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ADS122U04: Unable do communicate with the chip

Abderrahman HILALI
Prodigy 20 points

Part Number: ADS122U04

Dear all,

Its my first experience with this componnent, i can not communicate with it (from my PC). Please could someone help or send a procedure for first steps in using of this product (which software, commands, ...)

Thansk All

  • 0
    TI__Guru** 113765 points
    Hi Abderrahman,

    Welcome to the E2E forum! You may be very familiar with your setup and what you are attempting, but I know very little and can only make some guesses. The ADS122U04 is not designed to connect directly to a PC and requires some sort of interface so that the voltage levels and communication are matched between devices. The ADS122U04EVM, for example, uses a microcontroller with a USB interface as a bridge to communicate to the PC using a USB virtual COM port. Command and responses can be sent via a COM terminal program on the PC.

    Can you give me more detail with schematics, wiring, pictures, etc. of how you are connecting things together?

    I think the best place to start is to review the ADS122U04 datasheet for the required communication needed to talk to the device. I would also suggest that you use an oscilloscope, or better yet a logic analyzer that can decode the communication protocol to monitor the communication. All communication to the ADS122U04 must begin with a synchronization word 0x55. Also, you cannot send and receive at the same time as the ADS122U04 is not a full-duplex device. Also pay attention to all voltage levels you are using. PC's with a dedicated COM port use voltage levels (RS232) that are outside of the voltage range of the ADS122U04.

    Best regards,
    Bob B
  • 0 in reply to Bob Benjamin
    Prodigy 10 points

    Hi bob,

    I work with Abderrahman and we are trying to make a tensile forces sensor. 

    As for now, we have made a resistive bridge (Wheatstone half bridge with 2 strain gauges) to measure the strain , and we want to amplify and convert the output of the bridge. The ADS122U04 appears to be appropriate for the project. 

    We are using the schematics from the ADS122u04 datasheet :

    I am not familiar with the communication protocol and the equipment requiered (but i understand how serial communication works) . We only have a small UART-to-USB converter and the HyperTerminal Software to send and receive datas.

    If i understand we have to use an interface to communicate with the ADS122U04 from a PC. Can we do it with the converter (see bellow) or do we need an interface like the one you suggest? 

    Converter CP2102 USB-UART :



    Do you have any other suggestions or advices concerning the project/schematic ?

    Best regards,


    Allan FONTAINE

  • 0 in reply to Allan Fontaine
    TI__Guru** 113765 points

    Hi Allan,

    The USB-to-Serial converter you show should be ok to use for communication.  Make sure that the operating voltage your are using for the converter and the ADS122U04 are the same.  As the ADS122U04 only has TX and RX signals, I'm not sure how the converter will respond if the DTR and CTS signals are not connected to the proper voltages for communication.  I would suggest using an oscilloscope or logic analyzer to verify communication sent between the PC and the ADS122U04.

    Make sure that TX from the converter goes to the RX of the ADS122U04, and TX from the ADS122U04 goes to the RX of the converter.

    From the terminal you need to send the data as the correct value.  For example, the synchronization word is 0x55.  You would not type into the console 0x55 as the ASCII values are transmitted.  What would be sent mistakenly in this case is decimal 48 120 53 53.  The hex value for 0x55 would be the ASCII equivalent for U.  Not all characters are printable, such as a 0x00 (ASCII NULL) or 0x09 (ASCII TAB).  You also need to be careful with CR and LF.  The ADS122U04 will not send an echo.  So there is a bit of a challenge when it comes to sending/receiving data.  You may want to look into something like Tera Term instead of Hyperterminal which allows you to create hot key command strings.

    There was another post similar to yours a while back with a little more information.  I'm not sure if that person was ever really able to communicate properly through a terminal.

    https://e2e.ti.com/support/data-converters/f/73/t/739398

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 20 points

    Hello Bob,

    thank you for your help

    We will come back to you one we complete the job and close this post.

    Tanks