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++ Next: Linux Target + Up: Understanding Canfestival + Previous: CanFestival CAN interfaces + Contents +
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++As exemples, periodic sync emission, heartbeat production or SDO timeout +need to set some alarms that will be called later and do the job. + +
+µC generaly do not have enough free timers to handle all the +CanOpen needs directly. Moreover, CanFestival internal data may be +corrupt by reentrant calls. + +
+CanFestival implement a micro-scheduler (timer.c). It uses only one +timer to mimic many timers. It manage an alarm table, and call alarms +at desired time. + +
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++Scheduler can handle short clock value ranges limitation found on some +µC. As an example, value range for a 16bit clock counter with +4µs tick is crossed within 0.26 seconds... Long alarms must be +segmented. + +
+Chronogram illustrate a long alarm (A) and a short periodic alarm (B), +with a A value > clock range > B value. +Values t0...t8 are successive setTimer call parameter values. t1 +illustrates an intermediate call to TimeDispatch, caused by a delay +longer than clock range. Because of long alarm segmentation, at the end +of t1, TimeDispatch call will not trig any alarm callback. + +
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