Manchester using DFSDM

[LMore.2]

A lot of documents report that is possible to use DFSDM to encode and decode Manchester.

Unfortunately i'm not able to find any example code.

Any suggestion?

[waclawek.jan]

*Encode*?

> A lot of documents

Post links.

DFSDM in some incarnations can decode Manchester stream, to be fed into its filter. Most likely not what you want.

JW

[LMore.2]

Ciao JW

You are right!

Documents talk about manchester protocol, but it is only for decoding, not encoding.

In any case decoding is just what I need.

My needs is to decode 8 manchester line.

I have already implemented the decoder by software for one line, but it is very CPU consuming.

Duplicate it for both 8 line don't seems a smart approach.

DFSDM seems the right solution, decoding in hardware and STM32F767 should decode 8 manchester lines.

This cpu is not mandatory, I have a Nucleo board using this CPU so I'm using it for my prototype.

Unfortunately is my first time that I use DFSDM and I'm really confused about how it is works.

Some example code could help me too much. But I'm not able to find nothing...

Also some tutorial for dummy could help!

Can you help me?

Thanks.

Luca

Da: ST Community [mailto:

Oggetto: waclawek.jan answered you: Manchester using DFSDM

*Encode*? > A lot of documents Post links. DFSDM in some incarnations can decode Manchester stream, to be fed into its filter. Most likely not what you want. JW

*Encode*?

> A lot of documents

Post links.

DFSDM in some incarnations can decode Manchester stream, to be fed into its filter. Most likely not what you want.

JW

> Wednesday, September 23, 2020 11:52 AM

Manchester using DFSDM

A lot of documents report that is possible to use DFSDM to encode and decode Manchester.

Unfortunately i'm not able to find any example code.

Any suggestion?

DFSDM in some incarnations can decode Manchester stream, to be fed into its filter. Most likely not what you want.

JW

[waclawek.jan]

The output of the decoder goes immediately to the filter which performs the Delta-Sigma demodulation. There is no way to access the decoded data stream, AFAIK. It is maybe sad, but that's how things are.

Under certain circumstances, software decoding may be possible. Tell us details of your application, e.g. are the streams synchronous, are they continuous, are there any markers, is the baudrate known/stable, is the link noisy, etc.

JW

[LMore.2]

Hi,

in attach you can find an frame example that I have to decode.

This frame is transmitted from a RF transponder.

The needed is to have 8 connections (DFSDM should handle 8 line).

The frame is transmitted 5 time, whit no delay between frame.

Baudrate is fixed, 32us each bit:

- Start bit is 32us high

- 10 data bit, encoded in manchester

- Stop bit 32us low

Let me know if you need more detail.

Thanks in advanced.

Luca

Oggetto: waclawek.jan answered you: Manchester using DFSDM

The output of the decoder goes immediately to the filter which performs the Delta-Sigma demodulation. There is no way to access the decoded data stream, AFAIK. It is maybe sad, but that's how things are. Under certain circumstances, software decoding may be possible. Tell us details of your application, e.g. are the streams synchronous, are they continuous, are there any markers, is the baudrate known/stable, is the link noisy, etc. JW

> (Community Member)

The output of the decoder goes immediately to the filter which performs the Delta-Sigma demodulation. There is no way to access the decoded data stream, AFAIK. It is maybe sad, but that's how things are.

Under certain circumstances, software decoding may be possible. Tell us details of your application, e.g. are the streams synchronous, are they continuous, are there any markers, is the baudrate known/stable, is the link noisy, etc.

JW

> Wednesday, September 23, 2020 11:52 AM

Manchester using DFSDM

A lot of documents report that is possible to use DFSDM to encode and decode Manchester.

Unfortunately i'm not able to find any example code.

Any suggestion?

Under certain circumstances, software decoding may be possible. Tell us details of your application, e.g. are the streams synchronous, are they continuous, are there any markers, is the baudrate known/stable, is the link noisy, etc.

JW

[waclawek.jan]

I don't see any attachment. You may want to go to the web rather than answering through mail.

What you mention is the most generic case - mutually independent channels, no common clock, RF thus noisy. Thus, I don't think there is any trick to do this simpler than perform full decode for all channels in software.

JW

[LMore.2]

Before I reply using standard email and probably the image was ignored...

To be more precise, the application is the "time detection" used in race (car, motor, bicycle, etc etc)

8 independent channel, no common clock, fixed Bit length to 32uS.

I have already implemented in software the decoding for one line. Just for fun i'll try to do the same for eighth line... Probably discovering that is too much work for the CPU.

In the meantime I have ordered a FPGA to implement decoding in hardware.

thanks for all

Luca