AVR-Chat

On Tue, Jul 28, 2009 at 07:56:33AM -0700, hossein hashemi wrote:
> your last paragraph made i read the data sheet again.
> if data less than 32 bytes exp 25 bytes ,do you think it's transmitted after 30 ms?(pdf is not clear.)
> it's pleasant for me.
> 25 bytes as a 5 samples of one patient.but this 30ms,for monitoring, give a discrete state to data,isn't it? but i think i can use the static data for 30ms on monitor.
> my baud rate is 4800bps.but the data sheet hasn't determined? which baud rate has this problem.? 
> 
> 
> 
> 
> --- On Tue, 7/28/09, David Kelly <dkelly@hiwaay.net> wrote:
> 
> From: David Kelly <dkelly@hiwaay.net>
> Subject: Re: [AVR-Chat] RF module
> To: AVR-Chat@yahoogroups.com
> Date: Tuesday, July 28, 2009, 6:21 PM
> 
> 
> 
> 
> 
> 
> ?
> 
> 
> 
> 
>     
>                   On Tue, Jul 28, 2009 at 01:13:45PM -0000, iijfet wrote:
> 
> > hi,i wanna to use HM-TRS RF transceiver module,but i have a problem
> 
> > with it, i want to send a packet of data to it. The packet include 5
> 
> > bytes,& 60 packets come to RF (HM-TRS)per second,my baud rate is
> 
> > 4800bps.
> 
> > i read the data sheet of HM-TRS & attach its address for you.
> 
> > 
> 
> > http://www.hoperf. com/pdf/HM- TRS.pdf
> 
> > 
> 
> > you should know this RF module must accumulate  32 bytes for every
> 
> > sending of data. but the matter is :
> 
> > 
> 
> > has it at 4800bps continous performance or must accumulate 32 bytes?
> 
> > second state is unpleasant for me because of my data structure.
> 
> > this matter at its data sheet has not determined obviously.
> 
> 
> 
> You should read your own references:
> 
> - The module work mode is half duplex mode. The data will be immediately
> 
> - transmitted as soon as it accumulates 32 bytes in the serial port.
> 
> - When the data is less than 32 bytes, it will transmit again after
> 
> - 30ms. If the data is required to be sent out immediately, make sure it
> 
> - is at least 32 bytes.
> 
> 
> 
> It appears this RF module transmits every 30 mS then spends 5 mS
> 
> changing over to receive mode for a period (probably 20 mS) and then
> 
> another 5 mS back to transmit mode. So it is very likely there is no way
> 
> this RF module can produce the Real Time performance you are expecting.
> 
> 
> 
> Is not clear whether this unit transmits 30 mS after the last byte or 30
> 
> mS after the first byte of its 32 byte buffer. If after the first then
> 
> you will receive two of your 5 byte packets at a time.
> 
> 
> 
> -- 
> 
> David Kelly N4HHE, dkelly@HiWAAY. net
> 
> ============ ========= ========= ========= ========= ========= ========= ======
> 
> Whom computers would destroy, they must first drive mad.
> 
> 
>  
> 
>       
> 
>     
>     
> 	
> 	 
> 	
> 	
> 
> 
> 
> 
> 
> 
> 
> 
> 	
> 
> 
> 	
> 	
> 
> 
>       
> 
> [Non-text portions of this message have been removed]

If you wish to participate in technical forums then you must unlearn bad
email habits. Top-post without trim is poor manners. Trim all but the
parts which relate to the contribution in your reply. Add your
contributions immediately after the parts they relate to. Study the
format of my previous replies and those of David VanHorn for examples.

The following is how *this* (my) reply should have been formed:

On Tue, Jul 28, 2009 at 07:56:33AM -0700, hossein hashemi wrote:
> your last paragraph made i read the data sheet again. if data less
> than 32 bytes exp 25 bytes ,do you think it's transmitted after 30
> ms?(pdf is not clear.)

Yes, the data sheet is not clear. The module either transmits 30 mS
after the first byte of data or 30 mS after the last byte of data, it
does not say.

> it's pleasant for me.
> 25 bytes as a 5 samples of one patient.but this 30ms,for monitoring,
> give a discrete state to data,isn't it?

Am lost in your grammar.

Am a bit frightened that you are collecting data from patients.

You are collecting 5 bytes of data every 16.7 mS. We do not know if the
module will transmit in the middle of your 3rd 5 byte packet or 7th 5
byte packet. It will transmit in the middle of the 3rd if it measures 30
mS from the first byte, or it will transmit in the middle of the 7th
when the buffer contains 32 bytes if it is waiting for 30 mS of nothing
before transmitting.

Either way it can not deliver your data every 16.7 mS, only once every
30 mS. Some of your data will have taken longer to arrive than others..

> but i think i can use the static data for 30ms on monitor. my baud
> rate is 4800bps.but the data sheet hasn't determined? which baud rate
> has this problem.? 

I don't understand "static data".

The data sheet says the RF module will keep up with constant stream of
data at 9600 bps. That if you send faster than 9600 you have to slow the
data, but on closer examination the module has no means of indicating
that data is being sent too fast.

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