RT

Skynet RT is an Apache 2.0 licensed fork of NuttX. See the NOTICE message and HISTORY changelog for additional details.

Emulation

Execute RT binary using QEMU.

./tools/configure.sh qemu-armv7a:nsh
kconfig-mconf Kconfig
./tools/mkconfig . > include/nuttx/config.h
make -j
qemu-system-arm -M virt -device loader,file=nuttx -nographic

Simulation

Run RT as POSIX Application.

./tools/configure.sh sim:nsh
kconfig-mconf Kconfig
./tools/mkconfig . > include/nuttx/config.h
make -j
./nuttx

Bare Metal

Run RT on Bare Metal like Raspberry Pi Pico 2 (RP2350).

./tools/configure.sh raspberrypi-pico-2:usbnsh
kconfig-mconf Kconfig
./tools/mkconfig . > include/nuttx/config.h
make -j
picotool uf2 convert nuttx.bin nuttx.uf2 --family absolute --offset 0x10000000

CONFIG

Configuration Menu using kconfig.

$ kconfig-mconf Kconfig

HAL

Hardware Abstraction Layer

HAL defines set of include files for CHIPS and BOARDS supported by RT.

rts/
├── include/
│   ├── arch/
│   │   ├── [chip]/
│   │   └── [board]/

CHIPS

CHIPS folder defines hardware abstractions for CPU or SoC which include GPIO, I2C, SPI, UART and Timer harware definition for SoC built-ins.

ARMv7-M — ARMv7-M 32-bit MCU Profile.
ARMv7-A — ARMv7-A 32-bit Profile.
ARMv8-M — ARMv8-M 32-bit MCU Profile.
ARMv8-A — ARMv8-A 64-bit Profile.
BCM2711 — Broadcom BCM2711.

rts/
├── hal/
│   ├── chips/
│   │   └── [chip]/
│   │       ├── cpu/
│   │       ├── mmu/
│   │       └── drivers/
│   │           ├── gpio/
│   │           ├── i2c/
│   │           ├── spi/
│   │           ├── uart/
│   │           ├── timer/
│   │           └── misc/

BOARDS

BOARDS folder fefines hardware abstractions for I/O Boards where SoC is placed. Thus the BOARD primitives include by inheritance all CHIP primitives plus Boot, PWM, ADC, Sensors and Power hardware board facilities.

CXD56XX — Sony Spresense.
PICO2 — Raspberry Pi Pico 2.
VIRTIO — QEMU Virtio.
SIM — Simulation.

rts/
├── hal/
│   ├── boards/
│   │   └── [board]/
│   │       ├── init/
│   │       ├── linker/
│   │       └── drivers/
│   │           ├── gpio/
│   │           ├── i2c/
│   │           ├── spi/
│   │           ├── uart/
│   │           ├── timer/
│   │           ├── misc/
│   │           ├── pwm/
│   │           ├── adc/
│   │           ├── sensors/
│   │           └── power/

KERNEL

RT Kernel.

LDR — ELF/FLAT Binary Loader.
CLK — Clocks and Counters.
IRQ — Interrupts.
SIG — Signaling System.
TIM — Timers.
SCH — Scheduler.
MM — Memory Manager.
MQ — Message Queues.
THR — Threads.
SEM — Semaphores.
ENV — Environment Variables.
TSK — Task Processes.

DRIVERS

Device Drivers.

EEPROM — EEPROM Access.
FDT — Flattened Device Tree.
I2C — I2C Bus.
PCI — PCI/PCIe Bus.
USBDEV — USB Device Driver.
USBHOST — USB Host Driver.
UART — UART Serial Driver.

FS

File Systems.

Virtual — File System (/).
ROM — File System (/etc).
BIN — File System (/bin).

LIBS

Libraries.

LIBC — C Run-Time Library.
LIBM — Mathematical Library.

APPS

Applications.

INIT — RT Init Supervisor.
SH — POSIX Verified Shell.
SKYNET — Skynet Application.