ADS1299 - "Read data continuous" vs "Continuous conversion mode"

Hi Devon,

Allow me to clarify:

Continuous Conversion Mode vs. Single-shot Mode are the two sampling options offered in the ADS1299. Conversely, RDATAC vs. RDATA Mode are the reading data options and only affect when the output shift register is refreshed with new data.

The two sampling options determine whether the ADC is sampling the input voltage constantly at the modulator rate (fMOD) or only on demand. Because delta-sigma ADCs require a history of previous samples, the digital filter takes some time to settle when the modulator begins converting. In Continuous Conversion Mode, the digital filter output settles after 4 samples and every sample thereafter is considered "valid" data. Single-shot Mode, however, is used to convert one sample at a time and is controlled by sending the START SPI command or by toggling the START pin. Each time you do this, the digital filter will reset and need to settle for 4*tDR before data is output.

In RDATAC (Read Data Continuous) Mode, the output shift register in the ADS1299 is loaded with new data after every conversion, as indicated by the falling edge of /DRDY. This is the default mode for reading data and can be used if you do not need to constantly read/change register settings and is best used for data logging applications. If all the data is not read before the next /DRDY falling edge, you will lose the LSBs of the old data and start reading in the MSBs of the new data.

RDATA Mode, on the other hand, is for reading the data on demand. You may send the RDATA command after each /DRDY to read the data without worrying about completing the read before the next sample is ready. This is often used for applications that require reading/writing registers in between samples.

I hope that makes sense. Let me know if you still have any questions.

Best Regards,