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CC1200 and GDO Pin for PA/LNA Control

Stephen Capelli
Prodigy 210 points
Other Parts Discussed in Thread: CC1190, CC1200, CC1125

Hi,

Seems I'm very confused by the user's guide for CC120x on application for PA/LNA Control.

I want to dedicate two IO for PA/LNA Control (CC1190)

IOCFGx shall be set to 0x24 (LNA_PD) and 0x25 (PA_PD)

From what I understand, _PD stands for _PowerDown.

The signal is active low ==> I would have understood that PowerDown is active low, but from my reading on the forum, it seems to be the exact opposite:

On PA_PD, a pulse low is applied when a frame is sent (TX). Is that Correct?

My issue is that for low power consumption reasons, i need to be sure of my config

Name        Reset  state                                  Sleep State           Idle (PA_PD cfg+ INV)           TX (PA_PD cfg+INV)              RX   (PA_PD cfg+INV)     

GPIO0       0    (EXT_OSC_EN = 0)              0 (or Hi-Z?)           0 (or Hi-Z?)                              1                                                0

GPIO2       0    (PKT_CRC_OK = 0)             0 (or Hi-Z?)           0 (or Hi-Z?)                              1                                                0

GPIO3       0    (PKT_SYNC_RXTX = 0)       1                             0                                                1                                                0

If I can only use one IO for RX/TX switch, which one shall I use?

Thanks.

BR

  • 0
    TI__Guru* 86241 points

    The signal is low during active state meaning that LNA_PD is low in RX and PA_PD is low in TX.

    The table below show how the different GPIOs will behave in different states when configured as either PA_PD or LNA_PD.

     

    PA_PD

    LNA_PD

    SLEEP

    IDLE

    RX

    TX

    SLEEP

    IDLE

    RX

    TX

    GPIO0 and GPIO2:

    0

    1

    1

    0

    0

    1

    0

    1

    GPIO3 :

    1

    1

    1

    0

    1

    1

    0

    1

     BR

    Siri

  • 0 in reply to Siri
    Prodigy 210 points

    Ok,

    So, since CC1190 needs inversed logic (PA_EN=1 to activate PA) , that would give:

     

    PD (INV )

    PD (NOT INV)

    RESET

    SLEEP

    IDLE

    RX

    TX

    RESET

    SLEEP

    IDLE

    RX

    TX

    GPIO0 and GPIO2: LNA_PD

    0

    0

    1

    1

    0

    0

    0

    1

    0

    1

    GPIO3 : PA_PD

    0

    0

    0

    0

    1

    		 0 1 1 1 0

    This would mean that LNA would be activated either in IDLE mode.

    SInce Idle mode shall only be a transition state that could fit...but if I need to improve consumption...

    If I only use on IO for RX or TX, shall i use RX0TX1_CFG?

  • 0 in reply to Stephen Capelli
    Prodigy 210 points

    Hi,

    I changed my solution into this by using LNA_PD cfg and RX0TX1_CFG.

    Could you please confirm me that this could fit?

    Since I have no information about state machine, I needed to be sure that this would fit, including delay for CC1190 turnaround.

    With this, LNA would be activated by LNA_PD

    PA_EN would be activated by RX0TX1_CFG.   (si RX0TX1_CFG a good fit to replace PA_PD?)

    I aim to use PA_RAMPING and Auto ack.

    Solution Register Valie Description Invert RESET SLEEP IDLE RX TX
    GDIO2 RX0TX1_CFG (0x26) Indicates whether RF operation is in RX or TX (this signal is 0 in IDLE No 0 0 0 0 1
    GDIO3 LNA_PD (0x25) Control external PA4 Yes 0 0 0 1 0
  • 0 in reply to Stephen Capelli
    TI__Guru* 86241 points

    Hi

    From what I can see, your solution seems to be good. I would, however, recommend you to do a test using a scope or logic analyzer and then output the signals while running some test code issuing the different strobe commands (SPWD, SRX, and STX) to verify that the timing of the RX0TX1_CFG signal is similar to that of the LNA_PD signal.

    BR

    Siri

  • 0 in reply to Siri
    Prodigy 210 points

    Hi,

    Thanks, but finally we'll use PA_PD with external logic, and external enable from µC.

    BR,

  • 0 in reply to Stephen Capelli
    Genius 5820 points

    I am also looking for a solution to control CC1190 PA/LNA pins from CC1200 GPIO's. Can you confirm that your last posted solution end up working well? 

    There are a lot of app notes showing use of CC1190 with CC1200 or CC1125 but none of them is clear on the GPIO configuration to control PA/LNA. Can someone from Ti please confirm the recommended pin configuration and circuit? 

    Thank you.

  • 0 in reply to pixbroker
    TI__Guru**** 317180 points
    - If your system doesn't need to be in SLEEP you can use LNA_PD/ PA_PD as the tables in this thread shows. These signals are also possible to use in SLEEP if GPIO3 is used, from the UserGuide:
    "This signal is active low. To control an external LNA, PA, or RX/TX switch in applications where the
    SLEEP state is used it is therefore recommended to map this signal to GDO3 as this signal will be
    hardwired to 1(0) in the SLEEP state."
    - If your system needs to be in SLEEP I would use the MCU to set the control line either indirectly by setting the GPIOs to '1' or '0' low using the HW0 or directly using IOs on the MCU. Typically the MCU "knows" if the system is in Rx, Tx or SLEEP.