8.5.4 Reading Data and Monitoring for New Conversion Results

Conversion data are read by issuing the RDATA command. The ADS1219 responds to the RDATA command with the latest conversion result. There are two ways to monitor for new conversion data.

One way is to monitor for the falling edge of the DRDY signal. When DRDY falls low, a new conversion result is available for retrieval using the RDATA command. Figure 39 shows the timing diagram for collecting data using the DRDY signal to indicate new data.

Figure 39. Using the DRDY Pin to Check for New Conversion Data

Another way to monitor for a new conversion result is to periodically read the DRDY bit in the status register. If set, the DRDY bit indicates that a new conversion result is ready for retrieval. The host can subsequently issue an RDATA command to retrieve the data. The rate at which the host polls the ADS1219 for new data must be at least as fast as the data rate in continuous conversion mode to prevent the host from missing a conversion result.

If a new conversion result becomes ready during an I²C transmission, the transmission is not corrupted. The new data are loaded into the output shift register upon the following RDATA command.

Figure 40 shows the timing diagram for collecting data using the DRDY bit in the status register to indicate new data.

Figure 40. Using the DRDY Bit to Check for New Conversion Data