1 lab4 objectives learn to read light sensor data from sensor board learn to transmit a message...

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Lab4

Objectives Learn to read light sensor data from sensor board

Learn to transmit a message containing the sensed data

through Mote serial port (UART) connected directly to the programming board

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Required Hardware and PC Setup

1. Two MICA Motes: standard editions of MICA2 (MPR4x0) or MICAz (MPR2600)

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

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MyApp Application Review

Under the directory /MoteWorks/apps/tutorials/lesson_ 2

The Makefile and Makefile.component are exactly the same as the MyApp of lesson_1.

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About MyApp

What does MyApp do? a simple sensing application that samples the light sensor

(photodetector) on a sensor board, packetizes the data, and sends the data back to the base station.

How does it differ from the application in lesson_1 ? Take light readings using sensors boards Use the Mote serial port (UART) 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

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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

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MyApp

Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes nesC Auto documentation

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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

Note: we’ll need to use SENSORBOARD=mda100cb

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Review: MyApp


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/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 or radio.

Include a header file

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MyApp.nc Configuration – Sampling the Light Sensor



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.

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• 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).

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•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.

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Review: MyApp


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Top Level Module

Located in MoteWorks/apps/tutorials/lesson_2/MyAppM.nc

How does this module differ from MoteWorks/apps/tutorials/lesson_1/MyAppM.nc? 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.

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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

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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

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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

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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 will generate warning messages for global variables that need atomic blocks Example:

SensorAppM.nc:44: warning: non-atomic accesses to shared variable ‘voltage’

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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 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

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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. In 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 value.

3. At some time in the near future when the sampling has completed, we receive a callback in the form of a dataReady() event.

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2 3

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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.

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

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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

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When to Use Split-Phase

Variable duration processes Hardware I/O operations

e.g., ADC start conversion –> Data Ready

Slow devices e.g., Flash memory, Write buffer –> Done

Asynchronous or Complex Processes Send a message to communications stack and continue

with operations until sendDone

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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? Through destination node address Reserved node addresses

Broadcast 0xFFFF UART Channel0x007E

Otherwise send directly to a specific node ID in it’s RF neighborhood

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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.

It is used to distinguish between multiple messages you may wish to send.

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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 parameters A sendDone event is received after the message has been sent

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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

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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)

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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

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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

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sending_packet = FALSE;… event result_t SendMsg.sendDone(TOS_MsgPtr msg, result_t success) {


…

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.


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sending_packet = FALSE;…} event result_t SendMsg.sendDone(TOS_MsgPtr msg, result_t success) {


…}

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.


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Review: MyApp

Steps Makefile Makefile.component Top-level application configuration Top-level module Compile app and flash Motes nesC Auto documentation lab

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MyApp – Compile and Install Program

1. Compile the MyApp sensor application2. Install program to (“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

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nesC Auto documentation

Follow steps stated in Lab 1

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What you need to do?

Finish Lab4 (posted in HuskyCT)

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1 lab4 objectives learn to read light sensor data from sensor board learn to transmit a message...

Documents

sensor application myapp

sensor board

light sensor data

myapp makefile

sensor data message

sensor messages

sensor data packets

sensor data payload