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.
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:
Use the Memory report feature in the nRF Connect for VS Code extension to check the size and percentage of memory that each symbol uses on your device for RAM, ROM, and partitions (when applicable).
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.
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
Security Manager Protocol (if no encryption and authentication is needed)
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
Besides applying General recommendations and Bluetooth optimization actions, there are some configuration options you can use to optimize the Bluetooth mesh part of your application. Changing any of these options will change the functional capabilities of the Bluetooth mesh device, and thereby result in changes to RAM and flash memory footprint.
Changing the values of the following options will affect the RAM footprint and the amount of space needed for persistent storage of the associated configuration data:
General node configuration:
For Provisioner device, the following configuration database (CDB) options are available (like how many nodes it can provision, or maximum number of supported application keys):
Changing the values of the following options will only affect the RAM footprint:
Configuration options for segmented messages (for example how many segmented messages a node can send or receive, and the number of segments per message):
Extended advertising configuration:
Legacy advertising configuration:
If Friend feature is enabled, the following configuration options are relevant:
If Low Power node (LPN) feature is enabled, the following configuration option is relevant:
If the proxy server is enabled (option
BT_MESH_GATT_PROXY), pay attention to the proxy server filter size:
Other device configuration:
Model configuration options that affect stack size at runtime:
To optimize the Gazell memory footprint, follow the General recommendations. Specifically, study the ISR stack size. If your application is in a pairing device, pay attention to the system workqueue stack size.
Do not enable features that your application does not use. The configuration options default to disabling optional features, such as:
Pairing settings persistent storage
To reduce the logging level, set the
CONFIG_GAZELL_LOG_LEVEL_CHOICE Kconfig option.
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_release.conffor building the application. The release configuration has a smaller memory footprint than the default, debug-enabled
If the logs in your application do not use the default log level, you can change the default log level of Zephyr modules from
Change the log level of the Matter logs from
Reduce the verbosity of assert messages by setting
Check Thread memory footprint optimization actions, as the Matter application layer uses OpenThread.
Additionally, you can turn off logging for single Matter modules on the Matter SDK side, as described in Cutting off log regions for Matter SDK modules.
The Near Field Communication (NFC) protocol implementation in the nRF Connect SDK provides some options for optimizing memory footprint for both the tag and the poller roles.
To optimize your application that supports the NFC tag functionality, follow the General recommendations. The NFC Type 2 Tag and Type 4 Tag libraries do not provide configuration options that have an effect on memory usage in an application. However, there are a few Kconfig configuration options you can use to optimize memory usage related to NFC.
CONFIG_NFC_PLATFORM_LOG_LEVEL_CHOICEto reduce logging level in the NFC integration module.
For an application that uses the Type 4 Tag library, you can set the following options:
To optimize an application that supports the NFC poller functionality using the NFC Reader ST25R3911B library, you can set the following options:
CONFIG_ST25R3911B_LIB_LOG_LEVEL_CHOICEand similar options to reduce the logging level of the NFC components used in the application.
If the application supports the Tag NDEF Exchange Protocol (TNEP), you can set the following options:
CONFIG_NFC_TNEP_POLLER_RX_MAX_RECORD_CNTfor the maximum number of NDEF records in the received message.
If the application uses the NFC TNEP protocol for the Bluetooth LE out-of-band pairing procedure (NFC TNEP Connection Handover), regardless of the role (tag or poller), you can set the following options:
The current Thread memory requirements are listed on the OpenThread memory requirements page.
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:
The current Wi-Fi® memory requirements are listed on the Memory requirements for Wi-Fi applications page.
In addition to applying General recommendations, you can also see the Operating with a resource constrained host page to optimize the Wi-Fi stack of your application. Specifically, you can refer to the section on networking stack or memory fine-tuning controls which lists Kconfig options that can be used to reduce memory requirements of your application.
The current Zigbee memory requirements are listed on the Zigbee memory requirements page.