New firmware for EmonTX breaks the protocol

[Harri Kapanen]

Hi,

EmonTxV3, the OpenEnergyMonitor transmitter, has a new firmware that changes the protocol: https://github.com/openenergymonitor/EmonTxV3CM

Note: This firmware uses data whitening to improve the reliability of the data transmission. A standard pattern of 1s and 0s is overlayed on the underlying data, this prevents sync issues that result from too many zero values in a packet. When the packet is received it is decoded by emonhub. The 'whitening = 1' is required to tell emonhub to decode the packet correctly.

Any chance supporting this?

Thanks,

Harri

[Benjamin Larsson]

On 2020-03-21 19:22, Harri Kapanen wrote:
> Hi,
>
> EmonTxV3, the OpenEnergyMonitor transmitter, has a new firmware that
> changes the protocol: https://github.com/openenergymonitor/EmonTxV3CM
>

> /Note: This firmware uses data whitening to improve the reliability of

> the data transmission. A standard pattern of 1s and 0s is overlayed on
> the underlying data, this prevents sync issues that result from too many
> zero values in a packet. When the packet is received it is decoded by
> emonhub. The 'whitening = 1' is required to tell emonhub to decode the
> packet correctly.

> /

>
> Any chance supporting this?
>
> Thanks,
>
> Harri

#ifdef RF_WHITENING
byte WHITENING = 0x55;
for (byte i = 0, *p = (byte *)&tmp; i < sizeof tmp; i++, p++)
*p ^= (byte)WHITENING;
#endif


Looks easy to implement but as always we need signal samples before
anyone can do anything.

MvH
Benjamin Larsson

[Harri Kapanen]

On Saturday, March 21, 2020 at 8:30:46 PM UTC+2, Benjamin Larsson wrote:

Looks easy to implement but as always we need signal samples before
anyone can do anything.

While I could learn how to do this, I suspect my 433MHz environment is too crowded for the task. Or does it matter that much in practise?

Harri

[Benjamin Larsson]

Well without any samples there is a near zero chance of anyone fixing
this. Just remove the antenna and the place a device near the rtl-sdr
device and grab a few samples with rtl_433 -S unknown.

MvH
Benjamin Larsson

[Harri Kapanen]

Please find some samples attached - hope this helps. If so, that was surprisingly convenient!

MvH,

Harri

[Harri Kapanen]

Are the samples useful? Anything else I could do?

MvH,

Harri

[Benjamin Larsson]

Den 2020-03-27 kl. 18:15, skrev Harri Kapanen:
> Are the samples useful? Anything else I could do?
>
> MvH,
>
> Harri
>

Yes, you can open a github issue so this is not forgotten.

MvH
Benjamin Larsson

[Harri Kapanen]

Sure, #1342.

MVH,

Harri