/*!
    \file    readme.txt
    \brief   description of serial SPI interface and regular conversion

    \version 2025-07-15, V1.0.0, firmware for GD32G5x3
*/

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*/

  This demo is based on the GD32G553Q-EVAL-V1.0 board, it shows the HPDF sample stream data
by serial SPI interface. In this demo, configure channel0 as is serial channel to receive the
data stream. The SPI0 is used as sigma-delta modulator to transmit stream data and provide
external clock. The CKIN0 pin is connected to PC0, the DATA0 pin is connected to PC1.

  This demo shows the process of the HPDF receiving and smoothing the SPI serial data stream. If the
HPDF output data exceeds the threshold monitor high/low threshold or malfunction monitor
counter, the error information will be printed. If the HPDF output data dose not exceed the
threshold, the HPDF output data will be printed by USART0.

  Connect SPI0 SCK  PIN(PA5) to HPDF CKIN0  PIN(PC0).
  Connect SPI0 MOSI PIN(PA7) to HPDF DATAIN0 PIN(PC1).
