Bluetooth project questions
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Posts: 46,084
Hello all-
I'm considering a small project using BASIC stamps and their
bluetooth transceivers, but I have a few questions that did not
appear to be covered from the documentation I could find on the
Parallax site.
Basically I want to use a PC as a base station, able to send short
text messages (25 chars max) to bluetooth enabled remote kits, which
will then display those messages on a 2x16 LCD panel. (All
components will be Parallax units.)
I've got a good idea of what components are necessary, and have a
handle on the programming that will be necessary. My setup is one
base station and possibly two to four 'receiver' units. They will be
about 50 to 100 feet apart.
Questions:
Am I able to connect to multiple bluetooth receivers, and send a
message to each of them simultaneously? If so, how many? Or must I
establish a connection with each receiver, send the message,
disconnect, and connect to the next unit?
My requirement for total time to broadcast a message to up to four
receivers is about 2 seconds. Is this possible? It is not a problem
if I have to establish and maintain multiple connections by sending
frequent SYN signals... in other words, initial connection time is
not a factor, only total message broadcast time to all receivers.
Thanks for your responses.
I'm considering a small project using BASIC stamps and their
bluetooth transceivers, but I have a few questions that did not
appear to be covered from the documentation I could find on the
Parallax site.
Basically I want to use a PC as a base station, able to send short
text messages (25 chars max) to bluetooth enabled remote kits, which
will then display those messages on a 2x16 LCD panel. (All
components will be Parallax units.)
I've got a good idea of what components are necessary, and have a
handle on the programming that will be necessary. My setup is one
base station and possibly two to four 'receiver' units. They will be
about 50 to 100 feet apart.
Questions:
Am I able to connect to multiple bluetooth receivers, and send a
message to each of them simultaneously? If so, how many? Or must I
establish a connection with each receiver, send the message,
disconnect, and connect to the next unit?
My requirement for total time to broadcast a message to up to four
receivers is about 2 seconds. Is this possible? It is not a problem
if I have to establish and maintain multiple connections by sending
frequent SYN signals... in other words, initial connection time is
not a factor, only total message broadcast time to all receivers.
Thanks for your responses.
Comments
protocol and as such, you can only connect to one bluetooth
device at a time per bluetooth adaptor on your PC. I don't
recall ever hearing a conversation about using more than one
transciever on a pc so I don't know if that is a way around
things or not.
If you open the comm port for the bluetooth device on the
PC, you can transmit to a bluetooth device without
connecting. You can test this by opening hyperterminal on
the bluetooth port and watching what happens. Just follow
the directions in the eb500 manual. It's pretty good.
connecting is only necessary if you want to run with several
devices that only hear when they are the target. This is to
handle the networking capability of bluetooth but not
strictly needed if each message has a tag that each
receiving device can decode and ignore other messages.
I would make the stamp wait until it sees a pattern like
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxdev1:
or
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxdev2:
make the stamp read 25 characters plus the device id
(dev1[noparse]:)[/noparse]. When the serin command completes, the data will be
in an array and all you have to do is process it and not
mess with filtering.
Most bluetooth devices are class II devices. That means they
have a maximum range of 30 feet. There are three classes od
device in the spec and they are 1,10, and 100 meters
respectivly. since the eb500 claims a range of well over 30
feet, it is obviously a class III (or I, i don't remember).
In any case, the bluetooth device you buy for your PC is
most likel going to be a class II device. I don't know if
anyone is making a class II device for a PC or not, stoppped
paying attention a year or so ago.
You could build a stamp based repeater to extend ranges if
necessary.
The eb500 looks like a serial device to the stamp. On the
PC, you open the com port that is associated with the
bluetooth device installed.
hope this helps.
---- Original message ----
>Date: Fri, 06 Feb 2004 00:59:29 -0000
>From: "Darryl Watson" <dwatson@n...>
>Subject: [noparse][[/noparse]basicstamps] Bluetooth project questions
>To: basicstamps@yahoogroups.com
>
>Hello all-
>
>I'm considering a small project using BASIC stamps and
their
>bluetooth transceivers, but I have a few questions that did
not
>appear to be covered from the documentation I could find on
the
>Parallax site.
>
>Basically I want to use a PC as a base station, able to
send short
>text messages (25 chars max) to bluetooth enabled remote
kits, which
>will then display those messages on a 2x16 LCD panel. (All
>components will be Parallax units.)
>
>I've got a good idea of what components are necessary, and
have a
>handle on the programming that will be necessary. My setup
is one
>base station and possibly two to four 'receiver' units.
They will be
>about 50 to 100 feet apart.
>
>Questions:
>
>Am I able to connect to multiple bluetooth receivers, and
send a
>message to each of them simultaneously? If so, how many?
Or must I
>establish a connection with each receiver, send the
message,
>disconnect, and connect to the next unit?
>
>My requirement for total time to broadcast a message to up
to four
>receivers is about 2 seconds. Is this possible? It is not
a problem
>if I have to establish and maintain multiple connections by
sending
>frequent SYN signals... in other words, initial connection
time is
>not a factor, only total message broadcast time to all
receivers.
>
>Thanks for your responses.
>
>
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in
the Subject and Body of the message will be ignored.
>
>Yahoo! Groups Links
>
>
>
>
>
--
Regards
Dave Evartt
w:202 708-4932 x3250
h:410 439-2319
> If you open the comm port for the bluetooth device on the
> PC, you can transmit to a bluetooth device without
> connecting. You can test this by opening hyperterminal on
> the bluetooth port and watching what happens. Just follow
> the directions in the eb500 manual. It's pretty good.
>
This is great news. I'm new to Bluetooth, so my browse of the
documentation left me with the impression you HAVE to connect to other
devices to communicate. If the base station can transmit formatted
messages and my receivers all get them simultaneously, then the issue
is resolved.
> Most bluetooth devices are class II devices. That means they
> have a maximum range of 30 feet. There are three classes od
> device in the spec and they are 1,10, and 100 meters
> respectivly. since the eb500 claims a range of well over 30
> feet, it is obviously a class III (or I, i don't remember).
> In any case, the bluetooth device you buy for your PC is
> most likel going to be a class II device. I don't know if
> anyone is making a class II device for a PC or not, stoppped
> paying attention a year or so ago.
I can simply attach another stamp with a serial interface to the PC,
and I've got the range needed. I can easily write a C# windows
application to talk to the stamp.
>
> You could build a stamp based repeater to extend ranges if
> necessary.
>
Great idea.
Dave, thanks for the info!
My hobby is videography, so I spend most of my time making indie
movies, commercials, and music videos. We often tape live shows with
multiple cameras, which requires a director to be able to give
realtime commands to the operators, such as 'Zoom in to bass player'
or 'Give me a two-shot of the lead singer and drummer.'
The problem with many live events is that the noise level is too high
for my camera people to hear direction over our headphones, so a
portable wireless device which can attach to a camera and display
simple commands would be very useful to us.
Great forum, thanks.
You project sounds quite interesting. The Bluetooth Transceiver
AppMod (eb500) will work well for you, and I have some specific
recommendations about how to proceed.
>> Basically I want to use a PC as a base station,
>> able to send short text messages (25 chars max)
>> to bluetooth enabled remote kits
This is a good topology and will be quite simple to setup. Since you
are using Basic Stamps and eb500 AppMods, the main choice that you
need to make is which Bluetooth solution to use on the PC. While the
eb500 has plenty of range to meet your requirement of 50 to 100
feet, many of the PC USB dongles do not. You will need to select one
that is rated at Class 1 to make sure that you get plenty of range.
The second important factor in selection of a PC USB dongle has to
do with the software that it ships with. On a PC a lot of the
Bluetooth stack actually runs on the PC itself and the quality of
this software will effect how well it works for you. Most PC devices
these days ship with software that is licensed from Widcomm. This
stack is quite good and is the basis for all of the PC examples in
the eb500 manual. If the software installs an icon on your desktop
called "My Bluetooth Places" then it is from Widcomm.
For your application I would recommend the LinkSys USBBT100
Bluetooth USB adapter. It ships with the Widcomm stack and will
easily get the range that you need when communicating with an eb500
module. You can pick one of these up from Amazon.com for less then
fifty dollars.
>> Am I able to connect to multiple bluetooth
>> receivers, and send a message to each of them
>> simultaneously? If so, how many? Or must I
>> establish a connection with each receiver,
>> send the message, disconnect, and connect to
>> the next unit?
From the PC you can connect with up to seven eb500 devices
simultaneously through a single Bluetooth USB adapter. The reason
for the limitation is a bit complex but put simply has to due with
the way in which Bluetooth radios stay connected to each other.
There are some potential ways to extend this, but in general you
will see this limitation across all Bluetooth devices.
Once setup, communications with each of your devices from the PC is
very simple. Each one will have a unique virtual COM port number on
the PC and can be accessed directly. When you open the COM port the
connection will be established and when you close it the connection
will be destroyed. You can "broadcast" a message simply by writing
it to the COM port associated with each eb500 device. If you want to
send a message to only one device, only write the message to that
one COM port.
>> My requirement for total time to broadcast
>> a message to up to four receivers is about
>> 2 seconds.
You should be able to get the message delivered to all four of your
recievers within 50ms. If you extend your topology to seven devices
from four you may notice the time increase a bit. Basically the more
devices that you are communicating with, the more work that the
radio on the PC side has to do.
I hope that this answers your questions.
Talk to you soon,
Bryan Hall
A7 Engineering
www.a7eng.com
Bluetooth USB adapter. It ships with the Widcomm stack and will
easily get the range that you need when communicating with an eb500
module. You can pick one of these up from Amazon.com for less then
fifty dollars."
On eBay right now:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3076354407
Graffiti. Civilized people mark their territory with razor wire.
Scott
From: "Bryan Hall" <bryan@f...>
Reply-To: basicstamps@yahoogroups.com
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Bluetooth project questions
Date: Sat, 07 Feb 2004 23:34:34 -0000
Hello Darryl,
You project sounds quite interesting. The Bluetooth Transceiver
AppMod (eb500) will work well for you, and I have some specific
recommendations about how to proceed.
>> Basically I want to use a PC as a base station,
>> able to send short text messages (25 chars max)
>> to bluetooth enabled remote kits
This is a good topology and will be quite simple to setup. Since you
are using Basic Stamps and eb500 AppMods, the main choice that you
need to make is which Bluetooth solution to use on the PC. While the
eb500 has plenty of range to meet your requirement of 50 to 100
feet, many of the PC USB dongles do not. You will need to select one
that is rated at Class 1 to make sure that you get plenty of range.
The second important factor in selection of a PC USB dongle has to
do with the software that it ships with. On a PC a lot of the
Bluetooth stack actually runs on the PC itself and the quality of
this software will effect how well it works for you. Most PC devices
these days ship with software that is licensed from Widcomm. This
stack is quite good and is the basis for all of the PC examples in
the eb500 manual. If the software installs an icon on your desktop
called "My Bluetooth Places" then it is from Widcomm.
For your application I would recommend the LinkSys USBBT100
Bluetooth USB adapter. It ships with the Widcomm stack and will
easily get the range that you need when communicating with an eb500
module. You can pick one of these up from Amazon.com for less then
fifty dollars.
>> Am I able to connect to multiple bluetooth
>> receivers, and send a message to each of them
>> simultaneously? If so, how many? Or must I
>> establish a connection with each receiver,
>> send the message, disconnect, and connect to
>> the next unit?
From the PC you can connect with up to seven eb500 devices
simultaneously through a single Bluetooth USB adapter. The reason
for the limitation is a bit complex but put simply has to due with
the way in which Bluetooth radios stay connected to each other.
There are some potential ways to extend this, but in general you
will see this limitation across all Bluetooth devices.
Once setup, communications with each of your devices from the PC is
very simple. Each one will have a unique virtual COM port number on
the PC and can be accessed directly. When you open the COM port the
connection will be established and when you close it the connection
will be destroyed. You can "broadcast" a message simply by writing
it to the COM port associated with each eb500 device. If you want to
send a message to only one device, only write the message to that
one COM port.
>> My requirement for total time to broadcast
>> a message to up to four receivers is about
>> 2 seconds.
You should be able to get the message delivered to all four of your
recievers within 50ms. If you extend your topology to seven devices
from four you may notice the time increase a bit. Basically the more
devices that you are communicating with, the more work that the
radio on the PC side has to do.
I hope that this answers your questions.
Talk to you soon,
Bryan Hall
A7 Engineering
www.a7eng.com
To UNSUBSCRIBE, just send mail to:
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