When the RDATA command is sent, the data are retrieved from the ADC data-holding register. Read data at any time without the risk of data corruption because the command method does not require synchronizing to DRDY. Polling of DRDY to determine when ADC data are ready can still be used.
Figure 91 shows the read data by command sequence. The output data MSB begins on the first SCLK rising edge after the command. The output data field can be 2, 3, or 4 bytes long. The data field consists of an optional STATUS byte, three bytes of conversion data, and an optional CRC byte. An RDATA command must be sent for each read operation. The ADC does not respond to commands until the read operation is complete, or terminated by taking CS high.
After all bytes are read, the data-byte sequence (including the STATUS byte and CRC byte, if selected) is repeated by continuing SCLK.