Today, with the rapid development of information, computer information technology has become a dominant technology, and the information industry has also become a leading industry. The information industry has become a new economic growth point in today's society. To this end, this paper aims at how to design acquisition systems and terminals. Circuit design is discussed.
Data acquisition system circuit
High-speed, high-precision interface circuit design for parallel port communication between 18-bit AD7674 and C8051F060. The adopted single-chip microcomputer has flexible configuration, fast transmission speed, and the interface adopts parallel port communication, which can realize high-speed data transmission of embedded data acquisition system. At the same time, AD7674 is connected with 18-bit SAR ADC such as AD7678 and AD7679 and 16-bit high-speed SAR ADC such as AD7621 and AD7623. Compatible, which greatly enhances the flexibility and scalability of system development.
The AD7674 offers three different slew rate modes to optimize performance for different specific applications. These three modes of operation are as follows: WARP, which allows sampling rates up to 800 kHz. However, in this mode, the accuracy of the conversion can be guaranteed only when the time between conversions does not exceed 1 ms. If the time between two consecutive conversions is greater than 1 ms, the result of the first conversion is ignored and this mode is suitable for applications that require fast sample rates. NORMAL, the sampling rate of this mode is 666 kHz, in this mode there is no limit to the time between sample conversion, which guarantees high conversion accuracy and ensures fast sampling rate. IMPULSE, a low power mode with a sampling rate of 570 kHz.
Only one C8051F060 chip can complete various control of single-chip 8051, multi-channel A/D conversion and D/A conversion, I2C, SPI data bus transmission, RS232, RS485 serial communication and other functions, thus greatly reducing the components The type reduces the area of ​​the printed board, saves costs, and improves system reliability. The configuration of the crossbar switch mode makes the I/O port application more flexible and convenient. The interface circuit diagram of AD7674 and C8051F060 is the peripheral circuit and interface circuit of AD7674 in high-speed acquisition system. Peripheral circuits include the design of voltage reference inputs, the design of analog voltage input sections, the design of analog and digital power supplies, and the design of interface circuits. The interface circuit includes the interface between the AD7674 and the C8051F060 and CPLD.
Ethernet terminal design
The CS8900A low-power Ethernet controller is widely used in industrial computers. Its highly integrated design (which requires very few external components in the application) and a simple bus interface make it ideal for this design. At present, many Ethernet controllers only provide PCI (peripheral component expansion interface) interface, and CS8900A can be directly connected to the microcontroller. Therefore, the CS8900A can be directly controlled by the I/O port of MSP430F149. The specific connection method is as follows. Figure 2 shows. In addition, the CS8900A can be powered directly from 3V, which facilitates level matching with the MSP430F149.
Figure 2: Hardware circuit schematic
Speech recognition circuit module design
The core processing unit of the module uses ST's 32-bit processor STM32F103C8T6 based on ARMCortex-M3 core. This module takes the dialogue management unit as the center, realizes the voice recognition function through the hardware unit with LD3320 chip as the core, and adopts the embedded operating system μC/OS-II to realize unified task scheduling and peripheral device management. After a large number of experimental data verification, the speech recognition module designed in this paper has the advantages of high real-time performance, high recognition rate and high stability.
Speech recognition circuit
Figure 3 is a schematic diagram of the speech recognition part, which is designed with reference to the LD3320 data sheet published by ICRoute. The LD3320 integrates a fast and stable optimization algorithm, which does not require external Fla-sh and RAM. It does not require user training and recording to complete non-specific speech recognition, and the recognition accuracy is high. In the figure, LD3320 is directly connected to STM32F103C8T6 in parallel mode, and all use 1kΩ resistor pull-up. A0 is used to judge whether it is data segment or address segment; control signal, reset signal and interrupt return signal INTB are directly connected to STM32F103C8T6, using 10kΩ resistor Pull, the auxiliary system works stably; the STM32F103C8T6 uses the same external 8 MHz clock; the LEDs D1 and D2 are used for the power-on indication after reset; the MBS (pin 12) is used as the microphone bias, and an RC circuit is connected to ensure Output a floating voltage to the microphone.
Editor's comment: With the rapid development of science and technology, embedded information technology has received more attention. The advancement of technology will bring huge social benefits. It plays an important role in accelerating social progress and enhancing information exchange, and it is also imperceptible. The impact of human life, from data acquisition, Ethernet terminals, speech recognition circuits can better reflect its subtleties.
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