Detect wakeup source after Deep Power-down

[vanska]

Hi,

I'm using Deep Sleep and Deep Power-down in our application. In both the wakeup can be triggered by RTC alarm and two GPIOs (Deep Sleep: PINT, Deep Power-down: dedicated wakeup pins).

I need to use Deep Power-down to minimize the power consumption for most of the time (Power-down is not an option since it drives all pins low). The problem is that I also need to know which wakeup source I can blame after the wakeup. In Deep Power-down a wakeup causes a chip reset which means I cannot use RTC general purpose registers to store the wakeup source data (I assume there's no time for using ISR before the reset occurs).

Is there any way I could see the wakeup source after waking up from Deep Power-down?

I'm using LPC55S28.

Thanks.

[ZhangJennie · Accepted solution]

Hi vanska 

We can check general purpose always on domain data storage. I extract it from UM11126.If this doesn't help, please contact me again. 

ZhangJennie_0-1685677592174.png

This is General purpose always on domain data storage.

Remark: This register is managed and updated by the ROM boot and cannot be updated by any application.

Hope this helps,

Jun Zhang

[vanska]

Thanks @ZhangJennie!

I was already using AOREG1 storage for logging purposes but the problem was that it didn't provide information about which I/O caused the wakeup (indeed it shows if it was caused by the RTC alarm or some wakeup pin). But after taking another look at the user manual, I found the WAKEIOCAUSE register which was the missing piece of the puzzle. Now it works perfectly!

vanska_0-1686670536024.png