SPRESENSE is the code name of the product CXD5602 produced by Sony Semiconductor Solutions Corporation.
The CXD5602 is ARM powered SoC, including many peripherals for IoT and wearable solutions.

SPRESENSE SDK is based on NuttX. So please refer to original NuttX site to see basic kernel information.

This SDK constructed by series of libraies, drivers and architecture specific code, these helps to you getting started and create faster for your products.

Directory structure

sdk
|-- bsp            - Board support package
|   |-- board      - Board specific code
|   |-- include    - SDK headers
|   |-- scripts    - Linker scripts
|   `-- src        - Common source
|-- configs        - Default configuration files
|   `-- kernel
|-- drivers        - External device drivers
|   |-- lcd
|   `-- sensors
|-- lib            - Kernel and SDK library output directory
|-- modules
|   |-- asmp       - ASMP framework
|   |-- audio      - Audio library
|   |-- fwuputils  - Firmware update utility
|   |-- include    - Library headers
|   |-- sensing    - Smart sensing library
|   |   |-- arm_gesture   - Arm gesture detection
|   |   |-- barometer     - Barometer
|   |   |-- compass       - Compass
|   |   |-- gnss          - GNSS
|   |   `-- tap           - Tap detection
|   `-- skeleton
|-- system         - System commands
`-- tools          - Build utilities

Build instruction

Getting started

$ make buildkernel KERNCONF=release
$ tools/config.py default
$ make

SDK and NuttX kernel's configuration and build sequence are separated.

Configuration

SDK provides tools/config.py as configuration frontend for SDK and NuttX kernel configuration. tools/config.py invokes kconfig tool so this must be installed prior it is used. tools/config.py must be called from top of SDK source tree.

tools/config.py can be switched with -k or --kernel option to configure the kernel. If no -k or --kernel option has been specified, then the configuration affects SDK.

e.g.

$ tools/config.py --kernel --list (list kernel predefined configs)
$ tools/config.py --list  (list SDK predefined configs)

The first timeyou run SDK setup, or if you want to change to predefined config, specify predefined <config name> as parameter:

$ tools/config.py <config name> [<config name>...]

You can specify multiple predefines, it allows combination of predefines.

e.g.

$ tools/config.py audio gnss

tools/config.py can be invoked menu style configuration UI by following options.

$ tools/config.py --menuconfig (same as 'make menuconfig')
$ tools/config.py --qconfig    (same as 'make qconfig')
$ tools/config.py --gconfig    (same as 'make gconfig')

Additionally, you can use menu invokation with predefined configs like this:

$ tools/config.py --menuconfig default

Save your configuration

If you want to save your edited options, then try tools/mkdefconfig.py. It is for saving user configuration as predefined config.

You can save current SDK configuration like this:

$ tools/mkdefconfig.py <config name>

And also kernel configuration too.

$ tools/mkdefconfig.py -k <config name>

After that, you can choose their saved default configs to specify tools/config.py's config name.

If your specified config name is already exists, tools/mkdefconfig.py shows comfirm message to overwrite.

By default, tools/config.py and tools/mkdefconfig.py find out specified configurations under configs directory. You can change the default configuration file directory with -d or --dir option, both of tools/config.py and tools/mkdefconfig.py are supported.

If you want to save your customized configuration to where you want, type like this:

$ tools/mkdefconfig.py -d ../path/to/configs <config name>

When you want to use configurations in alternative directory:

$ tools/config.py -d ../path/to/configs <config name>

Also they can be use -k option with -d to saving/restoring kernel configuration.

Build

SDK build system has been separated from NuttX, it to be able to build NuttX kernel indipendently, and build SDK faster. User must be build kernel before SDK build by following command.

$ make buildkernel

If you don't interest about kernel sources, then never been built again. And you can specify kernel default config from KERNCONF, configure specified config and build at the same time.

$ make buildkernel KERNCONF=<config name>

Finally, build SDK drivers and libraries.

$ make

After built successfully, you can see nuttx and nuttx.spk files in top of SDK source tree.