8.5.4.1 Manual Data Read Mode

In manual data read mode, data are read by issuing the RDATA command. The ADS112U04 responds to the RDATA command with the latest conversion data. There are three ways to monitor for new conversion data.

One way is to monitor for the falling edge of the DRDY signal. To configure the GPIO2/DRDY pin to output the DRDY signal, the pin must be configured as an output by setting the GPIO2DIR bit in the configuration register, and DRDY must be multiplexed to the pin by setting the GPIO2SEL bit in the configuration register.

Figure 62 shows the timing diagram for collecting data in manual data read mode using DRDY to indicate new data.

Figure 62. Manual Data Read Mode Using DRDY (Continuous Conversion Mode)

Another way to monitor for a new conversion result is to periodically read the DRDY bit in the configuration 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 ADS112U04 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 a UART transmission, the transmission is not corrupted. The new data are loaded into the output shift register upon the following RDATA command.

Figure 63 shows the timing diagram for collecting data in manual data read mode using the DRDY bit in the configuration register to indicate new data.

Figure 63. Manual Data Read Mode Using the RREG Command (Continuous Conversion Mode)

The last way to detect if new conversion data are available is through the use of the conversion data counter word. In this mode, the host periodically requests data from the device using the RDATA command and checks the conversion data counter word against the conversion data counter word read for the previous data received. If the counter values are the same, the host can disregard the data because that data has already been gathered. If the counter has incremented, the host records the data. The rate at which the host polls the ADS112U04 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 a UART transmission, the transmission is not corrupted. The new data are loaded into the output shift register after the following RDATA command.

Figure 64 shows the timing diagram for collecting data in manual data read mode using the conversion data counter word to indicate new data.

Figure 64. Manual Data Read Mode Using the Conversion Data Counter (Continuous Conversion Mode)

The conversion data counter can be used in conjunction with the previously discussed methods of detecting new data to ensure that the host did not miss a conversion result.