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CC3230SF: File System Access Without Wi-Fi Radio Transmission

Hamza Imtiaz
Prodigy 170 points
Part Number: CC3230SF


Tool/software:

Hi All,

I am using the CC3230SF and need to access the serial flash file system to update my application's configuration. My device is already connected to an LTE modem, so I must ensure the Wi-Fi radio does not transmit any RF signals.

I understand that the Network Processor (NWP) needs to be started to access the flash. If I use sl_WlanPolicySet(SL_WLAN_POLICY_PM, SL_WLAN_LOW_POWER_POLICY, NULL,0) followed by sl_Start(0,0,0), will this start the NWP and allow for file system access without the Wi-Fi radio transmitting any beacons, probe requests, or other signals in either Station or Access Point mode?

I only need the NWP to be active for its file system management capabilities, not for Wi-Fi communication.

Thanks

  • 0
    TI__Intellectual 2090 points

    Hi Hamza,

    I'll get back to you on this after the weekend, Tuesday latest.

    Thanks.

  • 0 in reply to BLiu
    Prodigy 170 points

    Hi ,

    Any update?

  • 0 in reply to Hamza Imtiaz
    TI__Intellectual 2090 points

    Hi Hamza,

    Thank you for your patience. 

    For the power save policy, please ensure that your device is not an access point. Power saving modes do not work for access points, so your device needs to be configured as a station. 

    When a device utilizes power save mode, if your device is already connected to an access point, it will stay connected, but the radio turns off and the access point that your device is connected to will know not to send anything to your device until your device wakes up. You can see the network processor manual for more information; pages 234 - 235 are helpful. 

    However, I need to verify that what you are doing falls under the power save mode policy which disables the radio (and stays connected to the AP it already connected to) but does not get into LPDS or hibernation because you cannot interact with the file system during those states. That way, you don't have to explicitly disable scanning, connection policies, and provisioning. 

  • 0 in reply to BLiu
    Prodigy 170 points

    Hi Brandon,

    Thank you for the explanation. I understand the difference between AP vs STA with respect to the power policy, and that LPDS/hibernation prevents file system access.

    However, my original concern is still not fully clear: if I start the NWP in STA mode with sl_WlanPolicySet(SL_POLICY_PM, SL_WLAN_LOW_POWER_POLICY, NULL, 0) and then call sl_Start(), will the NWP remain available for file system access without transmitting any RF activity at all (no beacons, probe requests, or scans)?

    Thanks again for your help,
    Hamza

  • 0 in reply to Hamza Imtiaz
    TI__Intellectual 2090 points

    Hi Hamza,

    Only access points use beacons. Stations use probe requests. 

    SL_WLAN_LOW_POWER_POLICY is one of multiple power policies you can set for your device. This application note describes some other power policies as well on page 9. All of them, including low power and normal mode, essentially program the network processor to determine when to turn on and turn off the radio. The radio turns back on at intervals specified by those power policies, and yes, even with the radio off, you can still access the file system because the network processor itself can be on even if the radio is off (see the block diagram in this TRM on page 62). 

    When you use SL_WLAN_LOW_POWER_POLICY, the networking subsystem goes into LPDS and on every DTIM (see this E2E for explanation on such intervals) will wake up. If this is what you want, you can still wake up the network processor from LPDS to do file system access even when the radio is off, if that is what you want with the other features I mentioned. I will say that the low power policy (as seen on page 9 of the application note) is generally used for tag application, so hopefully that kind of scenario fits your use case.

    I hope this helps.