6 Replies Latest reply on Feb 15, 2014 9:33 PM by MuOr_1658816

    WICED WiFi Battery Operation

    MuOr_1658816

      I am working on a battery powered WiFi device. By using the functions below, I assume the device will save as much power as possible.

       

      Low Power:

      wiced_platform_mcu_enable_powersave();

      wiced_wifi_enable_powersave();

      wiced_network_suspend();

       

      Resume Operation:

      wiced_network_resume();

       

      With this, how can I calculate how much current the device will theoretically use over time?

        • 1. Re: WICED WiFi Battery Operation

          The SDK comes with a snippet app called ping_powersave that demonstrates doing periodic Wi-Fi activity while minimizing power consumption between pings.

           

          What hardware platform do you have?

          Many WICED development platforms have a dedicated test point where you can hook up an oscilloscope to measure the current drawn by the Wi-Fi module (This includes the power of the host processor).

          By writing a test application and measuring the current usage you can approximately calculate how much energy your application will consume over a period of time.

          • 2. Re: WICED WiFi Battery Operation
            MuOr_1658816

            We are using BCM943362WCD4_EVB for development. I saw the example and the functions I mention is from that example.

             

            I want the module to go into power save mode for a minute, then wake up and do a similar ping. Where are the test points? I don't want to measure the FTDI parts draw.

            • 3. Re: WICED WiFi Battery Operation

              The schematic for the module and eval board are in the SDK-2.4.0/Doc/Schematics directory

              There are two test points on the eval board marked GND & CURRENT.

              Grab a scope and get busy!

              • 4. Re: WICED WiFi Battery Operation
                MuOr_1658816

                It is surprising to find out that the lowest it can go is 2.9mA. This is a very big current draw if you are operating on batteries.

                • 5. Re: WICED WiFi Battery Operation

                  Please read the Powersave application note shipped with the SDK.

                  It provides detailed information about measuring power.

                  The power measurement cct on the eval board is not designed to measure below a few mA.

                  The BCM43362 chip drops to ~200uA between beacons, you will need to add any MCU current consumption to this number however.

                  • 6. Re: WICED WiFi Battery Operation
                    MuOr_1658816

                    We are using Murata Type YD for production. Their report confirms what we are seeing on the scope. Will it be better to turn off WiFi between transmissions to save battery or if it takes too long to associate and get IP address, it will be better to stay connected.

                     

                    I have no doubt that the radio is pretty low power when idle, but I am surprised to see that the MCU is adding so much.