opentag webinar3

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8/11/2019 opentag webinar3

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OpenTag: Office Hours

JP Norair

12 May 2011

skype: jpnorair

OpenTag: Office Hours

JP Norair

12 May 2011

skype: jpnorair

!Some information about DAS!What you get [with OpenTag]

!Where to get it

!What you can do to help

!Project Roadmaps! Answering your Questions

DASH7 Mode 2 is a 2nd Generation WSN/IoT/RFID Technolo

Mode 2

About DASH7 Alliance

• Specification Development

! Mode 2 (basically done)! “DNA” Middleware layer

! NFC integration

! More

• Market Development

• ISO Stewardship

• Go to dash7.org to see new membership

terms, and other information.

What You Get [with OpenTag]OpenTag is a very purpose-built OS that uses DASH7 I/O

OpenTag Component What it Does

Low Level Radio Driver PHY & MAC Control

System Event and Session Manager (OS-like)

Network Protocols (M2NP, M2DP, M2AdvP) Routing, Raw Data, Group Synchr

Transport Protocols (M2QP) Query / Data Acquisition, Data T

Filesystem Read, Write, Create, Delete,

Application Modules Built-in Apps (none yet)

C API Library functions (Programming apps in C o

Serial API(s) Client-Server (Communicating the apps via

Where to Get it

http://sourceforge.net/projects/open

git clone git://opentag.sourceforge.net/gitroot/ope

http://www.indigresso.com/wiki

How You Can Help

• Currently about 3 Beta testers

(you know who you are: if you

want to be recognized, email me)

• Download the code, compile,

and play with it. You will find

bugs and have questions.

! Send messages on developers

mailing list (sourceforge).

! Skype me, for quick info

How You Can Help

• Currently just me (officially)

• Requires a good understanding

of the code and specification

! My estimation: will take you

3-6 weeks to get here

• Two possibilities

! OT library development

! Porting to other platforms

How You Can Help

• Currently just me (officially)

• Requires a good understanding

of the code and specification

! My estimation: will take you

3-6 weeks to get here

• Two possibilities

! OT library development

! Porting to other platforms

• Currently just m

• Requires a goo

of the code or s

• Many possibilit

! Wiki

! Formal docum

! Academic res

Feature Roadmap: Now it is a Race

position

Planned Platform Supp

Case Studies (Comprehensive Answers to Recently Asked Q

!How does OpenTag enable location derivation?

!Can OpenTag do multihop and mesh?

!How are events processed?

!How many simultaneous connections are supported?

!How is data stored and logged?

!What is the deal with wireless regulations at 433 MHz?

How does OpenTag

enable location derivation?

DASH7 Mode 2 Has Two Features that Enable Location DerivFeature 1: Normalized RSSI

Open Loop Closed Loop

DASH7 Mode 2 Foreground Frame Architecture

DASH7 Mode 2 Has Two Features that Enable Location Deriv(2) Buferring Location Data

Location Coordinate

coord N

coord 3

coord 2

coord 1

Location List

DASH7 Mode 2 Has Two Features that Enable Location Deriv(2) Buferring Location Data

Location Coordinate

coord N

coord 3

coord 2

coord 1

Location List

OpenTag Implements Normalized RSSI

DASH7 LocationFeatures

Normalized RSSI

Angle of Incidence

Requires special HW, not

currently tested or

implemented in OpenTag

RSSI is imp

Driver. Dur

OpenTag b

normalized

antenna (ty

by calling r

Normalized RSSI

Angle of Incidence

currently tested or

RSSI is imp

Driver. Dur

OpenTag b

normalized

antenna (ty

by calling r

Normalized RSSI

Angle of Incidence

currently tested or

RSSI is imp

Driver. Dur

OpenTag b

normalized

antenna (ty

by calling r

One Example of Using RSSI for LocationUsing large numbers of low-cost, battery-powered fixed position nodes is cheap and

(location list)

(derived

of mobi

(packet data)

Can OpenTag [and DASH7]

do Multihop and Mesh?

DASH7 Mode 2 & OpenTag Support Limited MultihoppingDASH7‘s advanced query functionality and long range deprecate needs for complex

DASH7 Mode 2 Network Routing Template

Routable DASH7 Mode 2 frame, as seen by network protoco

DASH7 Mode 2 Network Routing Template

Routable DASH7 Mode 2 frame, as seen by network protoco

Routing Functions in OpenTag Network Module

• Function network_route_ff() is

automatically called by OpenTag when

parsing an incoming frame! returns 0 if the frame is routed to this device

! returns positive number (corresponding to

routing table index) if frame is routed to a

known device

! returns -1 if frame should be discarded

• Function m2np_header() writes a properlyrouted M2NP header to a new frame.

! routing algorithm needs to store the routing

information in the m2np data structure, so

m2np_header() can use it.

! m2np data structure is exposed, so you can

put routing algorithm anywhere you want.

Routing Functions in OpenTag Network Module

• Function network_route_ff() is

automatically called by OpenTag when

parsing an incoming frame! returns 0 if the frame is routed to this device

! returns positive number (corresponding to

routing table index) if frame is routed to a

known device

! returns -1 if frame should be discarded

•Function

m2np_header() writes a properly

routed M2NP header to a new frame.

! routing algorithm needs to store the routing

information in the m2np data structure, so

m2np_header() can use it.

! m2np data structure is exposed, so you can

put routing algorithm anywhere you want.

How are events processed?

(and, how good is the event

timing resolution)

What is an Event?

What is an Event?(For those among us who are not software nerds)

An event is anything that causes a program to stop doing what i

and start doing something else.

Some Examples

Events in OpenTag

• OpenTag includes an event and task manager that runs parallel to the user’s application

• When an event occurs, OpenTag takes control of the system in order to run the task assocevent. It gives back control when the Task is done (or when it’s idle)

What Actually Happens when an Event Occurs?

• Any event must call sys_event_manager() in the system module(system.c) in order to bind a task to the event that just occurred.

! System Timer Events are managed internally by OpenTag, so when the

system timer expires, the appropriate task is automatically processed.

! The system timer is always running. So events can be queued up

during OpenTag tasks (expired events are discarded).

How Fast is the Event Timing Resolution?

• The OpenTag system timer runs at a resolution

of “1 tick,” where 1 tick = 1/1024 sec

! Roughly 1 ms! Allows usage of 32768 Hz crystal as source

• There is another timer unit called a “short tick”

equal to 1/32768 sec (~30.5 µs)

! Not used at all in OpenTag library (OTlib)

! Used only for internal radio processes,

although certain radios have internal timersand don’t need to use an MCU timer at all.

! All DASH7 processes are timed in ticks. So

short ticks are only necessary if you are an

optimizer and want to establish internal timer

offsets that are shorter than 1 tick.

How many simultaneous

connections are supported?

This Answer Depends on What You Mean by “Connection”

• Answer: 1

! This is like cable-replacement, w

something DASH7 is designed t! Requires either complex time-slo

Bluetooth) or even more comple

(802.11n, CDMA, OFDM) in orde

multiple isochronous connection

Connection Model 1

(Isochronous, streaming data)

• Answer: 1

! This is like cable-replacement, w

something DASH7 is designed t! Requires either complex time-slo

Bluetooth) or even more comple

(802.11n, CDMA, OFDM) in orde

multiple isochronous connection

Connection Model 1

(Isochronous, streaming data)

• Answer: a lot (potentially 1000’s)

! This is broadcast-query-respond

is designed to do especially well! Basic queries of thousands of de

accomplished without much ove

! Follow-up dialogs with queried d

by available memory and idle-tim

Connection Model 2

(Bursty, queued data)

H i d t t d

How is data stored

and logged?

U i h O T Fil ( ll d V li )

Using the OpenTag Filesystem (called Veelite)

• In C, it is a lot like using the POSIX C library

! FILE* — vlFILE*

! fopen() — vl_open(), vl_new()

! fclose() — vl_close()

! fgetc(), fputc() — vl_read(), vl_write()

• You can also access files by DASH7 itself,

using an Application Subprotocol (included in

OpenTag), as long as you have appropriate

user access to the files you want.

• The Application Subprotocol for file access is

also used over a wire, for the Serial-API, if you

are connecting an OpenTag module to another

piece of HW.

Wh t i th d l ith i l

What is the deal with wireless

regulations at 433 MHz?

433 MHz is Usually Available License-free (or cheaply)

Plus: no regulations in Antarctica!

433 MH R l t P li S

433 MHz Regulatory Policy Summary

Regulation Complexity Usage Notes Simplified Specification

FCC Part 15.231 High General Use

Spectrum: 420 - 450 MHz (20 MHz)

Max EIRP: highly variable, but effectively -2.4 dBmMax Duty Cycle: highly variable, but effectively 50

Max TX time: highly variable, but effectively 100 m

Beacons: requires very low duty cycle, or alternat

FCC Part 15.240 Moderate For Containers only

Similar to 15.231 but with simpler rules, no allow

and longer TX time permitted. In most cases it d

improve performance of DASH7 Mode 2 over 15

ETSI ERC 70-03 Low General UseSpectrum: 433.05 - 434.79 MHz (1.74 MHz)Class 1: 0 dBm @ 100% duty cycle, max TX 36 s

Class 2: 10 dBm @ 10% duty cycle, max TX 36 s

Korean ETRI Low General UseSpectrum: 433.67 - 434.17 MHz (500 KHz)

Max EIRP: 0 dBm

Japanese RR Low Logistics only

Max TX time: 100 ms

(Note: for guidance only, I am not an expert on

See you next time…

How about

that one?

No way! I only

date guys who use

OpenTag

See you next time…

How about

that one?

No way! I only

date guys who use

OpenTag

opentag webinar3

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