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CDCE72010: ADS5562EVM (SPI reprogramming)

NP
Prodigy 150 points

Part Number: CDCE72010

Hi,

I was wondering if this evaluation board allows reprogramming of the CDCE72010 chip? I generated SPI read commands (not write) to the different registers [0-12]  based on the IC datasheet but was getting return bits that don't correlate with the default register values as listed in the datasheet. And then I read in the user PDF that its been 'Factory Programmed' by TI.

Regards,

RW.

  • 0
    TI__Expert 4415 points
    Hi RW,

    Yes, it is possible to reprogram the CDCE72010 over SPI. The CDCE72010 on the EVM has been reprogrammed for the use case described in the EVM user's guide which is why the registers may not match the CDCE72010 datasheet default values.

    Regards,
    -Tim
  • 0 in reply to Tim Chao Li
    Prodigy 150 points
    Hi Tim,

    I'm thinking it might be my code - For testing, I'm currently trying to change only the divisor for the U1 register/channel. On page 25 (w/r/t Table 8), the configuration bits for implementing a divisor of 80 is (bit 6:0) 0011111. Thus,

    Write Command: 0xXX3EXXXX where X is don't care and 3E hex corresponds to bits 12-19.
    After sending in these bits, I then sent in the read register 1 command: 0x0000001E
    and was expecting to see '3E' on my probe. But this wasn't the case.

    Any recommendations or have I interpreted the datasheet incorrectly? Thank you.
  • 0 in reply to NP
    Prodigy 150 points
    My SPI protocol is set up to the following:
    LE switches from HIGH-LOW-HIGH....write register command MOSI
    wait..
    then LE is pulled from HIGH-LOW-HIGH (ie send read command MOSI) followed by
    LE going from HIGH-LOW-HIGH (read MISO)

    Speed: < 1MHz
    Command stream: 32-bits (28-data and 4-address)
    LSB transmission
    Data is send out and read in on the rising clock edge
  • 0 in reply to NP
    TI__Expert 4415 points
    Hi RW,

    Apologies for the delay. I'm not sure what the issue here is, as your setup appears to be correct. Your interpretation of the datasheet is correct as well. I would first verify that the SPI communication is working. One way to check this would be to read back the registers and make sure they match the expected default programming per Figure 4 on page 13 of the EVM user's guide: www.ti.com/.../slwu061a.pdf

    For example, you could check that the read back divider values are equal to the expected values.

    Regards,
    -Tim
  • 0 in reply to Tim Chao Li
    Prodigy 150 points
    Hi Tim,

    Resolved. It was the SPI - off by one bit. :S. After that, I was able to match most of the default register values as well as the 'divide by 4' in register 1. Thank you.

    Regards,
    Ron.