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espressif / esp-zigbee-sdk

Espressif Zigbee SDK
Apache License 2.0
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Is this SDK benefit from a 32.768kHz crystal ? (TZ-928) #364

Closed X-Ryl669 closed 5 months ago

X-Ryl669 commented 5 months ago

Question

In the BLE case, mounting an 32.768kHz crystal on the 2 specific crystal pin allows the system to go from few mA to tens of µA because the BLE communication can enter light sleep instead of modem sleep between advertisements.

Shall we expect the same benefit here for Zigbee when mounting a crystal on the PCB?

I've seen the deep sleep and light sleep example, so I guess it's possible to actually (light or deep) sleep in the (long) poll interval. But in the short time the device is awake, will it go to modem sleep or to light sleep when the radio is silent?

Additional context.

No response

xieqinan commented 5 months ago

@X-Ryl669 ，

Shall we expect the same benefit here for Zigbee when mounting a crystal on the PCB?

The 32.768kHz crystal does not benefit the Zigbee SDK in general cases.

will it go to modem sleep or to light sleep when the radio is silent?

If the awake time is less than 3 ms (as defined by CONFIG_FREERTOS_IDLE_TIME_BEFORE_SLEEP), the device will remain active and will not enter any sleep mode. Otherwise, it allows the device to re-enter light sleep when the radio is silent.

chshu commented 5 months ago

The 32.768kHz crystal could benifie the BLE sleep mode, since it can guarantee the timing accuracy during light sleep, and the BLE communication requies this timing accuracy. But it's not requied by Zigbee sleep mode.

The sleep threshold can be configrured by esp_zb_sleep_set_threshold() API, which is 20ms by default, that means if the idle time is longer than 20ms, it will enter light sleep.