Re: [AVR-Chat] wireless transmission help
2008-09-15 by Momen Yousri
Dear Jim
My name is Momen Yousri , I'm a telecommunications and Electronics engineer from Egypt but currently working in the UAE and I was interested in your response regarding the new wireless protocol that achieves syncronization in wireless communications betwwen MCU you are working on right now, and I was wondering if I can help in this project.
I've worked on the Atmega8515 MCU where we used it to make image compression using the wavelet transform and it gave very promising results, we used the matlab as the host program to download and the pic required to be compresed using the RS323 interface and the MCU makes processing and memory managment to perform the wavelet transform and upload it again to the Matlab and display the result picture. Our pictures were grayscale with dimensions 128X128 pixels.
I also worked on the 8088 and the AT80C52 MCU and have a handfull knowlege of Assembly programming and serial port interface and communications.
Eng. Momen Yousri Mohamed
Telecommunications and Electronics Engineer
Three Phase Electricwondering if I can give any help in this projectal
Sharjah,UAE
00971508152464Show quoted textHide quoted text
----- Original Message ----
From: Jim Wagner <wagnerj@proaxis.com>
To: AVR-Chat@yahoogroups.com
Sent: Monday, September 15, 2008 1:06:27 AM
Subject: Re: [AVR-Chat] wireless transmission help
On Sep 13, 2008, at 5:10 PM, jerson.millora wrote:
> I am currently working for a project
>
> It is a controller for poultry houses...
> It will basically regulate the temperature, humidity, and other
> conditions. It will also schedule the feeding of the chickens...
>
> It has sensors (temp, humidity). The signals from the sensors will be
> transmitted wirelessly to the controller.
>
> This is the block diagram
>
> http://i174. photobucket. com/albums/ w95/ ... tled-1.jpg
> <http://i174. photobucket. com/albums/ w95/jerson_ millora/Untitled -1.jpg>
>
> I will be using ATtiny13 or ATtiny45 for the transmitter side and
> ATMEGA16 for the controller side...
>
> My problem is the synchronization between the transmitter and receiver
> part.. How am i suppose to interface the transmitter and receiver to
> the
> AVRs? The transmitter and receiver receive and send data serially.
> Can I
> use general i/o to this one?
>
> [Non-text portions of this message have been removed]
>
>
>
Some wireless devices can be driven directly from a UART or provide a
received signal directly to a UART input. That part is NOT hard.
The harder part is what you refer to as "synchronization" ., That
required designing an appropriate protocol. I am in the process of
doing such a thing right now, maybe to become open source. But, it is
NOT ready to share.
If you will ONLY have one remote device and one "master", then it is
much simpler. The master just listens all the time and the slave sends
when ever it wants. This way, the remote can use battery power and
sleep between transmissions. The master is more likely to have a
steady source of power in your situation so listening all the time
should not hurt.
What you could do is have the slave listen for a while after each
transmission. Then, the master waits until it hears a message from the
slave. When that message is done, it sends any return message to the
slave. This still allows the slave to sleep most of the time because
it "knows" when a message will be received, if there is one to be
received.
A message MIGHT consist of one or more "preamble" characters, a
"framing" character that signifies the start of the data, a fixed
number of data bytes, a CRC or checksum. and an ending framing
character. This is certainly NOT the only way to do it.
Hope this helps,
Jim
Jim Wagner
Oregon Research Electronics
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