Circuit Design of Speech Recognition Robot System

　　At present, industrial robots have considerable market potential in the manufacturing industry. To make industrial robots truly applied to various aspects of the production line and meet people's growing needs, high-performance voice recognition control systems are indispensable. With the rapid development of computer hardware and software technology, semiconductor technology, electronic technology, communication technology, etc., humans have entered the post-PC era. Voice recognition technology has developed rapidly, and various products supporting voice recognition have been launched. Humans have realized the use of voice commands to control air conditioners, televisions, lights, automatic curtains, etc., making people's lives "as they please", more comfortable and more convenient. A robot with voice recognition function was designed based on the Lingyang 16-bit SPCE061A microcontroller. After training, the robot responds to the trainer's commands and completes actions such as dancing two dances, walking, turning, turning the head, and launching frisbees.

　　Speech recognition can be divided into two processes: training and recognition. In the first stage, the speech recognition system learns human language and stores the learning content in a speech library. In the second stage, the current input speech can be searched for the corresponding word meaning or semantics in the speech library. Lingyang's 16-bit SPCE061A microcontroller has built-in 32K words of flash memory, 2K words of SRAM, built-in 10-bit ADC and DAC , and up to 14 interrupt sources. Its CPU core uses a 16-bit microprocessor chip with DSP function, and the CPU can work at a maximum frequency of 49MHz. It can process complex digital signals very easily and quickly. Therefore, compared with other types of microcontrollers, SPCE061A has more advantages in digital speech processing. A robot with speech recognition function was designed based on SPCE061A. After training, the trainer can use various commands to make the robot complete many interesting actions, making human-computer interaction more intelligent.

　　SPCE061A minimum system

　　The SPCE061A minimum system contains the basic modules around the SPCE061A chip, which are mainly composed of the crystal input module (OSC), the phase-locked loop peripheral circuit (PLL), the reset circuit (RESET), the indicator light (LED), etc., see Figure 4-1. Connect the crystal oscillator and the resonant capacitor to the OSC32O and OSC 32I ports, and connect the corresponding capacitor and resistor to the VCOIN port to work. The other unused VDD ports and GND ports should not be left floating and should be connected to a 0.1uF coupling capacitor to improve the anti-interference ability. Figure  4-1  SPCE061A minimum system.

　　Clock circuit design

　　The clocks, real-time clock delays and other time-related products in daily life use 32768Hz real-time clocks. The crystal oscillator used in the SPCE061A clock circuit uses an external crystal with a frequency of 32768Hz. The connection diagram of the SPCE061A clock circuit can be found in the figure.

　　Phase-locked loop circuit design

　　Phase Lock Loop is to multiply the 32768Hz real-time clock (RTC) to adjust the system clock Fosc to 49.152MHz, 40.96MHz, 32.768MHz, 24.576MHz or 20.480MHz. For
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　Power Module

　　The power input port is the energy supply center of the 61 board. The power of the entire board is provided from here. A battery or a voltage regulator can be used to provide 5V input, and the current must be at least 50mA, otherwise the system will not be able to multiply and download errors will occur. The core power supply of SPCE061A is 3.3V. Since the I/O port can be connected to 3.3V or 5V, there is a port level selection jumper J5 in the power module to select the port voltage. The power module is shown in the figure below:

　　Since the port high level required by this system is 5V, the J5 jumper in the figure needs to be jumped to 1 and 2.

　　Playback circuit design

　　The voice data stored in HM628128A is taken out in sequence, decoded, and D/A converted and output at a rate of 8kHz. The voice data is restored to the original voice waveform through capacitor filtering, and finally the speaker is driven by a transistor to play the sound. SPCE061A audio output has two DAC channels. The analog electrical signals output by DAC1 and DAC2 are output through the DAC1 and DAC2 pins. The output range of DAC is 0x0000~0xFFFF. The output data of DAC1 and DAC2 should be written into P_DAC1 and P_DAC2 units. After power-on reset, both DACs are automatically turned on, and a small amount of current (several milliamperes) will be consumed at this time. If not needed, try to turn off the DAC output (set the first position of the P_DAC_Ctrl unit to 1). In addition, the DC voltage of the DAC must change smoothly, otherwise the speaker may produce noise due to sudden changes in voltage. In order to slow down the voltage change and output high-quality audio data, the ramp up/down technology can be used. Its application condition is: when the DAC is used for the first time after being awakened/powered on reset, the power-on reset function should be before being turned off/entering the sleep state. The sound playback uses the DAC inside the SPCE061A. See Figure 4-8 for the circuit  . The SPY0030 in the figure is a product of Lingyang. Compared with the LM386, the operating voltage of the LM386 needs to be above 4V, while the SPY0030 only needs 2.4V (two batteries) to work; in terms of output power, the LM386 is only above 100mW, while the SPY0030 can reach 700mW.

　　Robot hardware drive circuit

　　The robot driving circuit uses a high-power transistor to form an H-bridge to drive the motor to achieve forward and reverse rotation of the motor. The motors driven by the H-bridge in this system include two motors for walking and one motor for head turning. At the same time, a transistor is used to drive unidirectional rotating motors, such as the acceleration motor and the launch motor.

　　Speech processing technology itself is a comprehensive subject with strong theoretical, wide practical and difficult aspects. It is also quite difficult to develop a single-chip microcomputer with speech function. Lingyang UNSP series 16-bit single-chip microcomputer is designed to meet this demand. Lingyang SPCE061A realizes speech recognition. Its uniqueness lies in: simple hardware circuit, because SPCE061A is a single-chip microcomputer specially designed for speech signal processing, microphone and speaker can be directly connected, and the amplifier circuit does not need to be connected externally. It has a set of efficient instruction systems, easy software programming, and corresponding API functions that can be called directly.