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WICED Smart Bluetooth

Anonymous
Not applicable

Does 20732 chip need a external 32.768 crystal? I had thought the 32.768KHZ crystal is used for advertising when chip in sleep mode, but it seems not, when I take out the crystal, it can still enter into sleep mode normally, then  what on earth this crystal used for?

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BoonT_56
Employee

The ext 32k crystal is really optional. However there are some differences in configuring the wake up time after a prescribed interval. The details are in here: Sleep Deep_Sleep Explanation and Techniques

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BoonT_56
Employee

The ext 32k crystal is really optional. However there are some differences in configuring the wake up time after a prescribed interval. The details are in here: Sleep Deep_Sleep Explanation and Techniques

View solution in original post

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Anonymous
Not applicable

Thanks Boont and J.t for the very detailed explain.

I still have a question, I added an external 32.768kHZ crystal in the design, but cannot measure the clock out from the crystal at all, that means the external crystal don’t work at all, should I make some configuration to make it enable and stop using the internal 128KHZ LPO, how to config them?

Best Regards

Liu Min

186-0178-0396

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MichaelF_56
Moderator
Moderator

As boont mentioned the external oscillator is optional and is utilized when increased sleep clock accuracy (PPM) is needed.  Recall that as part of the connection event, the master and slave exchange sleep clock accuracy (PPM) and the accuracy is used to determine the uncertainty window of the slave device for the duration of the connection event. This means that more accurate clocks can actually save power.

Anonymous
Not applicable

Thanks Boont and J.t for the very detailed explain.

I still have a question, I added an external 32.768kHZ crystal in the design, but cannot measure the clock out from the crystal at all, that means the external crystal don’t work at all, should I make some configuration to make it enable and stop using the internal 128KHZ LPO, how to config them?

Best Regards

Liu Min

186-0178-0396

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BoonT_56
Employee

you may want to check out this thread on configuring rtc using the 32khz crystal

how to config RTC use external 32.768?

Anonymous
Not applicable

Thanks, it’s really useful to me, will try this soon.

Best Regards

Liu Min

186-0178-0396

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