AVR-Chat

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.


 

      

    
    
	
	 
	
	








	


	
	


      

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