S0 and S1 fields

[George555]

Hello.

I'm reading the documentation of the radio peripheral of nRF52832 but I can't find any information about the S0 and S1 fields.

What are those fields? What do they mean?

[Dmitry]

Hi,
these fields allow radio to work with different protocols and packet formats.
S0 is a part of packet preceding length field (e.g. in BLE, length field is the second byte). Thus receiver/transmitter knows where to look for packet length.
S1 is to handle cases when packet header is not a multiple of byte (in ESB, for example, PCF field is 9 bits wide).

[George555]

Thanks Dmitry,

Do I need to use them in case I want to implement my own protocol with static or dynamic payload length?

I have modified a simple example with static packet payload length and it works fine. I'm just not sure if I need those fields.

[Dmitry]

If you have length field encoded in the first byte of packet, or payload length is static, you don't need S0.
S1 is only needed as padding if your LENGTH field is less than 8 bits (I believe it's not).

[George555]

In the example I used as a base, S0, S1, and LENGTH fields are equal 0.