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DAC8742H: HART speed and frame when use SPI interface

user5128412
Prodigy 10 points
Part Number: DAC8742H

       What is the HART MOD_OUT speed rate range  when MCU connect to DAC8742 by SPI interface？The speed is fixed at 1200bps or software programed by SPI speed?With SPI interface,I think the MCU  must have a HART protocol stack，the MCU must sent the start bit,8bit data,one parity and a stop bit by SPI?Is it right or not? 

       In HART mode,the  amplitude of MOD_OUT can be adjust 400~800mv by Register or fixed 460mv?

       Thanks.

 

  • 0
    TI__Mastermind 46290 points

    Hello,

    HART communication is specifically based on 1200 BAUD FSK - therefore the frequency of communication at MOD_OUT is fixed regardless of whether one uses the SPI interface or the UART interface. In SPI mode, since the SPI input/output frequency does not necessarily match the MOD_OUT frequency, the continuous datastream at MOD_OUT is achieved through the internal TX and RX FIFOs and their associated level-sensitive alarms.

    The MCU must send the complete HART packet.

    When using the SPI interface the amplitude of the HART FSK output may be adjusted.