Sleep TImes XBee XR 868

XBee & XBee Gateway
1

Hey I wanted to follow up regarding the sleep timing. Today I noticed that a significant amount of time is unnecessarily lost during SPI communication.

According to the datasheet, the entire process—from receiving data via SPI to transmitting it over RF, including the host wake-up—should take around 20 ms.

However, no matter what I try, I can’t get the XBee XR868 to stay awake for less than 250 ms (whether using Sleep Request, Pin Sleep, or Cyclic Sleep).
Interestingly, if I only send data to the XBee via SPI without it actually transmitting anything over RF, it wakes up and is able to go back to sleep after just 45 ms.

Since this is for a very low-power project, I would really like to know:
a. Why is this happening?
b. Is there any way to reduce the wake time?

2

The timing you are seeing is most likely a result of any retries or broadcast transmissions that are occurring. * For devices in asynchronous cyclic sleep, ST defines the amount of time that a device stays awake after it receives RF or serial data. The Hex value for the ST command is in 1ms increments.