Vendors of 32-bit microcontrollers were out in force at the Embedded Systems Conference in San Jose in April. So were real-time operating-system (RTOS) vendors eyeing this lucrative platform. Linux and many other operating systems simply don't fit on resource-constrained microcontrollers with a limited flash memory and SRAM, but a number of existing and new compact RTOSs do. And this market is getting crowded.
Express Logic's Threadx V5 offers a starting footprint that's under 6 kbytes of flash. It adds real-time performance metrics, run-time stack analysis, and built-in software trace support. A simplified timer interrupt and increased priority levels make the platform even more flexible. The new event-chaining feature allows a task to wait on a group of message queues. Royalty-free licenses start at $12,500.
CMX Systems has moved its CMX-RTX from CMX's usual 8- and 16-bit realm into the 32- and 64-bit world. The functionality is the same, and its footprint is on the order of 3.5 to 20 kbytes. CMX-Tiny+ is an even smaller, more limited RTOS. CMXRTX is only part of the puzzle, though. CMX's other protocol stacks and file systems also are available. Many of these can be used without an operating system. Royalty-free licenses start at $2200.
Green Hills Software's u-VelOSity is the little brother of VelOSity, which in turn is the basis for the high-end Integrity RTOS. u-VelOSity has a very small footprint, starting at 1.6 kbytes of flash and about 1 kbyte of SRAM. Its application programming interface (API) is upward-compatible with its siblings. Contact Green Hills Software for royalty-free pricing.
Quadros' RTXC also targets a range of platforms. Its dual-mode version is optimized for RISC/DSP microcontrollers. A single-project license starts at $15,500.
These small-footprint RTOSs provide only the minimal OS support, including task management, interprocess communication, and memory management. File systems, graphics, and communication protocol stacks are usually available for an additional charge and can significantly increase a system's footprint.
Green Hills Software