8.5.1.5 Data Retrieval

Data retrieval can be accomplished in one of two methods. The read data continuous command (see the RDATAC: Read Data Continuous section) can be used to set the device in a mode to read the data continuously without sending opcodes. The read data command (see the RDATA: Read Data section) can be used to read just one data output from the device (see the SPI Command Definitions section for more details). The conversion data are read by shifting data out on DOUT. The MSB of the data on DOUT is clocked out on the first SCLK rising edge. DRDY returns to high on the first SCLK falling edge. DIN should remain low for the entire read operation.

The number of bits in the data output depends on the number of channels and the number of bits per channel. For the ADS1292R, the number of data outputs is (24 status bits + 24 bits × 2 channels) = 72 bits. The format of the 24 status bits is: (1100 + LOFF_STAT[4:0] + GPIO[1:0] + 13 '0's). The data format for each channel data is twos complement, MSB first. When channels are powered down using user register settings, the corresponding channel output is set to '0'. However, the sequence of channel outputs remains the same.

The ADS1291, ADS1292, and ADS1292R also provide a multiple readback feature. Data can be read out multiple times by simply giving more SCLKs, in which case the MSB data byte repeats after reading the last byte.