Get Start with TinyOS From technique perspective

1. Get Start with TinyOSFromtechnique perspective Tian He CS851 LSDEN

2. Road Map • TinyOS overview • How TinyOS works • Programming the mote • Programming environment guide

3. Application 2 Application 1 Application 1 NFS I/O Micro-kernel Monolith-kernel IPC Scheduler Scheduler VM I/O VM HW HW Traditional OS Architectures • Problem with Large Scale Deeply embedded system.. • Large memory & storage requirement • Unnecessary and overkill functionality ( address space isolation, • complex I/O subsystem , UI ) for our scenario. • Relative high system overhead ( e.g, context switch ) • Require complex and power consuming hardware support.

4. Which OS architecture we want • Extremely small footprint. • Extremely low system overhead. • Extremely low power consumption Only thing we need , nothing we don’t

5. Application Component Application Component Application Component TinyOS Architecture Overview (1) TinyOS Scheduler ……. I/O COMM . NO Kernel Direct hardware manipulation NO Process management Only one process on the fly. NO Virtual memory Single linear physical address space NO Dynamic memory allocation Assigned at compile time NO Software signal or exceptionFunction Call instead Goal: to strip down memory size and system overhead.

6. Actuating Sensing Active Message Communication TinyOS Architecture Overview (2) • Characteristic of TinyOS • No UI, power constrained • Unusually application specific HW and SW • Multiple flows, concurrency intensive bursts • Extremely passive vigilance ( power saving ) • Tightly coupled with the application. Main (includes Scheduler) Application (User Components) Simplified TinyOS Architecture Mote Hardware

7. Road Map • TinyOS overview • How TinyOS works • Programming the mote • Programming environment guide

8. How it works : Scheduling • Two-level scheduling ( Event and Task ) • Single shared stack ( used by both interrupt and function call) • Scheduler is simple FIFO with bounded number of pending task. • Task can NOT preempt each other. • Event has high priority than Task. Event can preempt task • Event can preempt each other , once enabled • When idle , scheduler shut down node except for clock

9. Simplified Main Loop int main() { TOS_CALL_COMMAND(MAIN_SUB_INIT)(); // initialize the subcomponents TOS_CALL_COMMAND(MAIN_SUB_START)(); //start the subcomponents while(1){ while(!TOS_schedule_task()) { }; //Run until no task in the FIFO Queue asm volatile ("sleep" ::); // save power } }

10. Scheduler in main function int TOS_schedule_task (){ TOS_sched_entry_T TOS_queue[MAX_TASK]; if (EMPTY) return -1; TOS_queue[TOS_sched_full].tp(); TOS_queue[TOS_sched_full].tp = 0; TOS_sched_full = (TOS_sched_full +1 == MAX_TASKS ) ? 0 : TOS_sched_full +1 } int TOS_post ( task_function_pointer) { if( FULL) return –1 ; //Post the associated task to the next free slot TOS_queue[TOS_sched_free ].tp = task_function_pointer; TOS_sched_free = (TOS_sched_free +1 == MAX_TASKS) ? 0 : TOS_sched_free +1 }

11. Event implementation Event is independent of FIFO scheduler. • Lowest level events are supported directly by Hardware interrupt • Software events propagate from lower level to upper level through function call. INTERRUPT(_output_compare2_){ // Hardware Timer Event Handler … TOS_SIGNAL_EVENT(CLOCK_FIRE_EVENT)( ); //Software Event … }

12. How it works: Sensor & Actuator Sensor stack Actuator stack Application LEDs Clock UART ADC RFM Application Clock Inter. LED interface PHOTO interface LED.c Clock.c PHOTO.c LED Hardware Timer ADC Hardware Sensor and actuator are achieved mainly through periodically polling

13. A simple profiling: If we want to send 60 Byte data, we need to invoke: Messaging layer 1 times Packet layer >2 times byte layer > 60 times RFM > 480 times Radio Packet How it works : Communication • Bit Encoding • Manchester encoding (1b 2b) • DC balancing (4b  6b) • SEC_DED forward error correction • (8b  17b) • Error detection & correction • SEC_DED Correct 1b Detect 2b • Signal strength • Each time a 1 bit is read in, • the ADC samples the value • of the BBOUT pin. • CSMA • Detect whether current channel • is free to transmit, otherwise wait • for random of clock ticks [12,75] • clock rate (10kHZ) LFSR One byte message type used to direct packet to handlers Real implementation: if(msg.type == 0) val = Handler0(data); if(msg.type == 1) val = Handler1(data); …. …. if(msg.type == 255) val = Handler255(data); User need to redefine handler name #define Handler1 XXXX #define Handler5 NULL_FUNC Application Component H2 H1 H3 Application • Packaging • Dividing/Combine • Routing • Echo ; Base_station Relay;…. • Special address • 0xff = Broadcast Address • 0x7E = UART interface • 30 Byte Fix length Packet • CRC check • 16 bit CRC check, • Drops packet if fails • Redundancy transmit • transmitted 3 times Content-based routing Consensus algorithm Location Service Tracking Sensor data processing …… …… AM Dispatcher messaging Simplex transceiver We can Set Operation Mode (TX/RX) Set Sampling Rate Receive one Bit Transmit one Bit Notify TX/RX is finished Shut down RFM (1/10th) Messaging packet Radio byte byte RFM bit

14. Road Map • TinyOS overview • How TinyOS works • Programming the mote • Programming environment guide

15. Graph of components = individual components + relations Individual components = command/event interface + behavior Behavior = Event + Command + Internal Tasks Programming the Mote (1) Program = graph of components + FIFO scheduler.

16. Internal Tasks Messaging Component Internal State Events Commands Programming the Mote (2) Individual component • Component interface (.comp) • Commands that it accepts(implemented) • Commands that it uses • Events that it signals • Events that it handles • Component implementation (.c) • Functions that implement interface • Frame: internal state • Tasks: internal concurrency • Uses only internal namespace A typical TinyOS component

17. Programming the Mote (3) Relations • Component dependence (.desc) • Glue the components • Denote the dependence among component. • Mapping the interface between the component. MAIN COUNTER CLOCK LEDS

18. Declare and access variable • TOS_FRAME_BEGIN, TOS_FRAME_END to declare a component frame example • VAR(foo) to access a variable (foo) in the frame TOS_FRAME_BEGIN(COUNTER_frame) { char state; } TOS_FRAME_END(COUNTER_frame); • Real implementation: • #define TOS_FRAME_BEGIN(frame_type) typedef struct • #define TOS_FRAME_END(frame_type) frame_type; • static frame_type TOS_MY_Frame; • #define VAR(x) TOS_MY_Frame.x

19. { ... status = TOS_CALL_COMMAND(name)(args) ... } Function call Function Call { ... status = TOS_SIGNAL_EVENT(name)(args) ... } { ... TOS_POST_TASK(name)(args) } Fun. Pointer FIFO Queue TinyOS Commands,Events and Tasks TOS_EVENT(name)(args) { ... return status; } TOS_COMMAND(name)(args) { ... return status; } TOS_TASK(name)(args) { ... return status; } Real implementation: #define TOS_COMMAND(command_name) TOS_CALL_COMMAND(command_name) #define TOS_EVENT(event_name) TOS_SIGNAL_EVENT(event_name)

20. UART Packet Radio Packet TinyOS Application by Composition • Application = graph of components + scheduler sensing application application Routing Layer routing Messaging Layer messaging packet Radio byte UART byte Temp byte photo SW HW RFM ADC i2c bit clocks

21. generic init interface MAIN clock interface main_sub_start main_sub_init output interface counter_init counter_start COUNTER counter_output clock_event counter_sub_clock_init counter_sub_output_init clock_init int_to_leds_init clock_fire_event int_to_leds_output CLOCK INT_TO_LEDS Composing applications from componentsSimple counter program .desc file describe the relationships between the component Interfaces are defined through .COMP File .c file implement the interface

22. Files for this simple application Seven Files • Describe the relation between compoents: • cnt_to_led.desc • Describe three components ( two files each) • Counter.c Counter.comp • Clock.c Clock.comp • INT_TO_LED.c INT_TO_LED.comp

23. MAIN main_sub_init counter_init Composing applications from componentsExample: apps/cnt_to_led.desc include modules{ MAIN; COUNTER; INT_TO_LEDS; CLOCK; }; MAIN:MAIN_SUB_INIT COUNTER:COUNTER_INIT MAIN:MAIN_SUB_START COUNTER:COUNTER_START COUNTER:COUNTER_CLOCK_EVENT CLOCK:CLOCK_FIRE_EVENT COUNTER:COUNTER_SUB_CLOCK_INIT CLOCK:CLOCK_INIT COUNTER:COUNTER_SUB_OUTPUT_INIT INT_TO_LEDS:INT_TO_LEDS_INIT COUNTER:COUNTER_OUTPUT INT_TO_LEDS:INT_TO_LEDS_OUTPUT COUNTER apps/cnt_to_led.desc

24. .comp component interface file TOS_MODULE COUNTER; ACCEPTS{ char COUNTER_START(void); char COUNTER_INIT(void); }; HANDLES{ void COUNTER_CLOCK_EVENT(void); }; USES{ //need following service provide by other component char COUNTER_SUB_CLOCK_INIT(char interval, char scale); char COUNTER_SUB_OUTPUT_INIT(); char COUNTER_OUTPUT(int value); }; SIGNALS{ // no signal it will generate }; To be implemented in .c file COUNTER.comp

25. Implemention: COUNTER.c #include "tos.h" #include "COUNTER.h" //Frame Declaration #define TOS_FRAME_TYPE COUNTER_frame TOS_FRAME_BEGIN(COUNTER_frame) { char state; } TOS_FRAME_END(COUNTER_frame); //Events handled /* Clock Event Handler: */ void TOS_EVENT(COUNTER_CLOCK_EVENT)(){ VAR(state) ++; TOS_CALL_COMMAND(COUNTER_OUTPUT)(VAR(state)); /*update LED state */ } COUNTER.c

26. COUNTER.c - rudimentary event processing //Commands accepted char TOS_COMMAND(COUNTER_INIT)(){ VAR(state) = 0; /* initialize output component */ return TOS_CALL_COMMAND(COUNTER_SUB_OUTPUT_INIT)(); } char TOS_COMMAND(COUNTER_START)(){ /* initialize clock component and start event processing */ return TOS_CALL_COMMAND(COUNTER_SUB_CLOCK_INIT)(tick2ps); }

27. Relationship description Cnt_to_rfm.desc Main.c sched.c MAIN Counter.c Counter.comp COUNTER Clock.c Clock.comp INT_TO_RFM.c INT_TO_RFM.comp INT_TO_RFM hardware.h am.c am.comp AM PACKETOBJ.c PACKETOBJ.comp PACKETOBJ CLOCK SEC_DED_RADIO_BYTE.c ...comp SEC_DED_RADIO_BYTE RFM.c ...comp RFM hardware.h More complicate example

28. Low level Mote Programming Detail • ATMEL 90S8535 can respond to 16 different interrupt sources. • Avr-gcc pre-defines interrupt symbols and interrupt jump table

29. Low level Mote Programming Detail To establish interrupt hander: 1. include the following headers in your C file #include "io-avr.h" #include "signal.h" #include "interrupt.h” 2. Write following subroutine: INTERRUPT(_uart_recv_) { ... } // Preemptive Event SIGNAL(_uart_recv_) { ... } //non-preemptive Event Alternative : sei() and cei() macros can enable and disable interrupt

30. SP Low level Mote Programming Detail Vector jump table (16)

31. Road Map • TinyOS overview • How TinyOS works • Programming the mote • Programming environment guide

32. Programming Environment • Lab Location: Olsson 018 • Platform: cygwin on top of Windows 2000 • Software: perl, gcc, java, atmel tools ,cygwin Mote-to-mote communication Program Code Mote-PC communication

33. Steps • Write Component ( .c and .comp file ) • Write Relation ( .desc file ) Run on Mote • Modify makefile • Set GROUP_ID • redefine Macro: DESC = XXXXX.desc • Build • Make clean ; make • Upload the image into Mote and run • Make install_windows Run on PC • Modify makefilePC • Build: make clean ; make -f makefilePC • Run: main < node_ID > • Details to upload Image to Mote • transcode your executable into Motorola S-record format: • avr-objcopy --output-target=srec ledblink ledblink.srec • erase the flash on the mote • uisp -dapa -dno-poll --erase • transfer the program to the mote • uisp -dapa -dno-poll --upload if=ledblink.srec • verify the flash • uisp -dapa -dno-poll --verify if=ledblink.srec

34. Programming & debug Tools • Makefile • Create super.h from DESC and COMP file, then link all component into one single image that is executable by ATMEL AVR AT90S2343 processor. • MakefilePC • It’s for debug purpose and run on the PC • gdb main <nod_ID> • Serial Port listener -- monitor traffic between mote and PC.

35. RF_Simulation Tools • Simulate Radio communication with ConnectionManager program • RFM and UART replaced by sockets • RFM connects to “127.0.0.1:9876” • UART connects to “127.0.0.1:8765” • add_conn(ID1, ID2) creates a bi-directional link between mote with ID1 and ID2 3 add_conn(1, 2);add_conn(2, 3);add_conn(3, 4);add_conn(4, 2); 1 2 4

36. Possible Project on Mote Test-Bed • Redesign the FIFO scheduler • Redesign MAC Layer from CSMA to …… • Ultra-Sound Device for location service ? • Distributed ConnectionManager for large scale Sim. • New Ad Hoc network algorithm • New application design (How to use mote novelty)

37. Related URL http://tinyos.millennium.berkeley.edu