Enter Deep Power Down Mode while IRQ pin is Low

[MrVoxis]

Hello, I've an issue.

I'm working on a NXP LPC845 board where I use the Deep Power Down Mode. It works perfectly and it wakes up when I press a button (put it to low level) connected to PIO0_4 (N-WKUP).

But the pressed button has a maximum timing of 10s, after that, even if the button is pressed the software doesn't care about it and go back in low power mode (Deep Power Down Mode). 

This is where the issue is. The micro turns off when the pin PIO0_4 is on low level. After that, my software is put on a undetermined location and doesn't work anymore. A release or/and press of PIO0_4 button doesn't works. The only way to exit this situation is to press reset button..

Have you ever got this issue before ? What can I do to solve this ?  

By advance thank you for your help.

Bastien 

[MrVoxis · Accepted solution]

Several months later, I would like to help those who have the same problem I had.

When the wake-up pin is low while the microcontroller enters in deep power down mode, this creates a bug that is not foreseen by this MCU. This leads to over-consumption, and the only way to get out of this mode is a hard reset.

I advise you to perform a test on this pin before switching to deep power down mode.

To be clear:

• If wake up pin active then switch to power down (by configuring the appropriate pins and wake up on both fronts of the wake up pin).
• If wake up pin inactive then switch to deep power down mode

This greatly reduces the chances of getting stuck.

hope this helps
Kind regards

[xiangjun_rong]

Hi,

As you know that the waking-up from deep power-down mode will follow up the Reset process, we have the low power mode example in SDK package.

...LPC_SDK_MCUExpresso\SDK_2.6.0_LPCXpresso845MAX.zip\boards\lpcxpresso845max\demo_apps\power_mode_switch_lpc, which has the case to exit deep power-down mode with waking-up pin.

You can download the sdk package from the link:

https://www.nxp.com/design/software/development-software/mcuxpresso-software-and-tools-/mcuxpresso-s...

Hope it can help you

BR

XiangJun Rong