7 Replies Latest reply on Jul 16, 2019 7:53 AM by VictorZ_46

    BLE module in receive only mode

    SuKa_2620366

      Is it possible to turn off TX on a BLE module to save power, and enable Receive only? The module should wake up on a message received.

       

      Is it possible? Which module / chipset supports it?

       

      Thanks.

        • 1. Re: BLE module in receive only mode
          VictorZ_46

          SuKa_2620366

          TX is off until you try to send something.  RX is configured by the application.  For example, if your device is scanning for advertisement packets, you need to configure scan window/interval and start the scan.  Cypress chip do not support Wake on Radio feature.  Not sure how reasonable the feature is. Unlike NFC where this feature is extremely useful, it is hard to imagine an environment in this world where you do not receive a valid BLE packet within a second.

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          • 2. Re: BLE module in receive only mode
            SuKa_2620366

            This is a battery powered personal device, so they want to save every bit of power. Only one user's cellphone is paired with that device.

            If the cell phone is off/away, or the app is not running, then they want to keep all electronics on that device in sleep mode.

            When user opens app and tries to communicate with the device over BT, the device should Wake on Radio. Sleep mode should consume less than 10 me power is primary requirement.

            • 3. Re: BLE module in receive only mode
              VictorZ_46

              Not sure what 10 me power is.  Typically a device will run in peripheral mode, i.e. it is in the deep sleep, wakes up every so often, sends an advertisement, listens for a connect from a paired device, and goes backs to sleep. When application on a phone starts up, it will perform a scan, will see the advert and  will connect.  At the connection time, the BLE device can wake up the rest of the system.  I believe the power consumption with advertisements with around 1 sec interval which results in a reasonable connection latency is in order of 20uA.

               

              I guess it will be a better choice if there is a chip which wakes on receiving an advert from a specific device.  Please note that a phone uses Private Random Bluetooth device address.  That means that the wake up radio needs not only to detect a valid BLE packet, but be able to decrypt the address of the sender to find out that it is appropriate to wake up.  Otherwise your power consumption will greatly depend on the environment, i.e. how many BLE beacons are in the area.

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              • 4. Re: BLE module in receive only mode
                SuKa_2620366

                10me Its a typo. Less than 10mW power consumption in sleep mode is requirement.

                If I understand you correct, the Cypress module will wake up every second to scan, and the power consumption will still be below 10mW?

                 

                The feature I was looking for is 'Wake on Radio with frame detection'.

                 

                 

                • 5. Re: BLE module in receive only mode
                  VictorZ_46

                  No, what I wrote is that our low power design will wake device up once per second and will send an advertisement packet.  If nobody will connect, the device will go to sleep.  The power consumption is in order of 20uA (micro amps). If I understand it correctly with 3V power supply the consumption in mW is 20 / 1000 * 3 which is about 0.06mW. 

                   

                  If you are looking for a feature with the name "Wake on Radio with frame detection" we do not support it.

                  • 6. Re: BLE module in receive only mode
                    SuKa_2620366

                    Ok. I assume the 10uA power consumption is while module is sleeping.

                    What will be the current / power consumption of module when it wakes up, send advertisement packet, waits for response from phone and go back to sleep? Also what is the module number?

                     

                    Thanks.

                    • 7. Re: BLE module in receive only mode
                      VictorZ_46

                      Actually it was 20uA and it was the average power assuming which covers sleep, wake, send, listen. I might be off by a few uA, but it should be close. 

                       

                      Cypress ships several BT SoCs with different capabilities and different price tag.  You should be able to find info WICED Studio Bluetooth. Which one you need for your project will depend on what functionality you want to enable in addition to sleep.  If you do not need much more other than sleep and wake the host when a valid packet is received, you can probably use any chip. For example, https://www.cypress.com/documentation/datasheets/cybt-213043-02-ez-bt-module .