Application Event Manager

The Application Event Manager sample demonstrates the functionality of the Application Event Manager subsystem. It uses an event-driven architecture, where different modules communicate through sending and processing events.

Overview 

The sample application consists of three modules that communicate using events:

Sensor (sensor_simulated.c):: This module waits for a configuration event (which is sent by main.c). After receiving this event, it simulates measured data at constant intervals. Every time the data is updated, the module sends the current values as measurement event. When the module receives a control event from the Controller, it responds with an ACK event.
Controller (controller.c):: This module waits for measurement events from the sensor. Every time a measurement event is received, the module checks one of the measurement values that are transmitted as part of the event and, if the value exceeds a static threshold, sends a control event.
Statistics (stats.c):: This module waits for measurement events from the sensor. The module calculates and logs basic statistics about one of the measurement values that are transmitted as part of the event.

Requirements 

The sample supports the following development kits:

Hardware platforms	PCA	Board name	Build target
nRF9160 DK	PCA10090	nrf9160dk_nrf9160	`nrf9160dk_nrf9160_ns`
nRF5340 DK	PCA10095	nrf5340dk_nrf5340	`nrf5340dk_nrf5340_cpuapp_ns` `nrf5340dk_nrf5340_cpuapp`
nRF52 DK	PCA10040	nrf52dk_nrf52832	`nrf52dk_nrf52832`
nRF52840 DK	PCA10056	nrf52840dk_nrf52840	`nrf52840dk_nrf52840`
nRF21540 DK	PCA10112	nrf21540dk_nrf52840	`nrf21540dk_nrf52840`

When built for an _ns build target, the sample is configured to compile and run as a non-secure application with Cortex-M Security Extensions enabled. Therefore, it automatically includes Trusted Firmware-M that prepares the required peripherals and secure services to be available for the application.

Configuration 

See Configuring and building an application for information about how to permanently or temporarily change the configuration.

Building and running 

This sample can be found under samples/app_event_manager in the nRF Connect SDK folder structure.

When built as firmware image for the _ns build target, the sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M). To read more about CMSE, see Processing environments.

To build the sample with Visual Studio Code, follow the steps listed on the How to build an application page in the nRF Connect for VS Code extension documentation. See Configuring and building an application for other building scenarios, Programming an application for programming steps, and Testing and optimization for general information about testing and debugging in the nRF Connect SDK.

Testing 

After programming the sample to your development kit, test it by performing the following steps:

Connect to the kit with a terminal emulator (for example, nRF Connect Serial Terminal). See Testing and optimization for the required settings and steps.
Reset the kit.

Observe that output similar to the following is logged on UART:

***** Booting Zephyr OS v1.13.99-ncs1-4741-g1d6219f *****
[00:00:00.000,854] <inf> app_event_manager: e: config_event init_val_1=3
[00:00:00.001,068] <inf> app_event_manager: e: measurement_event val1=3 val2=3 val3=3
[00:00:00.509,063] <inf> app_event_manager: e: measurement_event val1=3 val2=6 val3=9
[00:00:01.018,005] <inf> app_event_manager: e: measurement_event val1=3 val2=9 val3=18
[00:00:01.526,947] <inf> app_event_manager: e: measurement_event val1=3 val2=12 val3=30
[00:00:02.035,888] <inf> app_event_manager: e: measurement_event val1=3 val2=15 val3=45
[00:00:02.035,949] <inf> app_event_manager: e: control_event
[00:00:02.035,980] <inf> app_event_manager: e: ack_event
[00:00:02.544,830] <inf> app_event_manager: e: measurement_event val1=-3 val2=12 val3=57
[00:00:03.053,771] <inf> app_event_manager: e: measurement_event val1=-3 val2=9 val3=66
[00:00:03.562,713] <inf> app_event_manager: e: measurement_event val1=-3 val2=6 val3=72
[00:00:04.071,655] <inf> app_event_manager: e: measurement_event val1=-3 val2=3 val3=75
[00:00:04.580,596] <inf> app_event_manager: e: measurement_event val1=-3 val2=0 val3=75
[00:00:04.580,596] <inf> stats: Average value3: 45