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Could I move the external 32.768kHz crystal on 51822 for keyboard application???

jimlin

Hi,

As the title said, I need more GPIOs for application, and could I use the XL1 and XL2 ?
What happen when use RC oscillator instead?

Thanks.

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  • FormerMember
    0 FormerMember

    For a BLE application, you'll need at least 250 ppm accuracy for the LF clock and this cannot be achieved with RC oscillator. The other option that you have is to use the LF clock synthesized from the HF clock. The advantage with this option apart from having 2 additional GPIOs is that you wouldn't have to wait for 0.3s for the LF OSC to settle if you stop it and you'll have predictable and low latency from waking up. But the con is that the sleep power required would be higher.

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  • FormerMember
    0 FormerMember

    For a BLE application, you'll need at least 250 ppm accuracy for the LF clock and this cannot be achieved with RC oscillator. The other option that you have is to use the LF clock synthesized from the HF clock. The advantage with this option apart from having 2 additional GPIOs is that you wouldn't have to wait for 0.3s for the LF OSC to settle if you stop it and you'll have predictable and low latency from waking up. But the con is that the sleep power required would be higher.

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