Skip to content

System OFF

Overview

The System OFF sample can be used for basic power measurement and as an example of deep sleep on the nRF54L15 Connect Kit.

This sample can also demonstrate RAM retention. By selecting CONFIG_APP_USE_RETAINED_MEM=y state related to number of boots, number of times system off was entered, and total uptime since initial power-on are retained in a checksummed data structure. RAM is configured to keep the containing section powered while in system-off mode.

Requirements

Before you start, check that you have the required hardware and software:

Building the sample

To build the sample, follow the instructions in Getting Started Guide to set up your preferred building environment.

Use the following steps to build the System OFF sample on the command line.

  1. Open a terminal window.

  2. Go to NCS-Project/nrf54l15-connectkit repository cloned in the Getting Started Guide.

  3. Build the sample using the west build command, specifying the board (following the -b option) as nrf54l15_connectkit/nrf54l15/cpuapp.

    west build -p always -b nrf54l15_connectkit/nrf54l15/cpuapp samples/system_off

    west build -p always -b nrf54l15_connectkit/nrf54l15/cpuapp samples/system_off -- -DCONFIG_APP_USE_RETAINED_MEM=y

    Tip

    The -p always option forces a pristine build, and is recommended for new users. Users may also use the -p auto option, which will use heuristics to determine if a pristine build is required, such as when building another sample.

  4. After building the sample successfully, the firmware with the name merged.hex can be found in the build directory.

Flashing the firmware

Connect the nRF54L15 Connect Kit to the computer with a USB-C cable:

Then flash the sample using west flash:

west flash

Tip

In case you wonder, the west flash will execute the following command:

pyocd load --target nrf54l --frequency 4000000 build/merged.hex

Testing

After programming the sample, test it by performing the following steps:

  1. Open up a serial terminal, specifying the primary COM port that your computer uses to communicate with the nRF54L15:

    1. Start PuTTY.

    2. Configure the correct serial port and click Open:

    Open up a terminal and run:

    screen <serial-port-name> 115200

    Open up a terminal and run:

    screen <serial-port-name> 115200

  2. Press the DFU/RST button to reset the nRF54L15.

  3. Observe the output of the terminal. You should see the output, similar to what is shown in the following:

    Terminal
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***

nrf54l15_connectkit system off demo
Other wake up cause 0x00000001.
Retained data not supported
Entering system off; press sw0 to restart
*** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***

nrf54l15_connectkit system off demo
Wakeup from System OFF by GPIO.
Retained data not supported
Entering system off; press sw0 to restart
...
    Terminal
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***

nrf54l15_connectkit system off demo
Other wake up cause 0x00000001.
Retained data: valid
Boot count: 1
Off count: 0
Active Ticks: 548
Entering system off; press sw0 to restart
*** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***

nrf54l15_connectkit system off demo
Wakeup from System OFF by GPIO.
Retained data: valid
Boot count: 2
Off count: 1
Active Ticks: 317829
Entering system off; press sw0 to restart
...