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ADS8363EVM: Pulling Register Information

Part Number: ADS8363EVM
Other Parts Discussed in Thread: ADS8363, , TMS320C6748

Hello,

My group and I, as im sure youll be able to tell, have limited background with SPI communication. We are trying to complete a simple task with this board which is to pull the default value of the REFDAC1 register which is known to be 07FF. We have tried following the data sheet but seem to be getting unusual outputs. Attached is a screenshot of those ouputs along with our inputs. Any insight would be appreciated along with any other resources or examples you would recommend for beginners.

Regards,

Brian Dougenik

  • Hi Brian,

    My first impression - the ADS8363 BUSY and MISO outputs should not be looking like the same signal, and neither should have outputs that are 1/2 clock cycle wide. What sort of hardware are you working with? Is it our EVM or is it a board of your own making?
  • Tom,

    Thanks for the quick reply! We are using the ADS8363EVM which is connected to an Analog Discovery 2 which we are using for the SPI communication.

    Thanks,
    Brian Dougenik
  • Hi Brian,

    When you access the CONFIG register, you should be setting R[1:0] = 01 to update all CONFIG register contents and A[3:0] = 0011 to read REFDAC1. From Figure 38, it looks like the rising edge of your first clock in the command should align with the falling edge of CONVST and RD (tied together).

    After completing the 20-clock access cycle, the next 20 clocks should output the REFDAC1 register contents on SDOx.

    Can you clarify whether you are using full-clock mode or half-clock mode? And what are the settings of M0 and M1?

    Best regards,
  • Ryan,

    I believe the board is defaulted to half clock mode so I would say that we are operating in that mode. We have not set the M0 or M1 bits so I would assume these are the default values as well. This may sound like a ridiculous question but do we need to connect power to the board to read the register contents through SPI? We tried to connect power and ground to the J4 header as instructed in the user guide for the evm, however the header does not have any visible pinouts on the board. We are electrical engineers with minimal experience in embedded systems but our senior project is based on this subject so it would be helpful to have a step by step instruction for something as simple as reading the refdac register so we can use that knowledge to move on to doing more advanced things with it (i.e connecting to the TMS320C6748 DSP).

    Thanks,

    Brian

  • Hi Brian,

    Assuming you have just the ADS8363EVM, you would need to apply power to the board to read out the register contents. You would need to (ideally) find a mating connector to the 10-pin female header at J4. You could also solder bus wires to the ferrite beads (FB1 and FB2) and apply your AVdd and DVdd voltage there.
  • Hi Brian,

    Have you gotten anywhere with this ADS8363 issue yet?