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DAC8742H: Burst command, HART

Oba
Mastermind 18025 points

Part Number: DAC8742H

Hello,

Does DAC8742 support "burst command" of HART communication?
If it supports the command (or has an example) and depends on the software implementation,
it would be appreciated if you could share some tips on how to implement the software such as resigter seeting etc. The interface with the CPU is in SPI mode.

Regards,
Oba

  • +1
    TI__Guru** 100755 points

    Oba-san,


    The DAC8742H supports burst communications, along with all other HART communications that use the FSK signaling. However, this is all implemented through the microcontroller code. The DAC8742H only translates between the HART FSK and the SPI or the HART FSK and the UART. The SPI and UART is then interpreted by the microcontroller and sent back to the device to respond through HART FSK.

    If HART is sent and received through UART, the microcontroller can just use UART for receiving and sending data. However, if the HART is sent and received through SPI, the DAC8742H uses 16 byte receive and transmit FIFOs. Flags can be used as interrupts to show when the FIFO is full or empty, and the device can be read to determine how full the FIFO is. The microcontroller must be used to manage the data received and transmitted to the HART channel to make sure that data is not lost.

    In the past, we have contracted with a third party to write the firmware for the HART communications. Because this HART stack was not written by TI, we don't have any example code to give out to customers. Smart Embedded Systems (https://www.smartembeddedsystems.com, Pleasanton, CA) wrote an original HART stack for the DAC8742H). We have often recommended them to write firmware for our devices, so they are very familiar with how they work.


    Joseph Wu