This article presents the design of a multi-channel data acquisition and storage system based on the TMS320F2812 DSP and the ADS8365 analog-to-digital converter. The system is designed to collect and store high-speed, precise analog signals from multiple channels efficiently.
The TMS320F2812 is a high-performance 32-bit fixed-point digital signal processor from Texas Instruments, part of the C28x series. It features a clock speed of up to 150 MHz and includes various communication interfaces such as I2C, SPI, CAN, and PWM, making it ideal for industrial control applications. The TL2812-EVM development board provides a flexible platform for evaluating the performance of the TMS320F2812 core module, featuring a two-layer PCB with a gold-free process and a compact size of 185mm x 135mm. Its robust design ensures compatibility with both high and low-temperature environments, making it suitable for industrial use.
The ADS8365 is a high-speed, low-power, six-channel simultaneous sampling ADC that operates on a single +5V supply. It can achieve a maximum sampling rate of 5 MHz and includes six differential sample-and-hold amplifiers along with an 80dB common-mode rejection ratio. It also features a 2.5V reference voltage and a high-speed parallel interface, making it well-suited for applications requiring fast and accurate signal conversion.
In this system, the TMS320F2812 communicates with the ADS8365 using direct address read mode, where the XA[2:0] pins are used as the lower address bits for the conversion result registers. The CS pin controls the data bus, which goes into a high-impedance state when high and outputs data when low. The CLK signal for the ADS8365 is generated by the T1PWM output of the TMS320F2812, while the GPIOB14 pin is used to synchronize the three ADC sample/hold modules via HOLDA, HOLDB, and HOLDC signals. The EOC (End of Conversion) signal triggers an external interrupt on the TMS320F2812, initiating the data read process.
To support more channels, the CS address expansion of the ADS8365 is managed through the lower address lines of the TMS320F2812. Additionally, the front-end signal conditioning circuit uses the OPA227 operational amplifier to adjust the ±5V sensor output to the ±2.5V input range of the ADS8365. This circuit improves signal integrity and reduces noise interference, ensuring accurate data acquisition.
The software design for the TMS320F2812 utilizes a C-language environment, simplifying development and improving code readability. The program flow begins with system initialization, including watchdog configuration, clock setup, and RAM configuration. Then, the GPIOs are configured for communication with the ADS8365, and the interrupt vector table is set up to handle the EOC signal. Once initialized, the system waits for the ADC to complete its conversion and then reads the results from the ADC registers.
The system has been successfully applied in projects such as brushless doubly-fed motor control systems, demonstrating its capability in handling high-precision, real-time data acquisition. It is also suitable for applications like motor control, multi-axis positioning, and multi-channel data acquisition, meeting the demands of high-speed alternating voltage signal processing. The design effectively solves the challenge of synchronous sampling of physical quantities, proving to be a reliable and efficient solution for complex industrial applications.
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