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A Quick Note on TinyOS Chris Merlin Group Meeting January 21 st, 2009
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Outline TinyOS: What Is It? TOSSIM, The TinyOS Simulator Dynamic Memory Allocation in TinyOS Concluding Remarks TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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TinyOS: A Quick Reminder A Simple and stripped down operating system for motes nesC language C Based For component-based programming Maybe a quarter million programmers in the world TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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(…2) TinyOS: A Quick Reminder Components: black boxes whose input and output functions are known (interfaces) Configurations: assemble other components together link interfaces used by components to providers Modules: Provide application code Use and provide interfaces TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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(…3) TinyOS: A Quick Reminder Consider a module called Application that needs to turn LEDs on and off The Leds interface provides functions to turn on/off, initialize, toggle LEDs Application would like to use that interface LedsC is a component that provides Leds interface Application.Leds -> LedsC.Leds; TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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Outline TinyOS: What Is It? TOSSIM, The TinyOS Simulator Dynamic Memory Allocation in TinyOS Concluding Remarks TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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TOSSIM: Generalities Simulator: Built with make pc Runs with DBG=[name], build/pc/main.exe [options] What it does: Displays traces Emulates mote+radio behavior What it doesn’t do: Model radio propagation Model power drain / energy consumption TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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Compiling and Running a Simulation Execute: build/pc/main.exe [options] num_nodes -b= : time over which motes boot -l= : runs sim. at times real time -r= : radio model: simple, static, lossy -rf= : input file for lossy model -t= : runs sim. for virtual seconds num_nodes : number of nodes TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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The Lossy Radio Model Input file can specify links’ bit error rates Lossy radio model can help create multi- hop networks of nodes : :ber TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS 0 0 11 1 1 1
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Outline TinyOS: What Is It? TOSSIM, The TinyOS Simulator Dynamic Memory Allocation in TinyOS Concluding Remarks TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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Dynamic Memory Allocation “TinyOS does not allow dynamic memory allocation” True: malloc will occasionally crash, realloc not supported on real motes False: malloc, realloc, free all work fine in TOSSIM. MemAlloc provides some DMA for real motes TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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Memory Model of TinyOS Simplicity of TinyOS allows only static mem. alloc (no management of dynamic heap) malloc must find space of appropriate size: can be resource consuming, esp. when mem. very fragmented TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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MemAlloc MemAlloc is provided by TinyAlloc Some commands are: allocate(HandlePtr hptr, int size) : allocate memory region of size reallocate(Handle h, int size) free(Handle h) However, MemAlloc is split-phase Events: allocComplete(HandlePtr hptr, result_t outcome) : indicate an allocation has completed reallocComplete(Handle h, result_t outcome) TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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MemAlloc Example TinyAlloc implements managed heap: simple array of handles Memory regions are referenced indirectly by another array Double dereferencing is needed TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS Handle array; call MemAlloc.allocate(&array, 2*sizeof(ArrayEntry)); ArrayEntry *entry = (ArrayEntry*)(*array+sizeof(ArrayEntry))
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Outline TinyOS: What Is It? TOSSIM, The TinyOS Simulator Dynamic Memory Allocation in TinyOS Concluding Remarks TinyOS: What is it?TOSSIM, the TinyOS SimulatorDynamic Memory Allocation in TinyOS
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Remarks If you have suggestions, pieces of code to add, let me know Compiled in Tutorial on WCNG website / my Academic page
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