Memory footprint optimization
When developing an application, ROM and RAM footprint are important factors, especially when the firmware runs on the most resource-constrained devices like nRF52810 or nRF52811.
General recommendations
To reduce the memory footprint, ensure that your application uses the minimum required resources and tune the nRF Connect SDK configuration parameters. Complete the following actions to optimize your application:
Follow the guides for optimizing Zephyr. Also see the implementation of the Minimal footprint sample.
Analyze stack usage in each thread of your application by using the Thread analyzer. Reduce the stack sizes where possible.
Limit or disable debugging features, such as logging or asserts.
Go through each component and subsystem and turn off all peripherals and features that your application does not use.
The following subsections give more information on how to optimize specific subsystems.
Bluetooth
Besides applying General recommendations, you can also complete the following actions to optimize the Bluetooth® part of your application:
Disable features that your application does not use. For example, disable the following features:
Data Length Update
Extended Advertising
PHY Update
Security Manager Protocol (if no encryption and authentication is needed)
GATT Caching
GATT Service Changed
Reduce the stack sizes of the Bluetooth internal threads where possible. Use the Thread analyzer to analyze the stack usage.
The following configuration options affect the stack sizes of the Bluetooth threads:
Reduce the overall number and the sizes of the Bluetooth buffers, based on the expected data traffic in your application.
The following configuration options affect the Bluetooth buffers:
For reference, you can find minimal footprint configurations of the Bluetooth: Peripheral LBS sample in nrf/samples/bluetooth/peripheral_lbs/minimal.conf
and the Bluetooth: Peripheral UART sample in nrf/samples/bluetooth/peripheral_uart/minimal.conf
.
Matter
Besides applying General recommendations, you can also complete the following actions to optimize the Matter part of your application:
Make sure Zephyr’s Shell is disabled for your application. Related configuration options are listed in a dedicated section in each Matter sample’s
prj.conf
file.Use
prj_release.conf
for building the application. The release configuration has a smaller memory footprint than the default, debug-enabledprj.conf
.If the logs in your application do not use the default log level, you can change the default log level of Zephyr modules from
info
towarning
by settingCONFIG_LOG_DEFAULT_LEVEL
to2
.Change the log level of the Matter logs from
debug
toinfo
by settingCONFIG_MATTER_LOG_LEVEL_INFO
toy
.Reduce the verbosity of assert messages by setting
CONFIG_ASSERT_VERBOSE
ton
.Check Thread memory footprint optimization actions, as the Matter application layer uses OpenThread.
Thread
The current Thread memory requirements are listed on the OpenThread memory requirements page.
Besides applying General recommendations, you can also complete the following actions to optimize the Thread part of your application:
Disable Thread features that your application does not use. For example, disable network shell and OpenThread CLI shell support (see Additional configuration options)
Reduce the stack sizes of the Thread internal threads where possible. Use the Thread analyzer to analyze the stack usage.
The following configuration options affect the stack sizes of the Thread threads:
For reference, you can find minimal footprint configurations for the single protocol and multiprotocol variants of the Thread: CLI sample in nrf/samples/openthread/cli/overlay-minimal_*protocol.conf
.
Zigbee
The current Zigbee memory requirements are listed on the Zigbee memory requirements page.
Apply General recommendations to optimize the Zigbee part of your application.