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TMS37157: Communication between TMS3705 and TMS37157

Gerd Christian Knese13
Intellectual 410 points
Part Number: TMS37157
Other Parts Discussed in Thread: TMS3705, , UCC27424, MSP430F6659, MSP430FR5739

,Hi,

I'm working on a design with TMS3705 and TMS37157.

The transmitter hardware with the TMS3705 is ready and needs to be programmed to do the job.

The transponder is on prototype level at the moment.

To code the software for the TMS3705, I need to understand how the communication between TMS3705 and TMS37157 works.

For this I use the eZ430-TMS37157 development tool.

The communication of the TMS3705 looks like this at the moment:

The blue line is TXCT, the red is SCIO, the green is the field (external sensor), the orange is the SENSE input of the TMS3705.

According to the datasheet of the TMS37157 it sends the answers via an FSK (134.7 and 123.7 kHz)

My question is, the TMS37157 is responding (red line second bit sequence), but I can't see the FSK response in the field or the SENSE input.

Where is it?

Kind regards

Gerd

  • 0
    TI__Guru*** 135355 points

    Hello Gerd,

    I am not an expert with these devices, so let me post our available collateral for you to review as a start. Any questions unclear after looking through these documents I'll provide please ask and I will circle back with others in the team who have the expertise to further explain.

    Since the eZ430-TMS37157 tool page is down, I am not sure if you have the following documents, so pardon if you already reviewed some of these:

    eZ430-TMS37157 Development Tool User's Guide: http://www.ti.com/lit/ug/slau281b/slau281b.pdf

    App Note for the base station included with eZ430-TMS37157: http://www.ti.com/lit/an/swra283/swra283.pdf

    Also I am not aware if you have our firmware offerings which you can reference, leverage, and even re-use if desired for this application:

    Firmware for Base Station (TMS3705): http://www.ti.com/litv/zip/slac350

    Firmware for Target Board (eZ430-TMS37157): http://www.ti.com/lit/zip/swrc165

    I am also attaching pdf with very deep technical details about this application from Josh Wyatt who used to support these devices (you may find searching E2E and reading his postings helpful): 2627.TMS37157 PaLFI_Technical_Training_03_29_2010.pdf

    I think when armed with this collateral, you should be able to move forward with your development, but as mentioned if you have issues with understanding the communication between the TMS3705 and TMS37157 please let me know.

  • 0 in reply to Ralph Jacobi
    Intellectual 410 points

    Hello Ralph,

    Thanks a lot for you extensive answer.

    Especially the presentation from Josh Wyatt was very enlightening for me.

    There is just one question not answered in his presentation.

    It looks to me, that in his examples the TMS3705 was set into synchronous mode.

    According to the datasheet, this could be done via MCR write.

    Unfortunately this is not part of the presentation, as far as I could see.

    I try to do this, but even if I send MCR code 0x20 to TMS3705 nothing changes.

    Any Idea why?

    Kind regards

    Gerd 

  • 0 in reply to Gerd Christian Knese13
    Intellectual 410 points

    Hello Ralph,

    Please do me a favour and forget the last post.

    I misunderstood something in Josh Wyatt presentation.

    But, please allow one more question.

    My design is:

    Transmitter: MSP430F6659 with TMS3705 plus UCC27424

    Transponder: TMS37157 with MSP430FR5739 connected via SPI interface.

    I want to transmit a simple sequence of numbers from the MSP430F6659 to the MSP430FR5739.

    Is there maybe a source code example available, I can modify to find a starting point?

    I hope for your help with this.

    Kind regards

    Gerd

  • 0 in reply to Gerd Christian Knese13
    TI__Guru*** 135355 points
    Hello Gerd,

    Unfortunately the two firmware links I provided in my prior post is all that we offer. You would need to port that firmware to your respective devices.

    I did notice I shared one bad link, which was supposed to be:

    Firmware for Target Board (eZ430-TMS37157): www.ti.com/.../swrc165
  • 0 in reply to Ralph Jacobi
    Intellectual 410 points

    Hello Ralph,

    Thanks a lot for your help. The discussion with you finally set me on course to find the solution.

    Kind regards

    Gerd