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System Integration of TI MSP430F5438A, TI CC1101, and TI CC1190

Tyler Covington
Prodigy 90 points
Other Parts Discussed in Thread: CC1101, MSP430F5438A, CC1190

Howdy,

I am a student at Texas A&M University currently trying to develop a communications board which successfully implements a TI MSP430F5438A, TI CC1101, and a TI CC1190 for data communications. This system will include embedded intelligence which stores incoming data to the MSP430 and transmits the data between a matching 915 MHz network using the TI CC tranceiver chips. 

We have however encountered a small hardware problem which may have a fairly simple solution. The Current Hardware Design is based off of the datasheets for both the TI CC1101 and the TI CC1190. I have included the application circuits I am using below. 

Additionally, the CC1101, CC190 Schematic () that accompanies the TI CC1190 has been used in the development of hardware.This schematic proved useful as it depicts a CC1101 interfacing with a CC1190. In the datasheets of both devices, the enables which determine the state of the CC1190 seem to have simple connections back to the microcontroller but is a little bit unspecific. The Given schematic is done using an external microcontroller which connects to the on board CC1101 and CC1190 using a series of connectors or header pins and seems to be a much more complex connection. This schematic is shown below. 

In the Segment of the Schematic Below which we have put together, you can see the Connections of the CC1101 and the first half of the communications schematic. 

In this Schematic, The tags correspond to an actual connection being made to the MSP430. The pins are being used as follows. 

CC1101 CS P3_0
CC1101 MOSI P3_1
CC1101 MISO P3_2
CC1101 SCLK P3_3
CC1101 GPIO2 P2_5
CC1101 GPIO1 P2_6

In this segment of the Schematic you can see the problem that we are currently encountering. This is the configuration of our current alpha prototype which is being debugged and tested. We are currently exploring options on how to make this configuration operational. 

My question is, that in interfacing from these two devices back to an on board MSP430F5438A, what is the proper approach in connecting the devices? And is it possible to salvage and test the Current Configuration? Additionally, are there any other noticable issues with the design?

Thank you Very Much,

Tyler

  • 0
    TI__Guru**** 317180 points
    The CC1101+CC1190 is a reference design leaving open different options to set the control pins on CC1190. For evaluation it's easy to use the CC1101 set the state of the CC1190 but in a final system it would be more practical to have the MSP set the state of CC1190.

    For the first phases of debugging I would have used two wires to hard wire the LNA_PD/ PA_PD on the board to either the Tx or Rx state to check one way communication and then strap the LNA_PD/ PA_PD to the MSP later on.
  • 0 in reply to TER
    Prodigy 90 points
    Howdy,

    Thanks for the input on the use of lines to set the state of the TI CC1190.

    We have moved past this but have discovered a problem at the output of the TI CC1101 transceiver chip. Currently, when the coding is applied to the testing board, SPI communication is successfully made between the MSP430 and the TI CC1101. However, upon measuring the output of the SAW filter no signal is seen. Additionally while measuring the signal entering the SAW filter little to no signal is seen, the only measurable signal comes across at 8 Hz.

    In our application, an RF output of 915 MHz is expected which is far from the signal received.

    Any input as to possible hardware or software problems would be greatly appreciated.

    Thanks,
    Tyler
  • 0 in reply to Tyler Covington
    TI__Guru**** 317180 points
    Try to remove the SAW filter and check if CC1101 gives the expected output. Try first to do it very simple, send a CW (tone) @915 MHz. If you don't see a signal at the expected frequency, check that the chip state is TX, do you have 1.25 V at the R_BIAS pin. If you have one, try to control the CC1101 with CCDebugger to rule out software issues.
  • 0 in reply to TER
    Prodigy 90 points

    I do not currently have 1.25V at R_BIAS, rather there is a 56k resistor connected to ground. Would a 1.25V input on that line be a viable change for the next revision of the hardware? Also is there any other way to easily rule out software issues?

    Thank you so much for your help,

    Tyler

  • 0 in reply to Tyler Covington
    TI__Guru**** 317180 points

    I think I was unclear: Do you measure 1.25 V on the R_Bias pin? If the chip is on this is the expected voltage here.

    The easy way to rule out software is to use SmartRF Studio and a CCDebugger.

  • 0 in reply to TER
    Prodigy 90 points

    Thank you for all of your  help.

    Currently No voltage is received on the R_Bias pin although the transceiver chip has 2.75V on all inputs. 

    Additionally, both ground pins are successfully connected to ground. 

    I cannot help but wonder if this issue is related to the die attach pad which must also connect to ground. Currently a ground trace runs to this pad, is this the correct implementation of the design?

    The current PCB design with the power and ground lines can be seen below. 

    -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Thanks again for any and all input,

    Tyler