Skip LPC55x boot code after returning low-power mode

[SantiRP]

We are developing a low-power application which switches between the "run" and the "deep power down" mode. Most of the time the program is in deep power down mode and from time to time it wakes up to perform very quick actions in order to return to sleep mode as soon as possible.

However, every time the program wakes up from the deep power down, it runs the boot code again. This has the consequence of a too long time in the run mode making the average consumption increase dramatically.

Is there a possibility to skip the boot code of the LPC5506 and jump straight to the application program?

[Julián_AragónM]

 Hi @SantiRP,

According to the reference manual, in chapter 13.3.6.6 (Wake-up from deep-power down mode), the microcontroller will do a reset process on wakeup:

"The part goes through the entire reset process when a deep-power down wake-up event occurs:

• The PMU will turn ON the on-chip voltage regulator. When the core voltage reaches the Power-ON-Reset (POR) trip point, a system reset will be triggered and the chip boots.
• All registers will be in their reset state."

If the reset process is an inconvenience to your application, I would suggest looking into the chapter 13.3 (Functional description of power management) to select between the other low power modes.

There is also an example for the selection of this low power modes in the SDK of this part. It is called "power_manager_lpc" under "demo_apps" and it shows the usage of normal power mode control APIs for entering the three kinds of low power mode: Sleep mode, Deep Sleep mode and Sleep Power Down mode.

I hope you find this helpful!

Best regards, Julian

[SantiRP]

Thank you for your quick response. The problem with the rest of the low power modes is that their consumption is too high for our power requirements. This is the reason why we wanted to wake-up from deep-power down mode but without running the boot rom.

Best regards,

Santi