embOS for STMicroelectronics ST7 CPUs and COSMIC compiler

embOS for ST7 was developed for and with COSMIC's CXST7 compiler and supports the long stacked memory model offered by this compiler. It comes with easy to use start projects for COSMIC's IdeaST7 embedded workbench. Software development with debugger or ZAP simulator is supported.

Resources and performance data

Memory usage
Kernel size (ROM)	approx. 2000 bytes
Kernel RAM usage	27 bytes
RAM usage per task control block	17 bytes
RAM usage per resource semaphore	4 bytes
RAM usage per counting semaphore	2 bytes
RAM usage per mailbox	11 bytes
RAM usage per software timer	9 bytes
RAM usage event	0 bytes
Min. stack-size per task (RAM)	45 bytes
Timing
Context switch time	208 µs
Interrupt latency time	49.5 µs
Kernel CPU usage/TICK	less than 1% of total calculation time at 1000 Interrupts/second (1ms TICK)
Basic time unit (TICK)	typ. 1 ms, min. 100 µs (10 kHz interrupt frequency)
Features
Max. no. of tasks	Unlimited (by available RAM only)
Max. no. of mailboxes	unlimited (by available RAM only)
Max. no. of semaphores (resource/binary/counting)	unlimited (by available RAM only)
Max. no. of software timers	unlimited (by available RAM only)
Max. no. of priorities	255
Stack size idle task (RAM)	0(no memory needed)
Nested interrupts	not supported
Task switches from within ISR	possible

Absolute timings given above were measured with embOS release build on an ST72F521 CPU running at 8MHz.
Note that task switch time depends on stack usage of a task.

embOSView offers system analysis during runtime

embOSView with ST72F521 CPU

Additional information

Release Notes embOS ST7 for COSMIC compiler