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TRF3765 SPI COMMUNICATION

Mariana Galmarini
Prodigy 120 points
Other Parts Discussed in Thread: TRF3765

We have implement the SPI communication with PIC (16F876A)  in order to send the corresponding signals to the TRF3765 (CLOCK, DATA, STROBE) but the TRF did not read the signals.

We think the signals are fine, we have checked this with an digital oscilloscope.

Someone has implemented the SPI communication in other way and can help us to do this.

We will appreciate your help.

Best regards,

Mariana.

  • 0
    TI__Expert 3300 points

    You might consider downloading the TRF3765 GUI from ti.com. Then you would be able to compare known-good waveforms against your own waveforms by monitoring EVM testpoints. Note that the EVM communication uses USB signals routed through an FTDI device, so the SPI (4WI) signals can only be viewed after the FTDI device.

  • 0 in reply to Pete Hanish
    Prodigy 120 points

    Peter,

    Thank you for your answer.

    Where we can find the TRF3765 GUI?

    Some more question:

    When we send the SPI signals is necessary supply all VCC pins?

    Is necessary do something else before send the SPI signals to the TRF?

    Do you have an example of a code to program a microprocessor (like PIC)  which send SPI signals?

    Because we would like to compare the code which we compile to the PIC with other example.

    Thank you.

  • 0 in reply to Mariana Galmarini
    TI__Expert 3300 points

    On ti.com, search for the TRF3765 EVM. The GUI is available on the product page under the Software heading.

    Only VCC_DIG is required to access the 4WI (SPI) registers. However, it may be useful to power other supplies to monitor operation of the device.

    Once power is applied to the device, it is able to receive writes to the registers. Nothing special needs to happen before the device receives commands. If the timing and sequences specified in the datasheet are observed, there are no other known requirements. Oscilloscope waveforms have been posted for reference previously in this forum at http://e2e.ti.com/support/rf__digital_radio/high_performance_rf_modulators_pll_and_vco_products/f/224/t/212323.aspx. 

    TI's TRF3765 GUI was developed in LabVIEW.

  • 0 in reply to Mariana Galmarini
    Prodigy 30 points
    I don't understand why this device does not use a standard SPI bus format.
    Since it does not I have to reinvent the wheel and write code to generate this frame format with GPIO pins from my cpu.
    Is there any example of this anywhere?
  • 0 in reply to D Snyder
    TI__Mastermind 18095 points

    The best example for the TRF3765 is the programming GUI available on ti.com.  The device follows the standard 4-wire interface for SPI communication.  The register mapping as seen in the datasheet (4 address bits, 28 data bits) may be deemed non-standard.  In general you are free to clock in the data through any means at your disposal (i.e. uP, LabVIEW, CPLD, etc.).

    --Russell

  • 0 in reply to RJ Hopper
    Prodigy 30 points
    For my application I need to use the spi bus from a TM4C1294 cpu to program the TRF3765 through the 4WI interface.
    The GUI doesn't help me with this. I would like to use one of the TM4C1294 QSSI interfaces to do this. However
    these standard SPI bus interfaces are 4-16 bits in length, and the TRF3765 requires 32 bit frames, which does not
    appear to be possible with the QSSI interface. What I am looking for is an application with source code that has
    done this.
  • 0 in reply to D Snyder
    TI__Mastermind 18095 points

    Ah, I understand.  I have not used the TM4C1294 for programming.  It seems like it would be possible to use two 16-bit words to generate one register write.  Obviously, the key is to toggle the LE at the appropriate time.  Perhaps the support team for the TM4C1294 can offer some suggestions to program a 32-bit register.

    --RJH