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Programming a CDCE949

Derek Day
Prodigy 70 points
Other Parts Discussed in Thread: CDCEL949, CDCE949, USB2ANY

I am trying to programme a CDCE949 using the CDCEL949 evaluation board.

I have 4k7 pull-ups on my board and have disconnected R55 and R56 on the evaluation board and disabled the level translator using J26.

I have connected the SDA and SCL outputs to my board but I can't programme the IC on the board.

I originally tried the system segested in the user guide for the evalaution board but that did not work, so since the voltages on the CDCEL949 are 1V8 I tried the above.

Any constructive suggestions welcom. Can you programme the CDCE949 via the USB2ANY? are there pods available that work better than the evaluation board approuch?

Regards

Derek

  • 0
    TI__Expert 5325 points
    Hello Derek,
    all devices of the CDCE9xx family (except CDCEx06) all have a 1.8V core and 1.8V or >2.5V output buffer supply.
    The serial interface pins are part of the 1.8V VDD supply. The microcontroller of the CDCE949 and CDCEL949 are the same.
    The performance EVM has a capacitor (C70) on SDA to tune the delay between SCL, SDA.
    Did you crosscheck the waveform at your receiving CDCE949 device?

    Do I understand correctly that you wired the SDA, SCL from the de-soldered R55,R56?

    Thanks!

    Best regards,
    Patrick
  • 0 in reply to Patrick Kammermayer
    Prodigy 70 points
    Hi Patrick

    Yes you are correct we are connecting the SCL and SDA to our device at the R55 and R56 end.
    We have removed R55 and R56 and removed J25 and added J26 to disable U21. the datasheet for the CDCE949 says the SDA and SCL lines can handle upto 3V6.
    We have pull-ups to 3V3 on our board hence the desire to connect at the at the U17 end of the SCL and SDA signals.
    On the oscilloscope the waveforms look a bit poor but if we use an external supply for the +5V by removing J23 then the waveforms look good.
    But the IC will still not programme.

    Please can you confirm that the I2C interface remains available after the device is programmed?
    Some information in the forums suggests that once programmed the I2C interface of the CDCE949 becomes inactive and requires the Vout pins to be grounded for the I2C serial interface to be available again.

    Regards

    Derek
  • 0 in reply to Derek Day
    TI__Expert 5325 points
    Hello Derek,
    that depends on which settings you saved into the EEPROM earlier.
    It is correct that the serial interface can be deactivated and the device being used in a "pin mode" where you can select from multiple profiles saved inside the EEPROM.

    The bit to deactivate the serial interface is "SPICON" which is Bit 6 of register 2. Please check footnote 6 of the register map table.

    When you should have accidentally used this feature: the only way to re-activate the serial interface is to tie the VDDOUT to GND while powering up VDD. Then you can modify the registers and EEPROM again.

    Best regards,
    Patrick