LPC8N04 Wakeup from Deep-Power-Down

[kenchill]

LPC8N04 Wakeup from Deep-Power-Down.

We have a project that requires the LPC8N04 to wakeup from DPD by NFC, RTC or WAKEUP pin, the problem is detecting the source of wakeup - as the LPC8N04 cannot be debugged in DPD we are toggling i/o pins to detect states.

1) We are finding that it takes 6ms or so before any NFC status flags can be used (apart from the PSWNFC bit in the PSTAT register).

2) When woken by either NFC or WAKEUP pin the 'RTC Timer Event' flag gets set in the PSTAT register - this flag doesn't get set if the RTC woke the device.

3) If the RTC wakes the device the 'LDO Enabled' flag gets set in the PSTAT register.

Are we missing something? Or is this how the LPC8N04 functions? If it is how the LPC8N04 functions is it reliable and safe to use these flags?

I hope someone can help

Thanks in advance

Ken...

[IvanRuiz]

Hello,

The NFC status flags should wait to the chip get ready, it should depend on detailed application initial process.

For wake up flag of different wake up source, Could you check DPDFLAG in the PCON register whether asserted in your testing code? It need be asserted to get DPDEXIT flag work. 

BR,

Ivan.