Manchester (biphase) protocol for AVR microcontrollers

[RES]

I want to transmit data (by air) with a RX/TX 433MHz set, and want to
use Manchester coding/encoding.
I only know that a logic 0 is a signal going from 0 to 1 (upward
transition at bit centre), and a logic 1 visa versa.
But must this happen in the transmitter, receiver or both ?

What is the best way to get the transmission errorfree (I think about
startbits, checksums ?) How can this all be accomplished ?

I have my transmitter and receiver operating, I can already transmit a
steady signal. The speed I want to transmit on is 2400 baud.
I've made a little test code:

waitHi: sbis ACSR, ACO ;wait for hi level
rjmp waitHi
sbi PORTD, LED


This works good. As soon as I switch on the transmitter the LED goes
on.
Anyone more info, tips & tricks, a FAQ, etc. ?

Thanks.

 

[Terran Melconian]

In article <3e2f7529.0405311025.4dc2234f@posting.google.com>,
RES <at90s2313@europe.com> wrote:

But must this happen in the transmitter, receiver or both ?

You need to encode the data in the transmitter and then decode it again
in the receiver. The procedures for doing this will not be exact
opposites of each other because of the need to recover the clock in the
receiver. You should start by doing a search for more information on
manchester encoding. Here's a place to start:

http://www.google.com/search?q=manchester+encoding

The first hit looked good to me, and even included a description of how
to implement a simple PLL on your uC.

What is the best way to get the transmission errorfree (I think about
startbits, checksums ?) How can this all be accomplished ?

First you need more practice programming your microcontroller. The
confusion and lack of direction you're experiencing means you're trying
to do something which is still too hard for you. Work on some simpler
projects first, like making your LED blink at various rates and then
blink out a message.

Anyone more info, tips & tricks, a FAQ, etc. ?

For general AVR information and tips, try http://www.avrfreaks.net/