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BOOSTXL-CC1120-90: CC1120EM-868-915-RD

PAVANAKUMAR A G
Prodigy 60 points
Part Number: BOOSTXL-CC1120-90
Other Parts Discussed in Thread: CC1120, CC1190

Tool/software:

Hi all,

I'm working on a project using CC1120 in combination with the CC1190 RF front-end module. I need to both transmit and receive data via RF. To control the front-end:

  • During transmission, I enable PA and disable LNA.
  • During reception, I enable LNA and disable PA.

I control the PA and LNA through external GPIOs (from my MCU, not CC1120 GPIOs).

Issue:

If I switch PA/LNA control logic directly between TX and RX, RF communication does not work reliably. However, if I insert a delay (e.g., 200 ms) between switching from TX to RX (or vice versa), it works properly.

My Question:

Is there any configuration or timing constraint related to CC1120 or CC1190 that I should consider to reduce the switching time between transmission and reception?

Is this delay due to:

  • Settling time in CC1190’s internal circuitry?
  • Timing requirement for RF path stabilization?
  • CC1120 state transition delays?

I would appreciate any suggestions to improve the reliability of TX/RX switching without adding large delays.

Thank you!

  • 0
    Mastermind 6360 points
    PAVANAKUMAR A G said:
    If I switch PA/LNA control logic directly between TX and RX

    Exactly when do you set the IOs controlling PA/ LNA? Or to ask a bit differently, how do you determine that TX or RX is done to change the GPIO?

  • 0 in reply to TheGhostOf
    Prodigy 60 points

    Thank you for the replay,

    After calling the STX command I am checking the state of the CC1120 if it is idel then I am switching the mode from TX to RX.

  • 0 in reply to PAVANAKUMAR A G
    Mastermind 6360 points

    I guess you have two CC1120 + CC1190 modules where they switch between RX and TX? How do you switch from RX to TX on the other side of the link? 

  • 0 in reply to TheGhostOf
    Prodigy 60 points

    I have two sets of CC1120+CC1190 modules I need to transmission and reception between two boards, In both the boards after transmission completion, I disable PA and enable LNA in both the boards

  • 0 in reply to PAVANAKUMAR A G
    TI__Mastermind 23219 points

    Hi Pavanakumar,

    You definitely have to add a delay, and the PA needs some ramp up time.

    Regards.

    Arthur

  • 0 in reply to Arthur R☑️
    Prodigy 60 points

    It is mentioned in the CC1190 datasheet that 600ns but it is working for only 200ms delay after the transmission

  • 0 in reply to PAVANAKUMAR A G
    TI__Mastermind 23219 points

    Hi Pavanakumar,

    Can you post the register settings that you are using on the CC1190?

    Regards,

    Arthur

  • 0 in reply to Arthur R☑️
    Prodigy 60 points

    {IOCFG3, 0x02},

    {IOCFG2, 0x00},

    {IOCFG1, 0xB0},

    {IOCFG0, 0x73},

    {SYNC3, 0x8F},

    {SYNC2, 0x9F},

    {SYNC1, 0x7F},

    {SYNC0, 0x9F},

    {SYNC_CFG1, 0x0B},

    {SYNC_CFG0, 0x14},

    {DEVIATION_M, 0x48},

    {MODCFG_DEV_E, 0x0B},

    {DCFILT_CFG, 0x15},

    {PREAMBLE_CFG1, 0x18},

    {FREQ_IF_CFG, 0x3A},

    {IQIC, 0x00},

    {CHAN_BW, 0x14},

    {MDMCFG0, 0x05},

    {SYMBOL_RATE2, 0x63},

    {SYMBOL_RATE1, 0xA9},

    {SYMBOL_RATE0, 0x2A},

    {AGC_REF, 0x24},

    {AGC_CS_THR, 0xEF},

    {AGC_CFG1, 0xA9},

    {AGC_CFG0, 0xC0},

    {FIFO_CFG, 0x00},

    {SETTLING_CFG, 0x0B},

    {DEV_ADDR, 0x43},

    {FS_CFG, 0x12},

    {PKT_CFG2, 0x04},

    {PKT_CFG1, 0x15},

    {PKT_CFG0, 0x20},

    {PA_CFG2, 0x77},

    {PA_CFG1, 0x56},

    {PA_CFG0, 0x7E},

    {PKT_LEN, 0xFF},

    {IF_MIX_CFG, 0x00},

    {FREQOFF_CFG, 0x20},

    {FREQ2, 0x6C}, //Frequency is set to 866Mhz

    {FREQ1, 0x40},

    {FREQ0, 0x00},

    {FS_DIG1, 0x00},

    {FS_DIG0, 0x5F},

    {FS_CAL1, 0x40},

    {FS_CAL0, 0x0E},

    {FS_DIVTWO, 0x03},

    {FS_DSM0, 0x33},

    {FS_DVC0, 0x17},

    {FS_PFD, 0x50},

    {FS_PRE, 0x6E},

    {FS_REG_DIV_CML, 0x14},

    {FS_SPARE, 0xAC},

    {FS_VCO0, 0xB4},

    {XOSC5, 0x0E},

    {XOSC1, 0x03},

    {RFEND_CFG1, 0x3F},

    {RFEND_CFG0, 0x30},

    {FIFO_CFG, 0x66},

  • 0 in reply to PAVANAKUMAR A G
    TI__Mastermind 23219 points
    PAVANAKUMAR A G said:
    I control the PA and LNA through external GPIOs (from my MCU, not CC1120 GPIOs).

    Although you do not use the CC1120 GPIOS to control the PA, do you have the possibility to enable thoses, just to see how the CC1120 triggers them in relation to your own MCU control pins?

    As of reducing the time to switch between RX, and TX, have you had a look at the TXOFF_MODE and RXOFF_MODE settings?

    Regards,

    Arthur

  • 0 in reply to Arthur R☑️
    Prodigy 60 points

    In CC1120, how do the TXOFF_MODE and RXOFF_MODE settings determine the mode the device enters after transmission or reception? Should it stay in TX mode or switch to RX mode?, But my doubt is how much time i need to enable PA for transmission and how much time i need to enable LNA for reception.

  • 0 in reply to PAVANAKUMAR A G
    TI__Mastermind 23219 points

    Hi Pavanakumar,

    Those settings are detailed in the user guide, so according to what you want to do, you can certainly configure them.

    On the other question, looking at the CC1120 PA/LNA GPIO pin would certainly help in knowing how long you would need to leave the PA and LNA in ON state.

    Regards,

    Arthur