How do I send MANCHESTER encoded data over serial comm?

Hi All,

I am wondering how I can really send MANCHESTER encoded data over serial comm.

I'm tuning up a project involving the use of RF modules (such as TLM434) where MANCHESTER coding makes it possible to use them. Actually it works, but not with 100% reliability; in fact, it's much, very much less.

For any reason, I didn't notice up to now that my MANCHESTER encoded sent data doesn't really look like to be MANCHESTER encoded.

Attachment 8834

Where in the green square I send "U" characters as a preamble (%01010101), the "MANCHESTER encoded" data (see a piece of it in the orange square) shouldn't, IMHO, look like this.

This is the way I send the data:
...where Encoded is a WORD variable (containing i.e.: 182 => 10110110 => 1001101001101001).

MANCHESTER coding should format the data to be at a maximum of two similar logic signals in a row (or I got it wrong).

Where a "0" or a "1" lasts (in this example @ 4800bps) 0.2ms as seen in the green square, a "00" or "11" MANCHESTER encoded sequence should not be greater than 0.4ms. But, as you can see in the orange square, this low state lasts 0.8ms meaning I send four zeros in a row (!?).

So, how do I do this?

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