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A TinyOS Sensor Application called MyApp. Objectives How to create a simple Mote firmware application that reads light sensor data from your sensor board How to send a message containing the sensor data through the Mote serial port connected directly to the programming board. - PowerPoint PPT Presentation
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Feb 2007WSN Training: Creating a Simple Sensor Application 1
A TinyOS Sensor Application called MyApp
Objectives How to create a simple Mote firmware application
that reads light sensor data from your sensor board How to send a message containing the sensor data
through the Mote serial port connected directly to the programming board
WSN Training: Creating a Simple Sensor Application
2 Feb 2007
Required Hardware and PC Setup
1. Two MICA Motes: standard editions of MICA2 (MPR4x0) or MICAz (MPR2600) or OEM editions of MICA2 or MICAz
2. One sensor or data acquisition board: MDA100, MTS300 or MTS310
3. One gateway board: MIB510, MIB520, or MIB600 and the associated hardware (cables, power supply) for each
4. A Windows PC with MoteWorks installed
The steps that you’ll take to build the application will be as follows:
Build (compile) and download the application Take a closer look at the code and auxiliary files
WSN Training: Creating a Simple Sensor Application
3 Feb 2007
About sensor application MyApp
What does MyApp do? It is a simple sensing application that samples the light sensor—
the photodetector—on a sensor board, packetizes the data, and sends the data back to the base station.
What am I expected to learn? This exercise is intended to is presented here to help further
familiarize you with nesC programming and TinyOS messaging.
What is different from the app MyApp in lesson_1 ? Take light readings using one of the following sensors boards:
MTS300/310 or MDA100 Use the Mote serial port (UART) and radio to send sensor data to
the base station Blink the green LED when the sensor is sampled Blink the yellow LED when the sensor data message is
successfully sent to the base station Compile and debug if necessary
WSN Training: Creating a Simple Sensor Application
4 Feb 2007
MyApp Application Review
The application folder (directory) is where all your top-level application code and associated files will be stored. 1. Navigate to the directory
/MoteWorks/apps/tutorials/lesson_ 2
2. The Makefile and Makefile.component are exactly the same as the MyApp of lesson_1 application so we will move along to the configuration and module files.
WSN Training: Creating a Simple Sensor Application
5 Feb 2007
Sensor Application MyApp_Sensor
What’s new? The sensorboardsApp.h file
What is it used for? Define packet structure
Defines the XSensor header Defines the sensor data payload So you can understand what the bytes mean in a serial
data stream
Defines the default values for critical fields SENSOR_BOARD_ID “Tags” the packet so XServe can identify what application
sent it. Sensor data packets are put into the proper database table
or flat file by XServe
Feb 2007WSN Training: Creating a Simple Sensor Application 6
MyApp
Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes nesC Auto documentation
WSN Training: Creating a Simple Sensor Application
7 Feb 2007
MyApp – Makefile.component
Specify the sensorboard in the Makefile.component fileFor example, the Makefile.component for MyApp is
What does this do? Tells the nesC compiler to link in all the TinyOS components
(drivers) required to access the sensors on the MTS310 sensorboard.
Drivers for the MTS310 sensorboard are located in the /MoteWorks/tos/sensorboards/mts310 folder.
NOTE: There are drivers for other sensorboards located in under /MoteWorks/tos/sensorboards.
COMPONENT=MyAppSENSORBOARD=mts310
Feb 2007WSN Training: Creating a Simple Sensor Application 8
Review: MyApp
Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes nesC Auto documentation
WSN Training: Creating a Simple Sensor Application
9 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For code that is reachable from at least one interrupt
atomic For a block of code that runs interrupted to prevent race conditions
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
10 Feb 2007
/MoteWorks/apps/tutorials/lesson_2/MyApp.nc Configuration – Sampling the Light Sensor
includes sensorboardApp;
/** * This module shows how to use the Timer, LED, ADC and Messaging * components. * Sensor messages are sent to the serial port**/configuration MyApp {}implementation { components Main, MyAppM, TimerC, LedsC, Photo, GenericComm as Comm; Main.StdControl -> TimerC.StdControl; Main.StdControl -> MyAppM.StdControl; Main.StdControl -> Comm.Control; MyAppM.Timer -> TimerC.Timer[unique("Timer")]; MyAppM.Leds -> LedsC.Leds; MyAppM.PhotoControl -> Photo.PhotoStdControl; MyAppM.Light -> Photo.ExternalPhotoADC; MyAppM.SendMsg -> Comm.SendMsg[AM_XSXMSG];}
NEW! The Photo component is used to actuate the sensorboard photo sensor device.
NEW! The GenericComm component is used to send messages over the serial port and radio.
WSN Training: Creating a Simple Sensor Application
11 Feb 2007
MyApp.nc Configuration – Sampling the Light Sensor
includes sensorboardApp;
/** * This module shows how to use the Timer, LED, ADC and Messaging * components. * Sensor messages are sent to the serial port**/configuration MyApp {}implementation { components Main, MyAppM, TimerC, LedsC, Photo, GenericComm as Comm; Main.StdControl -> TimerC.StdControl; Main.StdControl -> MyAppM.StdControl; Main.StdControl -> Comm.Control; MyAppM.Timer -> TimerC.Timer[unique("Timer")]; MyAppM.Leds -> LedsC.Leds; MyAppM.PhotoControl -> Photo.PhotoStdControl; MyAppM.Light -> Photo.ExternalPhotoADC; MyAppM.SendMsg -> Comm.SendMsg[AM_XSXMSG];}
The Photo component implements the StdControl interface for turning on and off the light sensor and the ADC interface for sampling the sensor value through the hardware ADC port.
WSN Training: Creating a Simple Sensor Application
12 Feb 2007
MyApp.nc Configuration – Sampling the Light Sensor
includes sensorboardApp;
/** * This module shows how to use the Timer, LED, ADC and Messaging * components. * Sensor messages are sent to the serial port**/configuration MyApp {}implementation { components Main, MyAppM, TimerC, LedsC, Photo, GenericComm as Comm; Main.StdControl -> TimerC.StdControl; Main.StdControl -> MyAppM.StdControl; Main.StdControl -> Comm.Control; MyAppM.Timer -> TimerC.Timer[unique("Timer")]; MyAppM.Leds -> LedsC.Leds; MyAppM.PhotoControl -> Photo.PhotoStdControl; MyAppM.Light -> Photo.ExternalPhotoADC; MyAppM.SendMsg -> Comm.SendMsg[AM_XSXMSG];}
• MyAppM.PhotoControl (StdControl interface) to the Photo.PhotoStdControl (StdControl interface for the light sensor)
• The MyAppM.Light (ADC interface) to the Photo.ExternalPhotoADC (ADC interface for light sensor).
WSN Training: Creating a Simple Sensor Application
13 Feb 2007
MyApp.nc Configuration – Sampling the Light Sensor
includes sensorboardApp;
/** * This module shows how to use the Timer, LED, ADC and Messaging * components. * Sensor messages are sent to the serial port**/configuration MyApp {}implementation { components Main, MyAppM, TimerC, LedsC, Photo, GenericComm as Comm; Main.StdControl -> TimerC.StdControl; Main.StdControl -> MyAppM.StdControl; Main.StdControl -> Comm.Control; MyAppM.Timer -> TimerC.Timer[unique("Timer")]; MyAppM.Leds -> LedsC.Leds; MyAppM.PhotoControl -> Photo.PhotoStdControl; MyAppM.Light -> Photo.ExternalPhotoADC; MyAppM.SendMsg -> Comm.SendMsg[AM_XSXMSG];}
•This wires the XSensor channel of GenericComm into the application’s send interface.
•This wires the XSensor channel of GenericComm into the application’s send interface.
Feb 2007WSN Training: Creating a Simple Sensor Application 14
Review: MyApp
Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes View data via XServe
WSN Training: Creating a Simple Sensor Application
15 Feb 2007
Creating the Top Level Module
The application’s module is located in the MoteWorks/apps/tutorials/lesson_2/MyAppM.nc file.
How does this module differ from MoteWorks/apps/tutorials/lesson_1/MyAppM.nc? This new module differs from the
MoteWorks/apps/tutorials/lesson_1/MyAppM.nc module in that it adds the functionality of sampling the light sensor when the timer fires
Then a sensor message is sent through the Mote’s serial (UART) port when the sampling is complete.
(Radio communications will be done in the another session)
WSN Training: Creating a Simple Sensor Application
16 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For code that is reachable from at least one interrupt
atomic For a block of code that runs interrupted to prevent race conditions
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
17 Feb 2007
MyAppM.nc – Specification
includes sensorboardApp;/** * This module shows how to use the Timer, LED, ADC and Messaging * components * Sensor messages are sent to the serial port **/module MyAppM { provides { interface StdControl; } uses { interface Timer; interface Leds; interface StdControl as PhotoControl; interface ADC as Light; interface SendMsg;
}}
• Hardware specific definitions for the MTS300/310.
• Located in the application directory
• Hardware specific definitions for the MTS300/310.
• Located in the application directory
WSN Training: Creating a Simple Sensor Application
18 Feb 2007
implementation { bool sending_packet = FALSE; TOS_Msg msg_buffer; XDataMsg *pack; /** * Initialize the component. * * @return Always returns <code>SUCCESS</code> **/ command result_t StdControl.init() { call Leds.init(); call PhotoControl.init(); // Initialize the message packet with default values atomic { pack = (XDataMsg *)&(msg_buffer.data); pack->xSensorHeader.board_id = SENSOR_BOARD_ID; pack->xSensorHeader.packet_id = 2; pack->xSensorHeader.node_id = TOS_LOCAL_ADDRESS; pack->xSensorHeader.rsvd = 0;}
return SUCCESS; }
MyAppM.nc – Implementation
WSN Training: Creating a Simple Sensor Application
19 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For code that is reachable from at least one interrupt
atomic For a block of code that runs interrupted to prevent race conditions
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
20 Feb 2007
atomic Keyword (Review)
atomic keyword is used to denote a block of code that runs uninterrupted (interrupts disabled) Prevents race conditions
When should it be used? Required to update global variables that are referenced
in async event handlers Must use atomic block in all other functions and tasks
where variable is referenced
nesC compiler with generate warning messages for global variables that need atomic blocks Example:
SensorAppM.nc:44: warning: non-atomic accesses to shared variable ‘voltage’
WSN Training: Creating a Simple Sensor Application
21 Feb 2007
nesC Interface -- ADC
interface ADC { async command result_t getData(); async command result_t getContinuousData(); async event result_t dataReady(uint16_t data);}
The ADC interface is specified with two commands: getData getContinuousData
and one event dataReady
What to do to sample the thermistor sensor? call the getData command
This will start a process of sampling the light sensor through the processor hardware ADC interface
At some later time this process will complete and receive the current light sensor value through the dataReady event
WSN Training: Creating a Simple Sensor Application
22 Feb 2007
Sample Sensor and Call Back with Value
event result_t Timer.fired() { call Leds.redToggle();
call PhotoControl.start();call Light.getData();
… async event result_t Light.dataReady(uint16_t data) {
atomic pack->xData.datap1.light = data; atomic pack->xData.datap1.vref = 417; // a dummy 3V reference voltage, 1252352/3000 = 417 post SendData();
call Leds.yellowToggle();…
1. The Timer.fired() event function we first turn on the light sensor by calling the start() command through the StdControl interface. The red LED will blink (“heartbeat”) when this happens.
2. Next we call the getData() command through the ADC interface to start the process of sampling the current tvalue.
3. At some time in the near future when the sampling has completed we then receive a callback in the form of a dataReady() event.
1
2 3
WSN Training: Creating a Simple Sensor Application
23 Feb 2007
Sample Sensor and Call Back with Value
event result_t Timer.fired() { call Leds.redToggle();
call PhotoControl.start();call Light.getData();
… async event result_t Light.dataReady(uint16_t data) {
atomic pack->xData.datap1.light = data; atomic pack->xData.datap1.vref = 417; // a dummy 3V reference voltage, 1252352/3000 = 417 post SendData();
call Leds.yellowToggle();…
4. The dataReady() event passes the 16-bit (10 significant bits) photodetector value that we store in our message packet for sending later.
5. The last thing we do is to post a task (a split-phase operation) to send a message containing the sensor data and fire the yellow LED
45
WSN Training: Creating a Simple Sensor Application
24 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For code that is reachable from at least one interrupt
atomic For a block of code that runs interrupted to prevent race conditions
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
25 Feb 2007
Split-Phase -- Request & Done Sequence
Event handler
Component1
goCmdX{…post task1();return SUCCESS}
commandA {…call Comp2.goCmdX;//continuereturn SUCCESS}
Non-blocking commands initiate an operation Continue/idle Event indicates completion at some future time
Task1{//do stuffsignal cmdXDone();return SUCCESS}
event cmdXDone{//process result…return SUCCESS} TOS Scheduler
Component2
WSN Training: Creating a Simple Sensor Application
26 Feb 2007
When to Use Split-Phase
Variable duration processes Hardware I/O operations
ADC start conversion –> Data Ready
Slow devices Flash memory, Write buffer –> Done
Asynchronous or Complex Processes Send a message to communications stack and continue
with operations until .sendDone
WSN Training: Creating a Simple Sensor Application
27 Feb 2007
Sending a Message Packet – GenericComm
How to send a packet of data to the outside world? Use the TinyOS communication component named GenericComm.
GenericComm is able to send packets in two ways The UART port or Over the radio
How is that specified? The destination node address specified Reserved node addresses
Broadcast 0xFFFF UART Channel0x007E
Otherwise send directly to a specific node ID in it’s RF neighborhood
WSN Training: Creating a Simple Sensor Application
28 Feb 2007
MoteWorks/apps/tutorials/lesson_2/MyApp.nc Configuration Revisited
implementation { components Main, MyAppM, TimerC, LedsC, Photo, GenericComm as Comm; Main.StdControl -> TimerC.StdControl; Main.StdControl -> MyAppM.StdControl; Main.StdControl -> Comm.Control; … MyAppM.SendMsg -> Comm.SendMsg[AM_XSXMSG];…
The GenericComm (aliased as Comm) is connected through its Comm.Control (StdControl) interfaceThe MyAppM module connects to one instance of the Comm.SendMsg interface.The AM_XSXMSG identifies the active message type.
This value is used to distinguish between multiple messages you may wish to send.
WSN Training: Creating a Simple Sensor Application
29 Feb 2007
nesC Interface -- SendMsg
interface SendMsg{ command result_t send(uint16_t address, uint8_t length, TOS_MsgPtr msg); event result_t sendDone(TOS_MsgPtr msg, result_t success);}
The SendMsg interface specifies one command Send
and one event sendDone
To send a message call the send command with the correct parametersA sendDone event is received after the message has been sent
WSN Training: Creating a Simple Sensor Application
30 Feb 2007
nesC Interface -- SendMsg
interface SendMsg{ command result_t send(uint16_t address, uint8_t length, TOS_MsgPtr msg); event result_t sendDone(TOS_MsgPtr msg, result_t success);}
Each message that is sent using the SendMsg interface is defined by a data structure named TOS_Msg
WSN Training: Creating a Simple Sensor Application
31 Feb 2007
nesC Data Structure -- TOSMsg
typedef struct TOS_Msg{ /* The following fields are transmitted/received on the radio. */ uint16_t addr; uint8_t type; uint8_t group; uint8_t length; int8_t data[TOSH_DATA_LENGTH];}typedef TOS_Msg *TOS_MsgPtr;
addr – the destination address type – the active message type (for this application it is AM_XSXMSG)
group – group id specified during programming length – the payload length data – variable length payload area (sensor data)
WSN Training: Creating a Simple Sensor Application
32 Feb 2007
MoteWorks/apps/tutorials/lesson_2/MyAppM.nc – Application Data Payload command result_t StdControl.init() {… // Initialize the message packet with default values atomic { pack = (XDataMsg *)&(msg_buffer.data); pack->xSensorHeader.board_id = SENSOR_BOARD_ID; pack->xSensorHeader.node_id = TOS_LOCAL_ADDRESS; pack->xSensorHeader.rsvd = 0;
}…
The data region in the TOS_Msg is where we place our application specific payload.
The code excerpt above is from the MoteWorks/apps/tutorials/lesson_2/MyAppM.nc module that shows how we initialize the payload area of the TOS_Msg for our specific sensor application
WSN Training: Creating a Simple Sensor Application
33 Feb 2007
void task SendData() { call PhotoControl.stop();
if (sending_packet) return; atomic sending_packet = TRUE;
// send message to UART (serial) portif (call
SendMsg.send(TOS_UART_ADDR,sizeof(XDataMsg),&msg_buffer) != SUCCESS)
sending_packet = FALSE;… event result_t SendMsg.sendDone(TOS_MsgPtr msg, result_t success) {
call Leds.greenToggle();atomic sending_packet = FALSE;
…
Notice first how the sendData task calls the stop command for the light sensor component.This is done in order to save power when we are not using the sensor.
If we are currently in the process of sending a message (sending_packet = TRUE) we just return. This means the sendDone event has yet to be called and we must wait.
MoteWorks/apps/tutorials/lesson_2/MyAppM.nc – Application Data Payload
WSN Training: Creating a Simple Sensor Application
34 Feb 2007
void task SendData() { call PhotoControl.stop();
if (sending_packet) return; atomic sending_packet = TRUE;
// send message to UART (serial) portif (call
SendMsg.send(TOS_UART_ADDR,sizeof(XDataMsg),&msg_buffer) != SUCCESS)
sending_packet = FALSE;… event result_t SendMsg.sendDone(TOS_MsgPtr msg, result_t success) {
call Leds.greenToggle();atomic sending_packet = FALSE;
…
We call the SendMsg.send command passing the destination node address, in this case TOS_UART_ADDR and a pointer to the actual message packet we wish to send.
MoteWorks/apps/tutorials/lesson_2/MyAppM.nc – Application Data Payload
WSN Training: Creating a Simple Sensor Application
35 Feb 2007
void task SendData() { call PhotoControl.stop();
if (sending_packet) return; atomic sending_packet = TRUE;
// send message to UART (serial) portif (call
SendMsg.send(TOS_UART_ADDR,sizeof(XDataMsg),&msg_buffer) != SUCCESS)
sending_packet = FALSE;… event result_t SendMsg.sendDone(TOS_MsgPtr msg, result_t success) {
call Leds.greenToggle();atomic sending_packet = FALSE;
…
Finally the SendMsg.sendDone event is called notifying us the packet has been sent.We are now ready to start the whole process over again the next time the timer fires.
MoteWorks/apps/tutorials/lesson_2/MyAppM.nc – Application Data Payload
WSN Training: Creating a Simple Sensor Application
36 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For code that is reachable from at least one interrupt
atomic For a block of code that runs interrupted to prevent race conditions
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
37 Feb 2007
atomic Keyword (Review)
atomic keyword is used to denote a block of code that runs uninterrupted (interrupts disabled) Prevents race conditions
When should it be used? Required to update global variables that are referenced
in async event handlers Must use atomic block in all other functions and tasks
where variable is referenced
nesC compiler with generate warning messages for global variables that need atomic blocks Example:
SensorAppM.nc:44: warning: non-atomic accesses to shared variable ‘voltage’
WSN Training: Creating a Simple Sensor Application
38 Feb 2007
Fan-Out
Component is wired to multiple DestinationsCommands and Events will flow between all
connected componentsOrder is not guaranteed
configuration CntToLedsAndRfm {}implementation { components Main, Counter, IntToLeds, IntToRfm, TimerC; Counter.IntOutput -> IntToLeds; Counter.IntOutput -> IntToRfm;}
Tinyos-1.x/apps/CntToLedsAndRfm.nc
WSN Training: Creating a Simple Sensor Application
39 Feb 2007
nesC Keywords – Implementation
Basic implementation keywords
call Execute a command
signal Execute an event
post Put a task on the execution queue
task A function to be executed in the background
includes Include a header file
Support for automatic prevention of race conditions
async For commands, events executed asynchronously
atomic For commands, events executed asynchronously
norace Eliminates warnings of race conditions nesC detected
WSN Training: Creating a Simple Sensor Application
40 Feb 2007
norace Keyword
NesC compiler will sometimes generate warning messages for global variables that cannot produce race conditions
Warnings can be disabled for a particular variable using the norace keyword Example: norace uint16_t voltage;
WSN Training: Creating a Simple Sensor Application
41 Feb 2007
QUIZ
1. What type of events do hardware interrupts generate?
2. What is a race condition and how is this prevented?
3. Can tasks be interrupted?4. How are tasks processed by the scheduler?5. What is split-phase processing and why is it
important?6. What is special about atomic code?
Feb 2007WSN Training: Creating a Simple Sensor Application 42
Review: MyApp
Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes nesC Auto documentation lab
WSN Training: Creating a Simple Sensor Application
43 Feb 2007
MyApp – Compile and Install Program
1. Compile the MyApp sensor application2. Install program (“flash”) a Mote3. Watch the LED pattern. What is happening?
You should see the red, green and yellow LED’s blinking every second.
LED color
Indication
Red 1 second timer event fired
Yellow Light sensor has been sampled
Green Sensor message has been sent back to base station
WSN Training: Creating a Simple Sensor Application
44 Feb 2007
Lab
Challenge exercise Make the sensor application read both the
photodetector in addition to thermistor on the MTS300/310 or MDA100.
When the photodetector is covered, make the red LED blink twice per second
When the photodetector is not covered, make the red LED stay on constantly
See WSN Training CD for one answer. In the “Challenge_apps” directory
Feb 2007WSN Training: Creating a Simple Sensor Application 45
Q & A: Reviewing a TinyOS Sensor Application called MyApp
Objectives How to create a simple Mote
firmware application that reads light sensor data from your sensor board
How to send a message containing the sensor data through the Mote serial port connected directly to the programming board
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