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fail to use bitwise mode in ADS5294

Other Parts Discussed in Thread: ADS5294, ADS5295

Hi, i'm using ADS5294. When i write command X"0100" to address X"28" to select bit-wise readout mode, it always turns out to be the byte-wise mode. I'm sure that the register is configured successfully because modifications to other registers work well. Has anybody  successfully used the bit-wise mode for ADS5294?

Thanks very much!

  • Hi,

    I am seeing something similar to what you are reporting when I use the TSW1400 capture card.  Are you using this or the TSW1250?  I am consulting with the design team.  Perhaps there is another bit that must be set that is not documented in the datasheet.  I will follow up with you soon.

    Regards,

    Christian

  • I'm using a board designed by myself. I tried to read back the content of "bitwise" register, and it turned out to be:

        write                    read
     0xFFFF                 0xFFFF
     0x0FFF                 0x0000
     0x8FFF                 0x8FFF
     0x8100                  0x8100
    It seems that only when bit 15 = '1' , the write command will take effect. By the way,  write and read operations for other registers are correct.
    I'm looking forward to your good news. 
    Regards, Weibin
  • Hi,

    Yes, I have confirmed the same on my setup and GUI:  REG 0x28 readback is only possible when bit 15 is set to 1. Same applies to register 0x42 but not other registers such as Reg 0x25.  I am consulting with design so that we can document this in the datasheet.  I will inform once I learn something.

    Regards,

    Christian

  • Hi,

    I was told that bit-wise mode should be enabled as described in the ADS5295 datasheet on page 37 which shows that REG 0x28 should be 0x8100.  I have tried this on my setup and definitely see a change in the output as I am no longer seeing a byte-wise capture.  However, I suspect I have a problem with my bit-wise firmware as the capture is still not proper.  Can you check this on your design and confirm if you see a proper capture.

    Regards,

    Christian

  • Hi, Christian

            Thanks very much for the information. I wrote 0x8100 to Reg 0x28, and then the bit wise mode can be seen in the readout interface. 

    Regards, Weibin

  • Hi,

    I think you are set but could you confirm that you are able to capture a bit-wise signal as described in Figures 47 and 48 of the datasheet?

    Also, regarding the read back of some registers and not others, there are several registers that require the MSB be set to 1 in order to read back that register.  As you and I observed, Register 0x28 is one them.  We will update the datasheet with this information also.

    Regards,

    Christian

  • Hi, I've seen the bit-wise signal as described in the datasheet, and it works quite well. 

    Regards, Weibin