1 Reply Latest reply on Oct 29, 2015 2:25 PM by MichaelF_56 Branched from an earlier discussion.

    Using internal 128kHZ Oscillator vs. external oscillator

      Per this thread: Re: clock reference/RTC during deep sleep?


      We do not have an external 32kHz crystal on our board.  Is there a simple example of how to setup the rtc_sample application to run off of the internal 128kHz oscillator?  What simple modifications are required?


      Thanks in advance,


        • 1. Re: Using internal 128kHZ Oscillator vs. external oscillator



          I'm pretty sure that the rtc_sample in the SDK covers both the on-chip RTC and the external 32 KHz LPO.


          * RTC Sample


          * This application provides the sample code for interfacing with

          * the on-chip RTC clock. It is highly recommended that an external 32K

          * xtal be used when accurate time is to be maintained. The accuracy

          * of the time maintained with the an external LPO is an order of magnitude

          * better than the internal LPO.



          * Features demonstrated

          *  - Use of the on-chip RTC interface.

          *  - Use of the external 32 KHz LPO for sleep and deep sleep.

          *  - Entering deep sleep on demand.

          *  - Using the external LPO (32KHz xtal) for timed wake from deep sleep.


          * To demonstrate the app, work through the following steps.

          * 0. Enable the external 32KHz oscillator on the TAG board (see Quick Start Guide -

          *    make sure that R102 and R103 on BCM920737TAG_Q32 are populated

          *    with a 0 Ohm resistor, else the the behavior is undefined).

          * 1. Plug the WICED eval board into your computer

          * 2. Build and download the application (to the WICED board)

          * 3. Application initializes and RTC and prints time every second.

          * 3.a Application programs and enters deepsleep, optionally configuring for a timed wake.