XIAO_BLE wakes up from System_ON_Sleep and Writes weather data to on-board Flash

Products & Technology XIAO
29

It took some time to re-experiment and summarize the data, then I found the following

  1. runCommand() can enter but cannot release. However, if the sleep time is less than 200mS, it can be released.
  2. SPI.transfer() can enter and release with no problem.

My hypothesis is that XIAO sends “0x05” to Flash in DeepPowerDown mode and waits for a reply, but Flash ignores it and times out, as described in post 17.

I will now read the Nordic information more carefully.

nRF52_XIAO_LightSleep_enter_release_begin.zip (1.5 KB)

Since the oonboard Flash cannot observe waveforms, I connected an external Flash to observe waveforms.

SPIwaveform
SPIwaveform932×820 186 KB

CannotRerlease
CannotRerlease1054×753 136 KB