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Original question:

PGA 309 TIPD126 reference board kit programming

TIPD126: Connection problem with TIPD126

Henrik Kjellberg
Prodigy 20 points
Part Number: TIPD126
Other Parts Discussed in Thread: PGA309EVM-USB, , XTR117, PGA309

I have my PGA309EVM-USB board working and I can use it to measure a physical sensor and send it to current loop, but now I'm trying to move the setup over to the TIPD126 board and nothing happens. It's like the 1W is not responding? I have verified the pinouts for 1W, GND, XTR+ and XTR- and the internal Vref voltage from the XTR117 on my board. Reading the registers returns only zero's. Any tips on how to proceed with debugging?

BR.

Henrik

  • 0
    TI__Guru 53446 points

    Hi Henrik,

    One potential issue that comes to mind, which is a often a challenge on 4-20mA two-wire current transmitters, the local transmitter ground (IRET pin of the XTR117) which is the same GND potential of the 1-W interface, must be allowed to float with respect to the Loop supply GND.  In other words, the GND supply of the 4-20mA current can not be connected to the 1-W interface GND.  Can you please confirm that the 1-W GND connection is not connected to the 4-20mA loop supply (LOOP- ) GND?

    The TIPD126 is a reference design developed on 2013 (not an evaluation board in production) and I don't have immediate access to this PCB. However, I have a similar internal engineering module involving the PGA309 and XTR117 that I could use to connect to the USB-DAQ and attempt to reproduce the issue.

    Can you please provide a detailed description or diagram showing the current loop supply connections, the 1-W interface and GND connections made between the TIPD126 PCB board and the USBDAQ controller?  This may allow us to help debug the issue.  

    Thank you,

    Kind Regards,

    Luis

      

  • 0 in reply to Luis Chioye
    Prodigy 20 points

    Hi Luis,

    Thank you for the input. I just verified that the current loop negative is not connected to system GND, so unfortunately that's not it. The TIPD126-board is connected to the USB DAQ Platform through the DAQ-board connector J3 (1W on pin 11 and 21, current loop on pin 14 and 15) the same way as the evaluation board as far as I can see. 

  • 0 in reply to Henrik Kjellberg
    Prodigy 20 points

    I finally got my analyzer up and it seems to be some issue with the i2C communication with the external EEPROM. Further investigation is ongoing.

  • 0 in reply to Henrik Kjellberg
    Prodigy 20 points

    Ok, problem solved! Or rather identified... The proposed 16kbit EEPROM was not available, so I selected another 16kbit i2c EEPROM in SOT23-5. Unfortunately they differs in one important part: The proposed one has three bits block address where the one I picked has three bits of device address. The one I got requires two bytes of address while the proposed one only takes one byte address (and combines it with the block address). In other words, they are not compatible.

    I'll just have to pick up some new EEPROM's and grab the iron! Nerd Writing hand

  • 0 in reply to Henrik Kjellberg
    TI__Guru 53446 points

    That's good news.  Thank you for letting us know how the issue was resolved. This information is always useful for future reference.

    Thank you and Kind Regards, 

    Luis