Application of ADl871 Analog-to-Digital Converter in Data Acquisition System

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description:

The development of science and technology puts higher and higher requirements on the sampling rate, resolution, accuracy, interface and anti-interference ability of the data acquisition system.

The AD1871 is a 24-bit ADC with outstanding data on dynamic range, sampling rate and sampling accuracy. Its introduction provides a better solution for designing high-speed, high-precision data acquisition systems. Since its output is a serial output, when it is directly connected to the MCU, the sampling rate of the sampling system is greatly reduced.

If the actual maximum rate of the I/O port of the MCU is 1MHz (the rate of the MCU is usually of this order), the minimum time interval for the I/O terminal 13 to transmit 1Bit is 1μs. When the ADl871 outputs 2 channels of 24Bit, the actual string is required. The line output is 64Bit, so the sampling rate drops to 1MHz/64=15.625kHz. This rate is much lower than the 96kHz of ADl871. In addition, when the MCU reprocesses 64-bit serial data into two 24-bit parallel data, the speed will further. reduce.

To this end, the author uses the field programmable gate array (FPGA) to design the interface between ADl871 and MCU, the FPGA completes the control of ADl871, and the serial data of its output becomes parallel data inside the FPGA, after parallel The data is sent to the MCU in groups of 8 or 12 bits. Since the actual transmission rate of the FPGA can meet the transmission rate requirements of ADl871, the above "bottleneck" can be solved.