1、如果是單片機控制一個ad7793，那么使用檢測drdy引腳低電平來檢測adc是否轉換完成。
2、如果是單片機控制多個ad7793，那么不能使用檢測drdy引腳低電平來檢測adc是否轉換完成，因為此時DRDY引腳是高阻態，無法檢測低電平。
英文如下：
Yes, you can use this on a shared SPI bus. Please take note that when /CS is taken high, the DRDY pin is tri-stated. Therefore, the DRDY pin will not indicate the end of conversion. If you want to use a single SPI controller on your multiple ADCs please refer to this thread https://ez.analog.com/data_converters/precision_adcs/f/q-a/26356/how-do-i-interface-to-multiple-ad779x-adcs-over-the-same-serial-interface for further information.
I would suggest to use a single MCLK for the multiple devices, meaning one ADC can use its internal clock and output this to use as MCLK input for the other devices. In this configuration, you will ensure synchronization with multiple devices with a maximum of 1 MCLK difference only. So you only need to monitor the DRDY pin of the 1st device, when DRDY goes low, read its conversion, at this point the other ADCs will also available and you can read the conversion for other devices.
Thanks,
解決的方案是，讀取特定ad7793的轉換完成標志位，芯片寄存中有特定的寄存器可以檢測，因此相對來說，沒有讀取引腳電平快，但是也是一個解決方案。
其實，某種程度上，如果是用片選來切換ad7793，那么用多路開關來切合讀取的adc通道，才是比較好的方式，多個ad7793顯得浪費，軟件上都是一個一個通道一次讀取的，除非多個spi設備。