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Thread

RF communications

2006-03-10 by Bryan Martin

I am working with linx txd-433-kh RF module for remote communications.  I am 
using Atmel atmega8515 microcontroller w/a SDK500 board.  The problem I am 
having is that the when I take the data pins high on the tx module it is 
being passed a voltage of around 5.80v.  The tx module wants the voltage 
below 5 to function so I attempted to place a 180ohm resistor in series 
which didnt do anything to the voltage but if I parallel the resistor with 
ground I get acceptable voltage and the module works.  Thing is for 1 that 
means I will have to run resistors on all the TX data pins coming from the 
microcontroller.  This also creates heat on the resistors ( I guess this is 
acceptable ) and causes power loss which may be a factor running from 
batteries.

Is their another better way around this?  BTW dropping the voltage to the 
microcontroller from the battery is not currently an option.

Re: [AVR-Chat] RF communications

2006-03-10 by Kathy Quinlan

Bryan Martin wrote:

> I am working with linx txd-433-kh RF module for remote communications.  I am 
> using Atmel atmega8515 microcontroller w/a SDK500 board.  The problem I am 
> having is that the when I take the data pins high on the tx module it is 
> being passed a voltage of around 5.80v.  The tx module wants the voltage 
> below 5 to function so I attempted to place a 180ohm resistor in series 
> which didnt do anything to the voltage but if I parallel the resistor with 
> ground I get acceptable voltage and the module works.  Thing is for 1 that 
> means I will have to run resistors on all the TX data pins coming from the 
> microcontroller.  This also creates heat on the resistors ( I guess this is 
> acceptable ) and causes power loss which may be a factor running from 
> batteries.
> 
> Is their another better way around this?  BTW dropping the voltage to the 
> microcontroller from the battery is not currently an option. 

Use a better regulator. 5.8V is a bit to much for a 5V rail, if you are 
talking of the rail voltage on the STK500, then drop the voltage back to 5.0V 
(advanced tab in STK500 programming section, board voltage :)



-- 
Regards,

Kat.
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Re: [AVR-Chat] RF communications

2006-03-10 by Bryan Martin

Thanks for your response.  I will check into the dropping the from the STK 
but the pblm is not on the rails.  I am getting 4.9v as expected from the 5v 
rail.  Problem is when I take a pin high on the 8515 it is sending more than 
the 5v.  It is sending around 5.80v.


----- Original Message -----

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From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
To: <AVR-Chat@yahoogroups.com>
Sent: Thursday, March 09, 2006 9:48 PM
Subject: Re: [AVR-Chat] RF communications


> Bryan Martin wrote:
>
>> I am working with linx txd-433-kh RF module for remote communications.  I 
>> am
>> using Atmel atmega8515 microcontroller w/a SDK500 board.  The problem I 
>> am
>> having is that the when I take the data pins high on the tx module it is
>> being passed a voltage of around 5.80v.  The tx module wants the voltage
>> below 5 to function so I attempted to place a 180ohm resistor in series
>> which didnt do anything to the voltage but if I parallel the resistor 
>> with
>> ground I get acceptable voltage and the module works.  Thing is for 1 
>> that
>> means I will have to run resistors on all the TX data pins coming from 
>> the
>> microcontroller.  This also creates heat on the resistors ( I guess this 
>> is
>> acceptable ) and causes power loss which may be a factor running from
>> batteries.
>>
>> Is their another better way around this?  BTW dropping the voltage to the
>> microcontroller from the battery is not currently an option.
>
> Use a better regulator. 5.8V is a bit to much for a 5V rail, if you are
> talking of the rail voltage on the STK500, then drop the voltage back to 
> 5.0V
> (advanced tab in STK500 programming section, board voltage :)
>
>
>
> -- 
> Regards,
>
> Kat.
> ---------------------------------------------------------------
>  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
>  For Everything Electronics    Phone: 0419 923 731
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Re: [AVR-Chat] RF communications

2006-03-10 by David Kelly

On Mar 9, 2006, at 7:35 PM, Bryan Martin wrote:

> Is their another better way around this?  BTW dropping the voltage  
> to the
> microcontroller from the battery is not currently an option.

You mean to say you are running your AVR over 5.8 volts? If so, then  
you have worse troubles coming than you know.

--
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

Re: [AVR-Chat] RF communications

2006-03-10 by Kathy Quinlan

Bryan Martin wrote:

> Thanks for your response.  I will check into the dropping the from the STK 
> but the pblm is not on the rails.  I am getting 4.9v as expected from the 5v 
> rail.  Problem is when I take a pin high on the 8515 it is sending more than 
> the 5v.  It is sending around 5.80v.

IF THE +5V rail is 5V then the pins CAN NOT PUT OUT MORE THAN 5V !!!!!!!

Are you feeding the same 5V to the RF Module ??


-- 
Regards,

Kat.
---------------------------------------------------------------
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  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
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Re: [AVR-Chat] RF communications

2006-03-10 by Bryan Martin

Well thats a yes and no.  I currently have a 12v wall wart going into a 
NX1000 dev board.  From there I take 12v off the nx1000 and go to the stk500 
dev board.  I also take 5V off the nx1000 and go to the VCC and ground plane 
of the breadboard that holds the RF modules.  I think I will try to clean 
this up first in hopes that is the pblm.  I will try to drop the NX1000 dev 
board all the way out of the picture first and hook the wall wart direct to 
the SDK500 even though that will still be pushing 5.8v when taking the pins 
high.  That would be controlled by the STK500 I think.

Bryan

----- Original Message -----

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From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
To: <AVR-Chat@yahoogroups.com>
Sent: Friday, March 10, 2006 9:07 AM
Subject: Re: [AVR-Chat] RF communications


> Bryan Martin wrote:
>
>> Thanks for your response.  I will check into the dropping the from the 
>> STK
>> but the pblm is not on the rails.  I am getting 4.9v as expected from the 
>> 5v
>> rail.  Problem is when I take a pin high on the 8515 it is sending more 
>> than
>> the 5v.  It is sending around 5.80v.
>
> IF THE +5V rail is 5V then the pins CAN NOT PUT OUT MORE THAN 5V !!!!!!!
>
> Are you feeding the same 5V to the RF Module ??
>
>
> -- 
> Regards,
>
> Kat.
> ---------------------------------------------------------------
>  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
>  For Everything Electronics    Phone: 0419 923 731
> ---------------------------------------------------------------
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> No virus found in this outgoing message.
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Re: [AVR-Chat] RF communications

2006-03-10 by Zack Widup

On Fri, 10 Mar 2006, Bryan Martin wrote:

> Thanks for your response.  I will check into the dropping the from the STK
> but the pblm is not on the rails.  I am getting 4.9v as expected from the 5v
> rail.  Problem is when I take a pin high on the 8515 it is sending more than
> the 5v.  It is sending around 5.80v.
> 

Are you using external pullup resistors?  I'd suggest using a voltage 
regulator to put 5.0 volts on the pullup line.

Zack

Re: [AVR-Chat] RF communications

2006-03-10 by Kathy Quinlan

Bryan Martin wrote:

> Well thats a yes and no.  I currently have a 12v wall wart going into a 
> NX1000 dev board.  From there I take 12v off the nx1000 and go to the stk500 
> dev board.  I also take 5V off the nx1000 and go to the VCC and ground plane 
> of the breadboard that holds the RF modules.  I think I will try to clean 
> this up first in hopes that is the pblm.  I will try to drop the NX1000 dev 
> board all the way out of the picture first and hook the wall wart direct to 
> the SDK500 even though that will still be pushing 5.8v when taking the pins 
> high.  That would be controlled by the STK500 I think.
> 
> Bryan
> 

FIRST off, do you have a good connection STRAIGHT from the STK500 0V to the RF 
modules 0V as if you do not, or it is routed through other boards, this could 
induce the voltage rise you are seeing and cause a lot of problems (DC is only 
one, the AC ie noise etc. IS A LOT MORE)

If you do not have a good 0V connection between the two, try it, it will 
probably solve a few problems.

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


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Re: [AVR-Chat] RF communications

2006-03-10 by Bryan Martin

That may be it.  I am sourcing the VCC and ground from the NX1000 board and 
not the SDK500 that holds the MCU.  I plan to check this tonight.  Thanks 
for the heads up.


----- Original Message -----

Show quoted textHide quoted text

From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
To: <AVR-Chat@yahoogroups.com>
Sent: Friday, March 10, 2006 9:56 AM
Subject: Re: [AVR-Chat] RF communications


> Bryan Martin wrote:
>
>> Well thats a yes and no.  I currently have a 12v wall wart going into a
>> NX1000 dev board.  From there I take 12v off the nx1000 and go to the 
>> stk500
>> dev board.  I also take 5V off the nx1000 and go to the VCC and ground 
>> plane
>> of the breadboard that holds the RF modules.  I think I will try to clean
>> this up first in hopes that is the pblm.  I will try to drop the NX1000 
>> dev
>> board all the way out of the picture first and hook the wall wart direct 
>> to
>> the SDK500 even though that will still be pushing 5.8v when taking the 
>> pins
>> high.  That would be controlled by the STK500 I think.
>>
>> Bryan
>>
>
> FIRST off, do you have a good connection STRAIGHT from the STK500 0V to 
> the RF
> modules 0V as if you do not, or it is routed through other boards, this 
> could
> induce the voltage rise you are seeing and cause a lot of problems (DC is 
> only
> one, the AC ie noise etc. IS A LOT MORE)
>
> If you do not have a good 0V connection between the two, try it, it will
> probably solve a few problems.
>
> -- 
> Regards,
>
> Kat.
> ---------------------------------------------------------------
>  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
>  For Everything Electronics    Phone: 0419 923 731
> ---------------------------------------------------------------
>
>
> -- 
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.375 / Virus Database: 268.2.1/278 - Release Date: 9/03/2006
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>
>
> Yahoo! Groups Links
>
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Re: [AVR-Chat] RF communications

2006-03-10 by Jim Wagner

I'd bet that something on the board driven by the micro is
trying to pull higher than 5V. Like a pullup resistor
connected to +12. When the micro output is high, it cannot
handle current in that "wrong" direction. It expects
current flow to ground. If its going the other way, it will
fail to operate properly.'

Jim

On Fri, 10 Mar 2006 22:07:00 +0800
 Kathy Quinlan <kat-yahoo@kaqelectronics.dyndns.org> wrote:
> Bryan Martin wrote:
> 
> > Thanks for your response.  I will check into the
> dropping the from the STK 
> > but the pblm is not on the rails.  I am getting 4.9v as
> expected from the 5v 
> > rail.  Problem is when I take a pin high on the 8515 it
> is sending more than 
> > the 5v.  It is sending around 5.80v.
> 
> IF THE +5V rail is 5V then the pins CAN NOT PUT OUT MORE
> THAN 5V !!!!!!!
> 
> Are you feeding the same 5V to the RF Module ??
> 
> 
> -- 
> Regards,
> 
> Kat.
>
---------------------------------------------------------------
>   K.A.Q. Electronics     Website:
> www.kaqelectronics.dyndns.org
>   IM: Yahoo: PinkyDwaggy MSN:
> katinka@kaqelectronics.dyndns.org
>   For Everything Electronics 		   Phone: 0419 923 731
>
---------------------------------------------------------------
> 
> 
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> No virus found in this outgoing message.
> Checked by AVG Free Edition.
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> Date: 9/03/2006
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> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 

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Re: [AVR-Chat] RF communications

2006-03-10 by David Kelly

On Fri, Mar 10, 2006 at 11:43:14AM -0500, Jim Wagner wrote:
> I'd bet that something on the board driven by the micro is
> trying to pull higher than 5V. Like a pullup resistor
> connected to +12. When the micro output is high, it cannot
> handle current in that "wrong" direction. It expects
> current flow to ground. If its going the other way, it will
> fail to operate properly.'

There is a pullup protection diode on the AVR ports. 5.8 is about what
one would see if its being over-voltaged from an external source. In
this case, the RF board.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

Re: [AVR-Chat] RF communications

2006-03-10 by Bryan Martin

Thanks guys.  I will check on this tonight and post back if I still cant 
find anything.

Thanks again,

Bryan

----- Original Message -----

Show quoted textHide quoted text

From: "David Kelly" <dkelly@hiwaay.net>
To: <AVR-Chat@yahoogroups.com>
Sent: Friday, March 10, 2006 12:57 PM
Subject: Re: [AVR-Chat] RF communications


> On Fri, Mar 10, 2006 at 11:43:14AM -0500, Jim Wagner wrote:
>> I'd bet that something on the board driven by the micro is
>> trying to pull higher than 5V. Like a pullup resistor
>> connected to +12. When the micro output is high, it cannot
>> handle current in that "wrong" direction. It expects
>> current flow to ground. If its going the other way, it will
>> fail to operate properly.'
>
> There is a pullup protection diode on the AVR ports. 5.8 is about what
> one would see if its being over-voltaged from an external source. In
> this case, the RF board.
>
> -- 
> David Kelly N4HHE, dkelly@HiWAAY.net
> ========================================================================
> Whom computers would destroy, they must first drive mad.
>
>
>
> Yahoo! Groups Links
>
>
>
>
>

Re: [AVR-Chat] RF communications

2006-03-11 by Bryan Martin

That was it.  When I sourced VCC and ground off the SDK500 the voltage went 
to 4.95 w/no resistors.  Question though while were are talking about this. 
Lets say I wanted to run two different power supplies one for part of the 
controller portion and another for the RF portion (picture 2 different 
battery banks - trying to isolate noise getting into the RF side) is this 
possible?  Would this work if I connected the ground planes together?


----- Original Message -----

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From: "Bryan Martin" <registration@myplaceinspace.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Friday, March 10, 2006 10:01 AM
Subject: Re: [AVR-Chat] RF communications


> That may be it.  I am sourcing the VCC and ground from the NX1000 board 
> and
> not the SDK500 that holds the MCU.  I plan to check this tonight.  Thanks
> for the heads up.
>
>
> ----- Original Message ----- 
> From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
> To: <AVR-Chat@yahoogroups.com>
> Sent: Friday, March 10, 2006 9:56 AM
> Subject: Re: [AVR-Chat] RF communications
>
>
>> Bryan Martin wrote:
>>
>>> Well thats a yes and no.  I currently have a 12v wall wart going into a
>>> NX1000 dev board.  From there I take 12v off the nx1000 and go to the
>>> stk500
>>> dev board.  I also take 5V off the nx1000 and go to the VCC and ground
>>> plane
>>> of the breadboard that holds the RF modules.  I think I will try to 
>>> clean
>>> this up first in hopes that is the pblm.  I will try to drop the NX1000
>>> dev
>>> board all the way out of the picture first and hook the wall wart direct
>>> to
>>> the SDK500 even though that will still be pushing 5.8v when taking the
>>> pins
>>> high.  That would be controlled by the STK500 I think.
>>>
>>> Bryan
>>>
>>
>> FIRST off, do you have a good connection STRAIGHT from the STK500 0V to
>> the RF
>> modules 0V as if you do not, or it is routed through other boards, this
>> could
>> induce the voltage rise you are seeing and cause a lot of problems (DC is
>> only
>> one, the AC ie noise etc. IS A LOT MORE)
>>
>> If you do not have a good 0V connection between the two, try it, it will
>> probably solve a few problems.
>>
>> -- 
>> Regards,
>>
>> Kat.
>> ---------------------------------------------------------------
>>  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
>>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
>>  For Everything Electronics    Phone: 0419 923 731
>> ---------------------------------------------------------------
>>
>>
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>> No virus found in this outgoing message.
>> Checked by AVG Free Edition.
>> Version: 7.1.375 / Virus Database: 268.2.1/278 - Release Date: 9/03/2006
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

Re: [AVR-Chat] RF communications

2006-03-11 by Kathy Quinlan

Bryan Martin wrote:

> That was it.  When I sourced VCC and ground off the SDK500 the voltage went 
> to 4.95 w/no resistors.  Question though while were are talking about this. 
> Lets say I wanted to run two different power supplies one for part of the 
> controller portion and another for the RF portion (picture 2 different 
> battery banks - trying to isolate noise getting into the RF side) is this 
> possible?  Would this work if I connected the ground planes together?

OK do you know much about electronics ?

If yes then you realise you need a common reference point or your signals will 
appear to float and you will get various problems.

If no, then here is the explanation:

If you have 2 batteries say 1.5V and 9V, if you measure from the positive of 
the 1.5V to the negative of the 1.5V you well get a voltage of 1.5V. The same 
with the 9V battery, measure from the + and - terminals and you will get 9V.

Now if you measure from the 1.5V's - terminal to the 9V + terminal, you will 
see no voltage (in the real world the multimeter will show some stray voltage, 
but this would only be a few milli volts) you will not measure 9V. The reason 
is the current has no where to go to return to the - terminal of the 9V battery.

So if we place a wire between the -terminal of the 1.5V and 9V batteries, and 
then measure between this wire and the + of either battery, we will see 1.5V 
at the + terminal of the 1.5V battery and 9V at the + terminal of the 9V battery.

So why did you measure 5.8V in your RF module:

Well there are 2 main reasons:

#1 the module was being feed from more than +5V

#2 the length of wire between the 0V rails on the different boards (possibly 
through resistors, diodes etc) was sufficient to raise the 0V rail of the RF 
module to 0.8V

I hope this helps.

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
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Re: [AVR-Chat] RF communications

2006-03-11 by Bryan Martin

Thanks for the explination Kat.  I am learning as I go so please excuse the 
newbee question but I learned something new.

Thanks again,

Bryan

----- Original Message -----

Show quoted textHide quoted text

From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
To: <AVR-Chat@yahoogroups.com>
Sent: Friday, March 10, 2006 8:37 PM
Subject: Re: [AVR-Chat] RF communications


> Bryan Martin wrote:
>
>> That was it.  When I sourced VCC and ground off the SDK500 the voltage 
>> went
>> to 4.95 w/no resistors.  Question though while were are talking about 
>> this.
>> Lets say I wanted to run two different power supplies one for part of the
>> controller portion and another for the RF portion (picture 2 different
>> battery banks - trying to isolate noise getting into the RF side) is this
>> possible?  Would this work if I connected the ground planes together?
>
> OK do you know much about electronics ?
>
> If yes then you realise you need a common reference point or your signals 
> will
> appear to float and you will get various problems.
>
> If no, then here is the explanation:
>
> If you have 2 batteries say 1.5V and 9V, if you measure from the positive 
> of
> the 1.5V to the negative of the 1.5V you well get a voltage of 1.5V. The 
> same
> with the 9V battery, measure from the + and - terminals and you will get 
> 9V.
>
> Now if you measure from the 1.5V's - terminal to the 9V + terminal, you 
> will
> see no voltage (in the real world the multimeter will show some stray 
> voltage,
> but this would only be a few milli volts) you will not measure 9V. The 
> reason
> is the current has no where to go to return to the - terminal of the 9V 
> battery.
>
> So if we place a wire between the -terminal of the 1.5V and 9V batteries, 
> and
> then measure between this wire and the + of either battery, we will see 
> 1.5V
> at the + terminal of the 1.5V battery and 9V at the + terminal of the 9V 
> battery.
>
> So why did you measure 5.8V in your RF module:
>
> Well there are 2 main reasons:
>
> #1 the module was being feed from more than +5V
>
> #2 the length of wire between the 0V rails on the different boards 
> (possibly
> through resistors, diodes etc) was sufficient to raise the 0V rail of the 
> RF
> module to 0.8V
>
> I hope this helps.
>
> -- 
> Regards,
>
> Kat.
> ---------------------------------------------------------------
>  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
>  For Everything Electronics    Phone: 0419 923 731
> ---------------------------------------------------------------
>
>
> -- 
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.375 / Virus Database: 268.2.1/279 - Release Date: 10/03/2006
>
>
>
> Yahoo! Groups Links
>
>
>
>
>

Re: [AVR-Chat] RF communications

2006-03-11 by John Samperi

At 12:37 PM 11/03/2006, you wrote:
>So why did you measure 5.8V in your RF module:
>
>Well there are 2 main reasons:

A 3rd perhaps? RF was stuffing up the readings? I had
some problems when working with a GSM modem and the RS232
signal were being messed up by the RF. A few 100nF caps
at the appropriate points solved the "issues" as they say
nowadays.

Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

Re: [AVR-Chat] RF communications

2006-03-11 by Kathy Quinlan

Bryan Martin wrote:

> Thanks for the explination Kat.  I am learning as I go so please excuse the 
> newbee question but I learned something new.
> 
> Thanks again,
> 
> Bryan
> 

We were all newbies once, glad to be able to help.

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


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Re: [AVR-Chat] RF communications

2006-03-12 by Ned Konz

On Mar 10, 2006, at 6:14 AM, Bryan Martin wrote:

> Well thats a yes and no.  I currently have a 12v wall wart going  
> into a
> NX1000 dev board.  From there I take 12v off the nx1000 and go to  
> the stk500
> dev board.  I also take 5V off the nx1000 and go to the VCC and  
> ground plane
> of the breadboard that holds the RF modules.

You have to look at the power supply input circuitry of both boards.  
I believe both have diode bridges between their power supply inputs  
and their regulators.

So the NX1000 "ground" signal becomes +0.6 or so volts on the STK500  
(because of 1 diode drop).

Which means that the +5V on the STK500 is at +5.6 or so with respect  
to the ground on the NX1000 (and your breadboard). Hence the funny  
readings.

You'd be better off, all things considered, to run the wall wart into  
a "Y" cable and then into both the NX1000 and the STK500. Then  
(assuming that their ground voltages are about the same) you can  
connect their ground planes together.

Of course, if the forward voltage drops on the input diodes are  
different (say if one uses regular 1N4001 diodes and the other uses  
Schottky diodes) you'll have all the power supply current going  
through one pair of diodes (the Schottky diodes, which have lower  
forward voltage drops).

Try to look at the power supply circuitry for both the NX1000 and the  
STK500 boards; I think you'll see that both have diode bridges.

I know the STK500 does; from the picture it looks like the NX1000  
does too.

Show quoted textHide quoted text

> I think I will try to clean
> this up first in hopes that is the pblm.  I will try to drop the  
> NX1000 dev
> board all the way out of the picture first and hook the wall wart  
> direct to
> the SDK500 even though that will still be pushing 5.8v when taking  
> the pins
> high.  That would be controlled by the STK500 I think.
>
> Bryan
>
> ----- Original Message -----
> From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
> To: <AVR-Chat@yahoogroups.com>
> Sent: Friday, March 10, 2006 9:07 AM
> Subject: Re: [AVR-Chat] RF communications
>
>
>> Bryan Martin wrote:
>>
>>> Thanks for your response.  I will check into the dropping the  
>>> from the
>>> STK
>>> but the pblm is not on the rails.  I am getting 4.9v as expected  
>>> from the
>>> 5v
>>> rail.  Problem is when I take a pin high on the 8515 it is  
>>> sending more
>>> than
>>> the 5v.  It is sending around 5.80v.
>>
>> IF THE +5V rail is 5V then the pins CAN NOT PUT OUT MORE THAN  
>> 5V !!!!!!!
>>
>> Are you feeding the same 5V to the RF Module ??
>>
>>
>> -- 
>> Regards,
>>
>> Kat.
>> ---------------------------------------------------------------
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>>  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
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RF data communications headache

2006-03-12 by Thomas Keller

Greets.

   I have a headache.  I have a body-wearable electronics package, 
battery operated, which is generation on the order of 5 mbits/second of 
data which needs to be RF linked to a PC within 100-200 feet.  While 
there is no real reason the link itself needs to be an 802.11 link, 
utlimately, the data stream reaching the computer needs to be in TCP/IP 
UDP packets.  (I can handle generating the UDP packets at the recevier 
end of the RF link, if need be).

  My problem is getting the data from the body-wearable package TO a 
receiver. I have been looking at various solutions.  My personal 
favorite would have been Zigbee (IEEE 802.15.4) but the data bandwidth 
is simp;ly not there.  So, not finding anything else with sufficient 
bandwisfth and range, I find myself pretty much forced to lpook at 802.11.

   PROBLEM: how do I talk to an 802.11a/b/g WLAN adapter from an AVR?   
Should I choose a USB enabled AVR, and use a USB WLAN NIC?  Or should I 
try to use a PCMCIA or CF card WLAN adapter?   From what little I've 
been ab;e to find out, getting the necessary technival information to 
successfully communicate with and control PCMCIA and CF card adapters is 
difficult, at best.  (I also worry about the physivcal/electrical 
aspects of the interface).  I have plenty of bandwidth avai;labe in the 
AVR which will be cointrolling the RF card...only about 5% of 
itsresources are tied up in collecting the data stream from 4 uCs, each 
doing ADC on 32 channels of sensor data (2000 12 bit 
samples/sensor/second, total).  Going to implement a 16 bit data bus 
betwixt all the processors on the PCB (cheating, I know, but serial 
links just didn't look fesasible).

   So, what say ye, freinds and mentors?  Any suggestions, pointers to 
documents from which I can learn needed information/skills, criticisms, 
condemnations, proposals for committment, etc., etc?

tom
(aka avrFreak on eFnet IRC network)

Re: [AVR-Chat] RF data communications headache

2006-03-12 by Dave Hylands

Hi Thomas,

>    So, what say ye, freinds and mentors?  Any suggestions, pointers to
> documents from which I can learn needed information/skills, criticisms,
> condemnations, proposals for committment, etc., etc?

Check the AirDrop-A or AirDrop-P
http://www.edtp.com/

The book on implementing 802.11 with Microcontrollers includes a
detailed description of how everything works.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

Re: [AVR-Chat] RF data communications headache

2006-03-12 by Ned Konz

On Mar 12, 2006, at 7:03 AM, Thomas Keller wrote:

> Greets.
>
>    I have a headache.  I have a body-wearable electronics package,
> battery operated, which is generation on the order of 5 mbits/ 
> second of
> data which needs to be RF linked to a PC within 100-200 feet.  While
> there is no real reason the link itself needs to be an 802.11 link,
> utlimately, the data stream reaching the computer needs to be in  
> TCP/IP
> UDP packets.  (I can handle generating the UDP packets at the recevier
> end of the RF link, if need be).
>
>   My problem is getting the data from the body-wearable package TO a
> receiver. I have been looking at various solutions.  My personal
> favorite would have been Zigbee (IEEE 802.15.4) but the data bandwidth
> is simp;ly not there.  So, not finding anything else with sufficient
> bandwisfth and range, I find myself pretty much forced to lpook at  
> 802.11.
>
>    PROBLEM: how do I talk to an 802.11a/b/g WLAN adapter from an AVR?
> Should I choose a USB enabled AVR, and use a USB WLAN NIC?  Or  
> should I
> try to use a PCMCIA or CF card WLAN adapter?   From what little I've
> been ab;e to find out, getting the necessary technival information to
> successfully communicate with and control PCMCIA and CF card  
> adapters is
> difficult, at best.  (I also worry about the physivcal/electrical
> aspects of the interface).  I have plenty of bandwidth avai;labe in  
> the
> AVR which will be cointrolling the RF card...only about 5% of
> itsresources are tied up in collecting the data stream from 4 uCs,  
> each
> doing ADC on 32 channels of sensor data (2000 12 bit
> samples/sensor/second, total).  Going to implement a 16 bit data bus
> betwixt all the processors on the PCB (cheating, I know, but serial
> links just didn't look fesasible).
>
>    So, what say ye, freinds and mentors?  Any suggestions, pointers to
> documents from which I can learn needed information/skills,  
> criticisms,
> condemnations, proposals for committment, etc., etc?
>

Rather than doing it yourself, why not just pick up one of the Digi  
International all-in-one serial-to-(wireless)tcp server-in-a- 
connectors? They look pretty simple.

The Digi DC-WME-01T-S, for instance, is $130 (qty.1) and is entirely  
self-contained:
http://www.mouser.com/catalog/625/102.pdf

Show quoted textHide quoted text

> tom
> (aka avrFreak on eFnet IRC network)
>
>
>
>
> Yahoo! Groups Links
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RE: [AVR-Chat] RF data communications headache

2006-03-12 by stevech

What in the world would drive the need for 5Mbps sustained from an AVR (what
port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer is
6Mbps; 11g can be faster.

The huge problem with 802.11 is that these radios are power hogs. The PDAs
use 802.11 in the power saving mode, where the radio powers off in between
the 100mSec beacons, and the access point, if it's designed per the
standard, dequeues traffic for the power-saving client each beacon-time.

Re: [AVR-Chat] RF data communications headache

2006-03-13 by Daniel Adolfsson

Thomas Keller skrev:

>Greets.
>
>   I have a headache.  I have a body-wearable electronics package, 
>battery operated, which is generation on the order of 5 mbits/second of 
>data which needs to be RF linked to a PC within 100-200 feet.  While 
>there is no real reason the link itself needs to be an 802.11 link, 
>utlimately, the data stream reaching the computer needs to be in TCP/IP 
>UDP packets.  (I can handle generating the UDP packets at the recevier 
>end of the RF link, if need be).
>
>  My problem is getting the data from the body-wearable package TO a 
>receiver. I have been looking at various solutions.  My personal 
>favorite would have been Zigbee (IEEE 802.15.4) but the data bandwidth 
>is simp;ly not there.  So, not finding anything else with sufficient 
>bandwisfth and range, I find myself pretty much forced to lpook at 802.11.
>  
>
I have no idea how hard it would be to use, but I got to think about the 
external 802.11b network card I bought for my pda, its a SD-card 
("sdio") wich is about 5 mm longer than a normal storage card. And since 
sd uses some kind of i2c bus? it might be simpler to interface than for 
example a pcmcia card.
I bought mine of ebay, heres one just like it 
http://cgi.ebay.com/WLAN-Wi-Fi-802-11b-WiFi-Wireless-SDIO-SD-adapter-card-E_W0QQitemZ5879039791QQcategoryZ45003QQrdZ1QQcmdZViewItem

Just a thougth.

//Daniel Adolfsson

Re: [AVR-Chat] RF data communications headache

2006-03-14 by Thomas Keller

stevech wrote:
> What in the world would drive the need for 5Mbps sustained from an AVR (what
> port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer is
> 6Mbps; 11g can be faster.
>
>   

   Well, I am not at liberty to disclose the details.  Suffice (I hope) 
to say that thr wearable electronics will be instrumenting the body 
movements of a "dancer," whose digitzed movement data will be used to 
control other aspects f the stage environment for a performance art piece.

tom

Re: [AVR-Chat] RF data communications headache

2006-03-14 by Russell Shaw

Thomas Keller wrote:
> stevech wrote:
> 
>>What in the world would drive the need for 5Mbps sustained from an AVR (what
>>port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer is
>>6Mbps; 11g can be faster.
> 
>    Well, I am not at liberty to disclose the details.  Suffice (I hope) 
> to say that thr wearable electronics will be instrumenting the body 
> movements of a "dancer," whose digitzed movement data will be used to 
> control other aspects f the stage environment for a performance art piece.

When you consider that useable audio can be encoded at 8kbytes/sec, 5Mbits/sec
seems a bit over done just to measure 50 channels of movement.

Re: [AVR-Chat] RF data communications headache

2006-03-14 by Thomas Keller

Russell Shaw wrote:
> Thomas Keller wrote:
>   
>> stevech wrote:
>>
>>     
>>> What in the world would drive the need for 5Mbps sustained from an AVR (what
>>> port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer is
>>> 6Mbps; 11g can be faster.
>>>       
>>    Well, I am not at liberty to disclose the details.  Suffice (I hope) 
>> to say that thr wearable electronics will be instrumenting the body 
>> movements of a "dancer," whose digitzed movement data will be used to 
>> control other aspects f the stage environment for a performance art piece.
>>     
>
> When you consider that useable audio can be encoded at 8kbytes/sec, 5Mbits/sec
> seems a bit over done just to measure 50 channels of movement.
>   
   1287 channels of sensor data at 12 bits/channel, times 2000 
samples/channel/sec.

tom

RE: [AVR-Chat] RF data communications headache

2006-03-14 by stevech

1287 analog signals and that many A/D channels that can run in complete
parallelism?

Maybe then, you need a lower sample rate or use delta coding.

Sounds like a pipe dream to me.

Show quoted textHide quoted text

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Thomas Keller
Sent: Monday, March 13, 2006 5:41 PM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] RF data communications headache

Russell Shaw wrote:
> Thomas Keller wrote:
>   
>> stevech wrote:
>>
>>     
>>> What in the world would drive the need for 5Mbps sustained from an AVR
(what
>>> port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer
is
>>> 6Mbps; 11g can be faster.
>>>       
>>    Well, I am not at liberty to disclose the details.  Suffice (I hope) 
>> to say that thr wearable electronics will be instrumenting the body 
>> movements of a "dancer," whose digitzed movement data will be used to 
>> control other aspects f the stage environment for a performance art
piece.
>>     
>
> When you consider that useable audio can be encoded at 8kbytes/sec,
5Mbits/sec
> seems a bit over done just to measure 50 channels of movement.
>   
   1287 channels of sensor data at 12 bits/channel, times 2000 
samples/channel/sec.

tom


 
Yahoo! Groups Links

Re: [AVR-Chat] RF data communications headache

2006-03-14 by Russell Shaw

Thomas Keller wrote:
> Russell Shaw wrote:
> 
>>Thomas Keller wrote:
>>
>>>stevech wrote:
>>>
>>>>What in the world would drive the need for 5Mbps sustained from an AVR (what
>>>>port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer is
>>>>6Mbps; 11g can be faster.
>>>>      
>>>   Well, I am not at liberty to disclose the details.  Suffice (I hope) 
>>>to say that thr wearable electronics will be instrumenting the body 
>>>movements of a "dancer," whose digitzed movement data will be used to 
>>>control other aspects f the stage environment for a performance art piece.
>>>    
>>When you consider that useable audio can be encoded at 8kbytes/sec, 5Mbits/sec
>>seems a bit over done just to measure 50 channels of movement.
>>  
>    1287 channels of sensor data at 12 bits/channel, times 2000 
> samples/channel/sec.

Ok. 2k/sec is still quite high. If you transmit the differences (delta modulation),
a lot of compression would happen. A/u-law companding could be done too.

RE: [AVR-Chat] RF data communications headache

2006-03-14 by Mark Jordan

And what will be the size and weight of such circuit?

Show quoted textHide quoted text

On 13 Mar 2006 at 19:10, stevech wrote:

> 1287 analog signals and that many A/D channels that can run in complete
> parallelism?
> 
> Maybe then, you need a lower sample rate or use delta coding.
> 
> Sounds like a pipe dream to me.
> 
> -----Original Message-----
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
> Of Thomas Keller
> Sent: Monday, March 13, 2006 5:41 PM
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] RF data communications headache
> 
> Russell Shaw wrote:
> > Thomas Keller wrote:
> >   
> >> stevech wrote:
> >>
> >>     
> >>> What in the world would drive the need for 5Mbps sustained from an AVR
> (what
> >>> port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer
> is
> >>> 6Mbps; 11g can be faster.
> >>>       
> >>    Well, I am not at liberty to disclose the details.  Suffice (I hope) 
> >> to say that thr wearable electronics will be instrumenting the body 
> >> movements of a "dancer," whose digitzed movement data will be used to 
> >> control other aspects f the stage environment for a performance art
> piece.
> >>     
> >
> > When you consider that useable audio can be encoded at 8kbytes/sec,
> 5Mbits/sec
> > seems a bit over done just to measure 50 channels of movement.
> >   
>    1287 channels of sensor data at 12 bits/channel, times 2000 
> samples/channel/sec.
> 
> tom
> 
> 
>  
> Yahoo! Groups Links
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> 
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> Yahoo! Groups Links
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Re: [AVR-Chat] RF data communications headache

2006-03-14 by Thomas Keller

stevech wrote:
> 1287 analog signals and that many A/D channels that can run in complete
> parallelism?
>
> Maybe then, you need a lower sample rate or use delta coding.
>
> Sounds like a pipe dream to me.
>
> -----Original Message-----
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
> Of Thomas Keller
> Sent: Monday, March 13, 2006 5:41 PM
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] RF data communications headache
>
> Russell Shaw wrote:
>   
>> Thomas Keller wrote:
>>   
>>     
>>> stevech wrote:
>>>
>>>     
>>>       
>>>> What in the world would drive the need for 5Mbps sustained from an AVR
>>>>         
> (what
>   
>>>> port at 5Mbps anyway) via 802.11? As you may know, '11b at the TCP layer
>>>>         
> is
>   
>>>> 6Mbps; 11g can be faster.
>>>>       
>>>>         
>>>    Well, I am not at liberty to disclose the details.  Suffice (I hope) 
>>> to say that thr wearable electronics will be instrumenting the body 
>>> movements of a "dancer," whose digitzed movement data will be used to 
>>> control other aspects f the stage environment for a performance art
>>>       
> piece.
>   
>>>     
>>>       
>> When you consider that useable audio can be encoded at 8kbytes/sec,
>>     
> 5Mbits/sec
>   
>> seems a bit over done just to measure 50 channels of movement.
>>   
>>     
>    1287 channels of sensor data at 12 bits/channel, times 2000 
> samples/channel/sec.
>
> tom
>   
   Oops...pardon my sloppy typing.  128 channels, not 1287  *blush*

tom