Queue sets and tickless idle added in new version of FreeRTOS

February 20, 2013

Toni_McConnel-February 20, 2013

Real Time Engineers Ltd. has released V7.4.0 of its FreeRTOS. The new verision adds queue set functionality and enhanced support for tickless low power operation.

Queue sets enable an RTOS task to block (pend) when receiving from multiple queues and/or semaphores at the same time. Queues and semaphores are grouped into sets, then, instead of blocking on an individual queue or semaphore, a task instead blocks on the set.

The FreeRTOS tickless idle mode stops the periodic tick interrupt during idle periods (periods when there are no application tasks that are able to execute), then makes a correcting adjustment to the RTOS tick count value when the tick interrupt is restarted. Stopping the tick interrupt allows the microcontroller to remain in a deep power saving state until either an interrupt occurs, or it is time for the RTOS kernel to transition a task into the Ready state.

FreeRTOS also features a tiny, fully thread aware and re-entrant UDP/IP stack. The UDP/IP stack provides both a standard and zero copy Berkeley sockets-like interface in about 6Kbytes of code.

More information: queue set functionality, tickless low power operation

Toni McConnel can be reached at

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