RExOS is embedded RTOS, based on exokernel architecture. It's designed for ARM microprocessors, however, can be easily ported to any 32bit MCU.

• LGPL License, open source.
• Tickless. For system scheduling used 1 HPET timer and RTC. If RTC is unavailable, another HPET timer can be used for RTC emulation
• Very thin kernel.
• Independent library level, accessible both from kernel and userspace
• Independent system and drivers in userspace
• Syncronization: ipc, stream, io
• Soft timers
• Embedded dynamic memory manager, for every process.
• Safe and MPU ready. All supervisor-specific calls are wrapped around swi/svc calls for context rising.
• Lib-level libraries:
  • ustdio: printf, sprintf. Around 2k of code.
  • ustdlib: malloc, free, realloc, atou, utoa
  • time routines
  • dynamic arrays
  • GPIO bitbang library
• User libraries:
  • USB routines library
  • GUI library: canvas, font, graphics, utf8 decoding
  • single-linked list, double linked list, ring buffer,
  • rand
  • cryptography: AES, AES-CBC, SHA1, SHA256, HMAC-SHA1, HMAC-SHA256
  • crc
• Device stacks:
  • USB device stack with USB composite and vendor requests support
  • USB device CDC ACM class
  • USB device HID Boot Keyboard class
  • USB device CCID class
  • USB device MSC class with multiple LUN and DVD-ROM support
  • USB device RNDIS class
  • SCSI stack: SPC5, SBC3, MMC6
  • TCP/IP: MAC level 802.3, RFC768, RFC791, RFC792, RFC793, RFC826
  • IP: fragmentation supported
  • ICMP: ECHO and flow control
  • ARP: timeouts and static routes support
  • DNS server
  • DHCP server
  • Web Server
  • TLS 1.2 Server (beta)
  • SD/MMC host stack with UHS support
  • uCanOpen stack
  • FAT16 file system
  • SFS / SFS v2 - small file system (commercial license)
  • Block error rate layer with transactioning support
  • BER v2 (commercial license)
  • Log file systm
  • LoRa stack
  • BLE 4.2 Host Controller (commercial license)
• Error handling:
  • each process has own error processing
  • kernel panic with memory dump on critical errors. Restart system if configured
  • handle hardware error exceptions, decode address and exception codes
• Lot of debug features:
  • memory dumps
  • object marks
  • sys objects range checking
  • user objects range checking
  • thread profiling: name, uptime, stack allocated/used
  • memory profiling: red-markings, pool free/allocated size, objects fragmentation
• Supported architecture:
  • cortex-m0
  • cortex-m3
  • cortex-m4
  • ARM7
• MCU Drivers:
  • ST STM32F0: generic, UART, RTC, WDT, SPI, I2C, USB, CAN
  • ST STM32F1: generic, UART, RTC, WDT, I2C, ADC, DAC, USB, ETH, flash
  • ST STM32F2: generic, UART, RTC, WDT, USB
  • ST STM32F4: generic, UART, RTC, WDT, USB
  • ST STM32L0: generic, UART, RTC, WDT, EEPROM, ADC, DAC, USB
  • ST STM32L1: generic, UART, RTC, WDT, I2C, USB
  • ST STM32H7: generic, UART, RTC, WDT, USB, SD/MMC, flash (commercial license)
  • NXP LPC11Uxx: generic, UART, EEPROM, USB, flash
  • NXP LPC18xx: generic, UART, USB, ETH, SD/MMC, flash
  • NXP Kinetis K22: generic, UART, RTC, WDT, I2C, USB, flash (commercial license)
  • NXP Kinetis K32W: generic, UART, USB, flash, ADC, Radio BLE (alpha) (commercial license)
  • TI CC26x0: generic, UART, RTC, WDT, Radio BLE (alpha)
  • NRF51, NRF52: generic, UART, RTC, BLE
• Other drivers:
  • МЭЛТ mt12864j LCD display
  • ESP8266
  • RF: SX1261, SX1272, SX1273, SX1276, SX1277

• Native SVC and pendSV support

• Nested interrupts
• FIQ support
• pendSV emulation, when returning to user/system context

0.7.1

• STM32 H7 support (commercial license)
• SD UHS with level switching (commercial license)

0.7.0

• Fully functional BLE host controller (commercial license)

0.6.4

• NRF51, NRF52 support
• Kinetis K32W support

0.6.3

• added Log File System (LFS) with flash retantion
• crc library

0.6.2

• LoRa device stack
• drivers for sx1261, 127x

0.6.1

• SFS is now non 2^n aligned (commercial license)
• BER v2 is up to 6 time more fast, than BER v1 (commercial license)
• MK22 flash driver rewritten for small blocks access (commercial license)

0.6.0

• ESP8266 driver
• fix multi-pool allocation error
• SVC calls trace for deep kernel debugging

0.5.9

• uart timeouts in US
• configurable comm timeouts
• CCID major refactoring, clock/rate support
• fix LPC otg memory leak
• fix MSCD multiple lun removable detection
• removed heap module
• kernel IO debug

0.5.8

• BER power-safe transaction support
• SFS - file system for internal flash (commercial license)
• CCID fix windows card presence
• STM32 ETH integrated in driver space

0.5.7

• STM32 drivers are now exodrivers. System is now fully exodrivers based
• STM32 F1 flash driver
• STM32 F1 I2C driver (master & slave)
• STM32 F0 SPI driver
• uCanOpen support PDO/SDO, persistent data saving
• CCID WTX fix (thanks to Roma Jam @github)

0.5.6

• TLS added TLS_RSA_WITH_AES_128_CBC_SHA256 cipher suite
• DNS server
• DHCP server
• STM32 F0 CAN driver
• uCanOpen (alpha)

0.5.5

• WEB server rewritten:
  • payload no more limited to MTU
  • multiple sessions support
  • custom url/parameters/data processing available
  • sessions timeouts, keep-alive or close immediatly
• STM32L1 support (thanks to Roma Jam @github)
• LPC exodrivers (experimental)

0.5.4

• BER bad block recovery
• BER error statistics
• FAT16 get free/used space
• critical exodrivers IPC fix

0.5.3

• CC26x0 Radio BLE alpha support
• HEAP sync object for dynamic object sharing
• MK22 flash support (commercial license)

0.5.2

• TI CC26x0 support
• stream write critical fix

0.5.1

• PIN hal abstraction
• fix critical kipc_post error on exodrivers
• USB sync method to avoid driver post overflow

0.5.0

• kernel-kernel IPC calls. Exodrivers support. Experimental feature
• isr own error processing
• non-block stream ISR/kernel access
• support for early hardware init
• support for cortex-mX custom flash layout
• no more generated asm_defines.h
• STM32 F102, F103 USB driver support. Thanks to zurabob

0.4.9

• LPC18xx flash storage interface
• Block error rate for filesystem over flash support
• FAT16 minor fixes

0.4.8

• Support of FAT16 file system: read, write, format
• FAT16 VFS drafts

0.4.7

• STM32F0 USB driver
• STM32F0 UART IO mode driver
• USB drivers now part of CORE drivers, no more dedicated SYS_OBJ_USB handle

0.4.6

• STM32 F0 support
• STM32 HAL interface for clocks query

0.4.5

• LPC18xx power profiling support
• HAL syntax for frequencies request
• Minor fixes in LPC18xx drivers

0.4.4

• USB Mass storage multiple LUN support
• MMC6 SCSI
• USB Mass storage DVD-ROM support
• GPIO now userspace library
• Dynamic arrays in kernel by lib layer (Array, SO)
• Multiple system pools support with dynamic configuration
• LPC OTG driver DTD conveyor to support IO's more than 20KB
• LPC18xx every memory chunk is transparent available for user
• Extended pool statistics in process_info()

0.4.3

• SD/MMC host interface
• HAL type independent storage interface
• SCSI refactoring for making storage interface compatible
• USB device configuration templates
• USB MSC transparent storage interface
• LPC18xx SD/MMC driver

0.4.2

• Some cryptography: AES, AES-CBC, SHA1, SHA256, HMAC-SHA1, HMAC-SHA256
• TLS 1.2 support (beta). Transparent to TCP/IP stack

0.4.1

• USB RNDIS class support
• USB interface associations descriptor support
• USB transparent HAL interface
• minor fixes in HTTP server, TCP/IP stack

0.4.0

• HTTP server (beta)
• LPC18xx ethernet driver
• minor TCP/IP fixes

0.3.9

• TCP/IP stack full support. Fragmentation safe
• SO: fragmentation-safe object handles support library
• Example updated to support both USB (cdc echo) and TCP/IP telnet(23) echo

0.3.8

• IPC request flag. No need to check if response on IPC is required anymore
• HAL_REQ, HAL_IO_REQ helpers to make CMD for IPC request
• IPC get refactoring:
  • get_handle when handle is expected. If error is set, INVALID_HANDLE is returned
  • get_size for IO operations. Negative value means error
  • get_int for generic int. Error is set, but original param2 returned
• error codes refactoring. Synthetic ERROR_SYNC added as helper for asynchronous IPC request completion
• IP stack refactoring
• ARP static routes and debug info
• ICMP echo request simplified. More detailed flow control

0.3.7

• UART flush HAL
• UART IO interface for block transfers
• LPC uart IO interface
• soft timers start/stop in ISR
• USB device high-speed fix

0.3.6

• LPC18xx USB1 & both usb support
• LPC18xx, LPC11U6x I2C support
• I2C HAL interface

0.3.5

• LPC18xx USB0 support
• IPC size is now fixed by KERNEL_IPC_COUNT
• simplified process name store mechanism
• lib_heap removed
• REX_HEAP_FLAGS is now just REX_FLAG_PERSISTENT_NAME
• PROCESS -> KPROCESS, HEAP -> PROCESS
• __HEAP -> __PROCESS
• size of created processes not includes process system header
• pinboard soft timer interface
• removed ipc/io calls timeouts requests. Use soft timers instead
• IO is now integrated part of IPC. HAL_IO_CMD added to work as helper
• SYS_OBJ_PINBOARD, SYS_OBJ_USBD objects not created by process, only hardware drivers and STD
• IPC queue in userspace
• IPC message peek in userspace
• EEP HAL interface updated: no more seek. handle is offset from base
• LPC, STM32 EEP HAL update

0.3.4

• LPC18xx basic support: PIN/GPIO, UART, TIMER, POWER

0.3.3

• due to different meaning in LPC18xx of PIN and GPIO, HAL_GPIO is now HAL_PIN. GPIO is only userspace library, while PIN configuration is in driver space
• GPIO is now required library
• LPC18xx architecture decoding
• LPC18xx GPIO driver
• KERNEL_INFO now called KERNEL_DEBUG
• fix CCID EP size request halts

0.3.2

• Y2037 compatible, no POSIX time_t is used anymore. Up to 1M year date supported with BC (by design)
• TIME is now SYSTIME, time_t now TIME
• STM32 RTC driver update for new TIME interface
• SCSI stack: SBC3 write caching support

0.3.1

• USB mass storage class
• SCSI stack: SPC5, SBC3

0.3.0

• New sync object - io. block successor with embedded header and stack
• block and direct are now deprecated
• lpc/stm32 drivers, usb device stack moved to io interface
• array now userspace library
• ccid device interface simplified
• usb descriptor parser moved to userspace usb part
• usb descriptor registering interface simplified
• ipc_read now automatically answer on IPC_PING and clearing last error

0.2.9

• HAL is now part of cmd in IPC
• new HAL item: USBD_IFACE. USBD class interface updated
• removed obsolete mutex, event, semaphore from project code

0.2.8

• LPC UART, timer HAL interface
• STM32 L0 EEPROM driver

0.2.7

• Run time power management support with HAL interface
• hardware timer (htimer) HAL interface
• UART HAL interface
• STM32 HAL drivers: UART, power, timer
• STM32 L0 low power support
• USB device virtualbox workaround

0.2.6

• DAC driver HAL abstraction
• ADC driver HAL abstraction
• STM32 analog driver splitted into ADC and DAC
• STM32 L0 ADC and DAC drivers
• software wave generation module for driver
• IPC call waits for exact command, sended to process
• fix unsafe task switching, when process statistics is enabled

0.2.5

• STM32 F1 ehternet driver with double buffering supported
• TCP/IP scratch: MAC, MAC filtering, ARP resolve/announce, ARP cache, IP, ROUTE, ICMP echo, ICMP ping, ICMP flow control
• ARRAY refactoring: no more division operations, interface is more simple. Now it's required library.
• libusb splitted to midware USB descriptor helpers and userspace libusb
• soft rand routines now userspace lib
• GUI is now userspace lib

0.2.4

• LPC 11Uxx EEPROM driver
• no more splitted calls. Response is same as request
• direct read/write can work in partial mode
• new file API. IPC_IO_CANCELLED, IPC_READ_COMPLETE, IPC_WRITE_COMPLETE is now obsolete.
• file API supports direct mode
• new sys interface. Recommended abstraction: param1 - handle, param2 - object, param3 - size or error. Get returns value in param2.
• critical fix in IPC queue
• USB CCID device state machine fix
• USB device support for vendor specific requests
• USB device suspend/resume support

0.2.3

• USB CCID device class
• USB device support wakeup/resume on linux
• LPC USB driver fixes
• IPC_IO_CANCEL, IPC_IO_CANCELLED file abstraction
• kprocess time statistics fixed

0.2.2

• kernel soft timers
• USB device HID Boot keyboard class
• fix fifo alignment in LPC USB driver

0.2.1

• GUI library
• MT driver update for GUI objects support
• LPC USB minor fixes

0.2.0

• drivers for LPC11Uxx USB device, МЭЛТ LCD display
• GPIO bitbang is now library for fast IO (lib_gpio), implementation is hw-specific
• USB helpers implemented as library (lib_usb)
• ARRAY (lib_array) supports custom data size
• USB classes now interface of USB device
• USB composite device support
• KERNEL_OBJECTS more standartized, requiring less parameter transfer
• most of headers are going to /userspace, less dependancy required
• critical fixes in memory pool, stream, ipc.
• new virtual handles: ANY_HANDLE, KERNEL_HANDLE

0.1.3

• drivers for LPC11Uxx
• STM32 bitbang driver template
• file api mode support

0.1.2

• dynamic BLOCK links
• some optimization in kernel_config.h
• HAL drivers for STM32
• STM32 analog, USB, UART can be optionally monolith for small systems

0.1.1

• global lib refactoring
• lib heap
• persistent names flag for process
• some STM32 driver refactoring
• HAL driver abstraction started

0.1.0

• No IDLE process required anymore. All idle execution is going on PendSV level
• Some critical bug fixes in process switching

0.0.5

• No system process anymore, replaced by kernel objects
• IRQ handlers now in dynamic memory, saving some space
• persistent kernel name
• kernel/user stack profiling with max stack usage

0.0.4

• interrupt friendly kernel calls for faster realtime response
• dynamic array library
• (system) basic file level abstraction
• (system) USB STM32F1 CL drivers
• (system) USB device stack
• (system) USB CDC stack

0.0.3

• new sync objects: direct IO, block
• mutex, events, sempaphores are now deprecated

0.0.2

• new sync objects: ipc, stream
• new sys level - userspace system
• support for STM32F2 fixed (not tested)

0.0.1

• Fork from M-Kernel (https://github.com/alexeyk13/mkernel)
• New dynamic memory pool manager
• Process has own heap with own error handling, stack and heap, all inside paged block
• support for ARM7 broken
• support for STM32F2 broken
• support for softNVIC(ARM7) broken