is a circuit diagram of a power supply provided by the present invention;

fig. 10 is a circuit diagram of a serial port interface provided by the present invention;

fig. 11 is a circuit diagram of a USB interface provided by the present invention;

fig. 12 is a circuit diagram of a TF card interface provided by the present invention;

fig. 13 is a circuit diagram of an RJ45 network interface provided by the present invention;

fig. 14 is a circuit diagram of an LED interface and an SPI interface provided by the present invention;

fig. 15 is a circuit diagram of a serial EEPROM provided by the present invention.

Detailed Description

In order to make the technical problem, technical solution and advantageous effects solved by the present invention more clearly understood, the following description is given in conjunction with the accompanying drawings and embodiments to further explain the present invention in detail. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

The utility model provides a practical embedded Linux experimental apparatus is applied to computer technology education and teaching trade, provides abundant hardware experiment resource, the strong advantage of wiring flexibility, can provide high-efficient, convenient experiment platform for the learner of learning embedded Linux system.

Specifically, the practical embedded Linux experimental device comprises an embedded ARM core board, an audio input/output interface, a liquid crystal screen, a touch screen, a rotary encoder, a nixie tube, an infrared receiving tube, a temperature sensor, a photosensitive resistor, an A/D sampling adjustable resistor, a buzzer, a relay, a key, a serial EEPROM memory, an I/0 expansion interface and a power supply.

(1) Embedded ARM core board

The embedded ARM core board uses the latest S3C2416 type embedded CPU.

In order to simplify wiring, the embedded ARM core board and the external sensor are connected in a jumper wire mode, so that a learner can conveniently reselect a connecting pin of a CPU, the experimental range is greatly expanded, and the wiring flexibility is high.

(2) The pins of the liquid crystal screen and the touch screen are combined together and are connected to one end of a small IDE40 interface, and the other end of the IDE40 interface is connected to corresponding pins of the embedded ARM core board; referring to fig. 2, a circuit diagram of the lcd interface is shown.

(3) The rotary encoder adopts a circle of mechanical type with keys and outputs 30 pulses, and is connected to corresponding pins of the embedded ARM core board through pull-up resistors.

Specifically, the 1 st encoding output end and the 2 nd encoding output end of the rotary encoder are respectively connected with the positive end of a power supply through pull-up resistors; meanwhile, the 1 st coding output end and the 2 nd coding output end of the rotary coder are respectively connected to an interrupt port of the embedded ARM core board; and the press output end of the rotary encoder is connected to an interrupt port of the embedded ARM core board.

Referring to fig. 3, a circuit diagram of a rotary encoder is shown. The rotary encoder is a mechanical device, and two pulse signals having a constant accompanying difference are generated at two output pins during rotation. The phase difference of the two pulse signals determines the direction of rotation (i.e. clockwise or counterclockwise), the number of pulses determines the angular amount of rotation, and a single rotation will output 30 pulses.

In this embodiment, the two output pins are supplied with a high level through two 10K pull-up resistors, which when turned down by means of the internal contacts of the rotary encoder, will generate a falling edge in the level on the pins. Two output pins of the rotary encoder are switched to GPF5 and GPF6 ports of ARM, wherein the GPF5 port is 107 pins of FIG. 3, and the GPF6 port is 108 pins of FIG. 3, and then the signals enter an interrupt trigger circuit of ARM.

In the embodiment, the output pin of the rotary encoder is selectively connected to the interrupt pin of the ARM, so that the execution efficiency can be improved, and the expense of a processor is reduced.

During operation, the register of the ARM is set, interrupt capture is determined as edge detection, when the rotary encoder rotates, the phase relation can be obtained by capturing the time difference of two interrupts, if the time on the port GPF5 is earlier than the time on the port GPF6, the rotary encoder can be judged to rotate clockwise, and if not, the rotary encoder rotates anticlockwise. Then, by reading the number of times the interrupt is triggered, the angular amount of rotation can be obtained, and other devices can be controlled.

The rotary encoder can be pressed, i.e. used as a key switch, in addition to rotating, in this embodiment, the pin of the key output is connected to the GPF7 port, i.e. pin 109 in fig. 3, which is also an interrupt port, and when the rotary encoder is pressed, a falling edge of the voltage level is generated. This falling edge will trigger an interrupt to the CPU to allow the CPU to determine if the rotary encoder has been pressed. The embodiment combines the rotary encoder and the embedded ARM processor, can realize the control effect similar to a flying shuttle single key on other equipment, and becomes a design characteristic of the embedded Linux experimental device.

The rotary encoder used by the device is of a simple mechanical type, and two encoding output ends of the rotary encoder are connected to 2 interrupt pins of the ARM, so that the encoding output can be conveniently read by using an interrupt mode, and the system overhead is saved. The rotary encoder is mainly used for reading and judging the interrupt program based on the Linux operating system, and the method has strong practical significance for learning and understanding the reading and judging method of the interrupt program under the Linux.

(4) The nixie tube adopts 4-bit common-anode type 7-section nixie tubes, adopts a dynamic scanning wiring mode, and is connected to corresponding pins of the embedded ARM core board in a jumper wiring mode.

The nixie tube is realized by adopting a four-digit co-anode nixie tube chip with the model of 3461BS, and a dynamic scanning wiring mode is innovatively used in the connection of the nixie tube and the ARM.

Referring to fig. 4, the nixie tube has 7 segment code interfaces, which are respectively segment code interfaces a to G in fig. 4; the 7 segment code interfaces are connected to the input interface of the seven-bit first short-circuit jumper unit together after passing through a respective 330-ohm current-limiting resistor; the first short jumper cell is PIN2X7 of fig. 4; the output interface of the first short jumper unit is connected to the corresponding GPG ports of the embedded ARM core board, namely GPG 0-GPG 6 ports, which correspond to pins 110, 111, 112, 113, 114, 89 and 90 of FIG. 4.

The nixie tube has 4 bit code interfaces DIG 1-DIG 4; each bit code interface is connected to a collector electrode of a corresponding PNP type triode (with model number 8550), an emitting electrode of the PNP type triode is connected to a positive power supply end, and a base electrode of the PNP type triode is connected to an input interface of a four-bit second short-circuit jumper unit after passing through a 1K resistor; the second short-circuited jumper unit is PIN2X4 of fig. 4; four output interfaces of the second short-circuit jumper unit are connected to corresponding GPG ports of the embedded ARM core board, namely: GPF3, GPF5, GPF6, GPF7 ports, corresponding to

pins

109, 108, 107, and 106 of fig. 4.

The use principle is as follows:

when the ARM outputs a low level on one port (GPF3, GPF5, GPF6 or GPF7 port), the corresponding PNP triode is conducted, the positive power supply is connected to the collector through the emitter of 8550, the corresponding bit of the nixie tube obtains a voltage, and corresponding font coding levels are output through the GPG 0-GPG 6 pins of the ARM, so that corresponding numbers can be displayed on the nixie tube.

In this embodiment, a dynamic scanning mode is adopted, that is, four nixie tubes share one group of segment code interfaces, so as to save cost and reduce pin overhead.

In order to enable the nixie tubes sharing the segment code port to simultaneously display different numbers, the CPU outputs a low-level signal on four pins of GPF3 and GPF 5-GPF 7 of the ARM in a time-sharing manner, so that the four nixie tubes are lighted in turn, and the four nixie tubes are considered to be lighted simultaneously due to the characteristic of visual persistence of human eyes as long as the period of the turn is small enough (not more than 20 ms). When a certain digital tube is lightened, the character pattern coding level is output through GPG 0-GPG 6 pins of ARM, and the digital tube displays the corresponding number. The digital tubes sharing the segment code port with four bits can realize dynamic scanning display by alternate operation.

The nixie tube is dynamically scanned and displayed, so that the power consumption is reduced, the port of the processor is saved, and particularly for an ARM processor of a Linux operating system, the method is an innovative mode and becomes another bright spot in an embedded Linux experimental device.

Therefore, in the device, 7 pins at the segment code end of the 4-bit-sharing-positive 7-segment digital tube are connected to the GPG 0-6 pins of the ARM, and 4 pins at the bit code end are connected to the GPF3 and the GPF 5-7 pins of the ARM after being driven by the triode.

(5) The infrared receiving tube is connected to corresponding pins of the embedded ARM core board in a jumper connection mode;

in fig. 5, the infrared receiving tube is connected to the input interface of the two-bit Short jumper unit (IR _ Short); the output interface of the short-circuit jumper unit is connected to a GPF3 pin (in a multiplexing mode) of the ARM, and the GPF3 pin is the 106 th pin.

The infrared receiving tube is connected with a GPF3 pin of the ARM and is used for verifying and understanding the process that the CPU of the ARM captures and decodes the codes transmitted by the infrared remote controller in an interrupt mode. Aiming at the infrared decoding method based on the Linux operating system, the method is an effective mode for learning the infrared decoding experiment under the Linux operating system.

(6) The temperature sensor adopts a single bus form and is connected to the independent pins of the embedded ARM core board in a jumper connection mode;

referring to fig. 5, the temperature sensor employs a DS18B20 temperature sensor. The temperature sensor DS18B20 is connected in a single bus to the ARM GPF0 independent pin, i.e., pin 105 of FIG. 5.

Specifically, the output of the temperature sensor is connected to the input interface of a two-bit Short jumper unit (namely, 18B20_ Short); and the output interface of the two-bit short jumper unit is connected to the independent pin of the GPF0 of the ARM.

The temperature sensor DS18B20 is connected to a GPF0 pin of the ARM, is used for verifying the support of the Linux operating system on the ARM, is also suitable for learners to write independent single-bus driving programs, and is an effective mode for learning single-bus communication experiments under the Linux operating system.

(7) And the photoresistor is connected with an analog/digital conversion input pin of the embedded ARM core board after being subjected to voltage division by the resistors.

Specifically, referring to fig. 6, the photo resistor is connected to an analog/digital conversion input pin (a _ IN0) of the ARM after voltage division, and the pin a _ IN0 is the pin 103 of fig. 6.

The photoresistor is connected with an analog/digital conversion input pin (A _ IN0) of the ARM after being subjected to voltage division, and is used for verifying the A/D conversion function of the ARM and measuring the light brightness. The method mainly aims at the realization method of the analog-digital conversion based on the Linux operating system, and is a novel and practical mode for learning the analog-digital conversion experiment under the Linux operating system.

(8) The A/D sampling adjustable resistor is connected to an analog/digital conversion input pin of the embedded ARM core board in a jumper connection mode;

specifically, referring to fig. 6, the a/D sampling adjustable resistor is connected to an input interface of a two-bit Short jumper unit (AD _ Short), an output interface of the Short jumper unit is connected to an analog/digital conversion input pin (a _ IN1) of the ARM, and the pin a _ IN1 is the pin 104 IN fig. 6.

(9) The buzzer and the relay are connected to corresponding pins of the embedded ARM core board in a jumper connection mode.

Specifically, the output of the buzzer is connected to an input interface of a two-bit Short jumper unit (BZ _ Short), and an output interface of the Short jumper unit is connected to a UART0_ CTS pin of the ARM, that is, 64 pins of fig. 7;

the output of the relay is connected to the input interface of a two-bit Short jumper unit (RY _ Short), and the output interface of the Short jumper unit is connected to the UART0_ RTS pin of the ARM, namely, the 65 pin of fig. 7.

(10) The keys are respectively connected with 4 interrupt pins of the embedded ARM core board in a jumper wire connection mode by adopting 4 independent keys;

specifically, referring to fig. 8, the 4 independent keys are respectively connected to the 4 independent interrupt pins (GPF3, GPF 4-6) of the ARM through an 8-bit short jumper unit (i.e., key _ short) in a pin multiplexing manner, and GPF3 and GPF 4-6 correspond to

pins

106, 107, 108, and 109 of fig. 8, respectively.

The 4 independent keys are respectively connected to the 4 independent interrupt pins of the ARM, so that verification and understanding of an asynchronous notification mode based on key interrupt under the Linux operating system are facilitated. The method is a simpler and more effective mode for learning various key operation experiments under the Linux operating system.

(11) The serial EEPROM memory is connected to corresponding pins of the embedded ARM core board in a jumper connection mode;

referring to fig. 15, the serial EEPROM memory is of a 24C04 model and is connected to the I2C _ SDA port and the I2C _ SCL port of the ARM through a 4-bit short jumper unit (i.e., 24C04_ short); wherein, the I2C _ SDA port and the I2C _ SCL port are

pins

75 and 74 of fig. 15, respectively.

(12) The I/0 expansion interface is connected to corresponding pins of the embedded ARM core board; the I/0 expansion interface comprises a serial interface, a USB interface, a TF card interface, an RJ45 network interface, an LED interface and an SPI interface;

Specifically, referring to fig. 10, a circuit diagram of a serial port interface is shown; the serial port is connected to UART0 and UART1 interfaces of ARM after level conversion is carried out through MAX232 chips.

Referring to fig. 12, a circuit diagram of a TF card interface is shown; fig. 13 is a circuit diagram of an RJ45 network interface; referring to fig. 14, a circuit diagram of the LED interface and the SPI interface is shown.

The 4 independent LEDs are respectively connected to the GPH 4-7 pins of the S3C2416 in a common anode mode,

(13) the power supply is connected to the power supply pin of the embedded ARM core board after voltage stabilization is carried out through the low-dropout linear voltage stabilization chip.

Referring to fig. 9, a circuit diagram of a power supply is shown, the power supply is powered by 5V, and 3.3V voltage stabilization is performed through a Low Dropout (LDO) linear voltage stabilization chip LM1086, so as to reduce radiation interference caused by the power supply of a switching power supply in a conventional device.

Therefore, the practical embedded Linux experimental device provided by the application has abundant hardware experimental resources and strong wiring flexibility, and can provide a high-efficiency and convenient experimental platform for learners learning the embedded Linux system. The whole learning device is transplanted with the Linux3.6.6 kernel, and learners can conveniently carry out relevant practical learning of drive development and application development on the device.

In specific use, on the basis of hardware resources provided by the experimental device, a character-type drive development experiment, a block-type drive development experiment and a network drive development experiment can be conveniently carried out, and the range of the character-type drive development experiment, the block-type drive development experiment and the network drive development experiment basically covers all the fields of the current embedded Linux drive teaching.

Wherein, this experimental apparatus's key feature lies in:

(1) the 4-digit nixie tube dynamic scanning module introduced into the embedded Linux system experimental device can make learners fully exert their own flexibility to carry out experiments. The effect is better through practical application, and the Chinese medicinal preparation is accepted and welcomed by learners.

(2) The experimental device uses a rotary encoder, and also belongs to innovation in similar products. The embedded Linux drives the rotary encoder, so that a learner can conveniently design various interactive applications, for example, the learner can be used for quickly selecting music in a designed music player, and the actual application range of the experimental device is widened.

(3) On the basis of the experimental device, the device can smoothly complete the following experiments based on embedded Linux:

1. and output control experiments, such as an independent LED experiment (for switching value display), a buzzer experiment (for providing alarm), a relay experiment (for controlling an electric appliance), a digital tube dynamic scanning experiment (for displaying numbers), a liquid crystal display experiment (for displaying information through a UI interface), an audio output experiment (for outputting sound) and the like.

2. Input-type reading experiments, such as an independent key experiment (for acquiring switching value input), a rotary encoder experiment (for flying shuttle single-key input control), an adjustable resistance experiment (for reading analog/digital conversion), an infrared receiving tube experiment (for infrared decoding), a microphone experiment (for audio input), a touch screen experiment (for reading resistive touch screen input), and the like.

3. Communication experiments, such as network communication experiment (for verifying network communication), serial communication experiment (for verifying serial communication), SPI communication experiment (for verifying SPI interface communication), AT24C02 experiment (for verifying I)²C-interface communication), etc.

4. Sensor type experiments, such as DS18B20 experiments (for temperature measurement), photoresistors (for light intensity measurement), and the like.

5. Storage experiments, such as TF card experiments (for verifying data access), USB port experiments (for verifying USB port communication and USB disk access functions), and the like.

In the experimental device, a plurality of Linux kernel versions can be transplanted. In practical application, the kernel transplanted by the device is Linux3.6.6 version. Practice proves that the kernel of the version is transplanted to the experimental device to be very stable, and the experimental requirements of embedded Linux learners can be met. Meanwhile, the experimental device also supports learners to transplant Linux kernels of other versions by themselves, and provides a good experimental platform for kernel transplantation.

To sum up, the utility model provides a practical embedded Linux experimental apparatus has following advantage:

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be viewed as the protection scope of the present invention.

Claims

1. A practical embedded Linux experimental device is characterized by comprising an embedded ARM core board, an audio input/output interface, a liquid crystal display, a touch screen, a rotary encoder, a nixie tube, an infrared receiving tube, a temperature sensor, a photoresistor, an A/D sampling adjustable resistor, a buzzer, a relay, a key, a serial EEPROM memory, an I/0 expansion interface and a power supply;

2. The practical embedded Linux experimental apparatus of claim 1, wherein the I/0 expansion interface comprises a serial port interface, a USB interface, a TF card interface, an RJ45 network interface, an LED interface, and an SPI interface;

3. The practical embedded Linux experimental apparatus of claim 1, wherein the nixie tube has 7 segment code interfaces, the 7 segment code interfaces are connected to an input interface of a first short-circuit jumper unit with seven bits after passing through a respective current-limiting resistor, and an output interface of the first short-circuit jumper unit is connected to a corresponding GPG port of the embedded ARM core board;

4. The practical embedded Linux experimental apparatus of claim 1, wherein the 1 st encoded output and the 2 nd encoded output of the rotary encoder are each connected to a positive power supply terminal through a pull-up resistor; meanwhile, the 1 st coding output end and the 2 nd coding output end of the rotary coder are respectively connected to an interrupt port of the embedded ARM core board; and the press output end of the rotary encoder is connected to an interrupt port of the embedded ARM core board.