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ADS1241: Data transmission

Carlo
Expert 7715 points

Part Number: ADS1241

Hi E2E,

Good day.

How does the ADS1241 know the difference between an OPCODE and Address? For example how it differentiates RDATAC (Read Data) Opcode versus the MUX register address, both are 0x01?

Do we wait for DRDY after sending each command and data for next? Or can we send one command/data after another? How does the IC know which is MUX and which is RDATA?

Regards,
Carlo

  • 0
    TI__Guru** 113765 points

    Hi Carlo,

    The RDATA is a single byte command.  The WREG and RREG commands are 2 byte command sequences.  When writing the mux, there is a WREG command that precedes it followed by which register(s) is to be written.  The communication is framed with CS.  Using CS is the best way to ensure that the communication is correct.  If CS is tied low, then there is the possibility that the communication can get out of synchronization.

    If the WREG command is issued, the ADS1241 will be looking for the 2nd byte of the command sequence.  Toggling CS at any time during the communication will reset the communication until the CS goes low.  When the WREG command is transmitted, the internal state machine is waiting for a valid register(s) to be written.

    The RDATA command is decoded and the last conversion data is placed onto the output buffer waiting to be clocked out of the device.  There are delay periods required so that the command can properly decode before the data becomes available.  There are also times where you need to wait between commands.  The timing is shown in the Timing Characteristics Table on page 6 of the ADS1241 datasheet as t6 and t11 depending on the operation.

    Best regards,

    Bob B