TinyOS: Key Concepts

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TinyOS Key Concepts

• Charley Robinson
• Presented to the Group of Robotics, External
  Monitoring, and Little Networked Systems
• (GREMLNS)?

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TinyOS vs. Embedded C

• TinyOS is implemented in nesC
• Component based programming
• Interface defined behavior
• Event driven runtime
• No heap

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A C(ish) Light Blinking Program
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How nesC does it
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nesC Blink Configuration
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Components, Interfaces, Commands Events

• A component may be both a provider and a user of
  any number of interfaces.
• Interfaces, therefore, are bi-directional. An
  interface may have any number of commands and
  events.
• Commands will be implemented by a providing
  component, and called by user.
• Events will be implemented by a using component,
  and signaled by provider.

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Previous Slide as a Picture

• TimerComponent provides StdCtrl, Timer.
• TimerComponent uses Clock.
• Picture Credit Karl, Willig, 2005. Protocols and
  Architectures for Wireless Sensor Networks.

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Tasks

• Commands and Event handlers are synchronous,
  unless explicitly stated otherwise.
• Long running commands or events can cause other
  event signals to be missed entirely.
• Tasks are asynchronous jobs that can be scheduled
  after the current call stack returns.
• Posted tasks are executed FIFO.

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Split-Phase Command Processing

• Since TinyOS does not have any blocking
  operations, long-running commands are
  split-phase.
• Commands are issued and return immediately,
  events handle command completion some time later.
• This allows multiple commands to be issued in
  parallel without consuming much stack space.

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Blocking vs. Split-Phase Operations
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A More Complex Example

• module ForwarderP
• uses interface Boot,
• interface Receive as ReceiveMsg
• interface AMSend as SendMsg
• interface SplitControl as MsgCtrl
• implementation
• IntMsg_t buf message_t packet
• event void Boot.booted()
• call MsgCtrl.start()
• return SUCCESS
• event void MsgCtrl.startDone() ...
• event void MsgCtrl.stopDone() ...
• event message_t ReceiveMsg.receive(message_t
  msg, void payload, uint8_t len)
• call Leds.yellowToggle()
• memcpy(buf, payload, sizeof(IntMsg_t))
• post processPacket()
• return m

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Structures and Configuration
intmsg.h typedef nx_struct IntMsg_t
nx_uint16_t accumulator IntMsg_t enum
INTMSG_AM_ID 0x77 -- ForwarderC.nc configu
ration ForwarderC implementation
components ForwarderP as App components
MainC, ActiveMessageC components new
AMSender(INTMSG_AM_ID) components new
AMReceiver(INTMSG_AM_ID) App. SendMsg -gt
AMSender.Send App.ReceiveMsg -gt AMReceiver
App.MsgCtrl -gt ActiveMessageC App.Boot -gt
MainC
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Relevant Interfaces
interface Boot event void Booted() interface
AMSend command error_t send(am_addr_t addr,
message_t msg, uint8_t len) command void
getPayload(message_t msg, uint8_t
len) ... event void sendDone(message_t msg,
error_t error) interface Receive event
message_t receive(message_t msg ,void payload,
uint8_t len) interface SplitControl command
error_t start() command error_t stop() event
void startDone(error_t error) event void
stopDone(error_t error)
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More Resources

• TinyOS Tutorialshttp//docs.tinyos.net/index.php
  /TinyOS_Tutorials
• TinyOS Reference Documentationhttp//docs.tinyos
  .net/index.php/Source_Code_Documentation
• TinyOS TEP Papershttp//docs.tinyos.net/index.ph
  p/TEPs
• TinyOS Programming Manualhttp//www.tinyos.net/t
  inyos-2.x/doc/pdf/tinyos-programming.pdf
• ...and so much more
• http//www.tinyos.net/