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DAC161S997EVM: Programming the DAC161S997 SPI using external MCU

Karan kaushik
Prodigy 40 points
Part Number: DAC161S997EVM
Other Parts Discussed in Thread: DAC161S997

Hi,

I want to connect the DAC161S997 SPI of the EVM board with a different MCU (Arduino in this case).

The problem is that I can't find an access to the CSB pin of the DAC.

My question is that is there a way to connect the DAC IC of the EVM with a different MCU (other than on-board MSP4430) or do I have to get a separate DAC161S997 in order to work with it?

If so, how would I go about doing it? There are open pins for SCK, MISO, MOSI  but no CSB. And also, do I have to disable the MSP4430 some how?

Thanks,

Karan

  • 0
    TI__Expert 5820 points
    Hi Karan,

    The CSB pin is not connected to a header on the EVM according to the schematic in the user's guide. However, you can still access this pin because there is a pull-up resistor between the CSB net and VDD (R13). You can connect a wire to the CSB side of R13 to interface the CSB pin with an external MCU.

    Thanks,
    Garrett
  • 0 in reply to Garrett Satterfield
    Prodigy 40 points
    The CSB is a active low pin, even if I connect my SS pin on the arduino to the R13, will I be able to Interface with the SPI since CSB is hardwired to the VDD.
    Do I have to disable the MSP4430 somehow, or just not connecting the USB will work?
    The user guide is pretty hollow.
    Thanks
  • 0 in reply to Karan kaushik
    Prodigy 40 points
    cont...
    Ive actually tried interfacing with the SPI while connecting the CSB (on the R13 side) to my SS pin but there still doesn't seem to be any response. Could there be something that I'm missing or is the DAC161 IC on the EVM board not meant to be used with other microcontrollers?

    Karan
  • 0 in reply to Karan kaushik
    TI__Expert 5820 points
    Hi Karan,

    R13 is a large pull-up resistor so it is not tying CSB to VDD. When the MCU pin goes low it will still be able to pull down the CSB pin. The issue might be that the on board MSP430 is holding this pin high so the external MCU is not able to pull it down. If this is the case, the only option would be to cut the trace between P2.0 on the MSP430 and the CSB pin of DAC161S997 or perhaps remove the MSP430 entirely. Can you provide waveforms of SCLK, MOSI, and CSB when you are trying to transmit from the external MCU? The EVM was designed to evaluate the device with the EVM software so I don't think using an external MCU was considered.

    Thanks,
    Garrett
  • 0 in reply to Garrett Satterfield
    TI__Expert 5820 points
    Hi Karan,

    Do you have any update on this?

    Thanks,
    Garrett