Evaluate the DRDY bit to determine
when new conversion data are available for readout. Use one of the following two
methods to evaluate the DRDY bit:
- The controller periodically
reads the STATUS_MSB register to poll the DRDY bit. If the DRDY bit is set,
indicating that a new conversion result is ready for retrieval, the
controller subsequently issues an RDATA command to retrieve the data.
- With the STATUS header output
enabled, the host periodically issues an RDATA command to receive the STATUS
header together with the conversion data within the same I2C
transaction. If the DRDY bit in that transaction reads 1b, the received
conversion data are new. If the DRDY bit is 0b, the host discards the
conversion data received in that transaction because the same conversion
result has been read previously. In addition, the conversion counter
transmitted as part of the STATUS header indicates the count of the
conversion that is retrieved within the current I2C transaction.
The host controller can evaluate the conversion counter to understand if the
host read the same conversion result multiple times or if the host missed to
read a conversion result.
To avoid missing data, evaluate the DRDY bit at least as often as the output data
rate.