How can i add a 2-byte transmit header to the wireless message.

[Bvan .9]

Hello,

I am trying to get the NUCLEO-WL55JC radio backwards compatible with our previous radios protocol used in the SI4432 and the EFR32xx from silicon labs. Most of it is already working but I can not add a transmit header in the message. This transmit header are two extra control bytes placed between the sync-word and the length byte.

 

The transmit header is included in the CRC and data whitening, so I can not combine the transmit header with the sync word.

Is there any possibility to add these two bytes in the wireless message, I do not care if I have to manually check the transmit header and/or packet length. The main goal is to make this radio backwards compatible.

Some radio information:

-         GFSK modulation

-         868 MHz base frequency

-         2 bytes sync-word

-         2 bytes transmit header

-         1 bytes packet length

-         Variable packet length

-         CRC16

-         Using CRC over: Transmit header, Packet length and data.

-         Using data whitening over: Transmit header, Packet length, data and CRC.

[YBOUV.1]

Hi @Bvan .9​ ,

You can do that manually indeed.

You can find some useful material below, although not complying entirely with your packet format requirements:

https://www.st.com/resource/en/application_note/an5687-longpacket-operation-with-stm32cubewl-stmicroelectronics.pdf

[Bvan .9]

Hi @YBOUV.1​ ,

I've managed to do this manually and I can succesfully transmit messages, thank you for your help and information.