Zero bit length of S1 in radio packet mapped to the RAM always

[Hiihtaja]

Hi !
I have configured Zero bit length of S1 in radio packet ( nrf52840 ) but it is still mapped to the RAM.

...
((NRF_S1LEN_BITS << RADIO_PCNF0_S1LEN_Pos) & (RADIO_PCNF0_S1LEN_Msk)) | \
((RADIO_PCNF0_S1INCL_Automatic << RADIO_PCNF0_S1INCL_Pos) & (RADIO_PCNF0_S1INCL_Msk)) |

..

I assume it should be omitted if it 0 bit length. But it present with value 0.

What it can be ?

Regards, Eugene

[Sigurd]

Hi,

I assume NRF_S1LEN_BITS == 0

but it is still mapped to the RAM.

How are you determining and testing this?

[Hiihtaja]

Hello ,

can it be so that I have made wrong interpretation of this feature ?

I have define S1=0 and write entire PCNF0 register in one shot ( Before that I have few reads mask and write back operations).

I can set 3rd position in packet to any value and other node have received this value without any problems.

And I haven't found any anomaly in errata about it.

Regards, Eugene

[Sigurd]

Hiihtaja said:

I can set 3rd position in packet to any value and other node have received this value without any problems.

 But do you get the full length of the payload then? or is the payload missing the last byte?

[Hiihtaja]

Hi !

I think so, I have short custom packet like this:

00 0f f0 1e 04 ff ed 03 00 a2 33 b5 c7 75 7f d7 e2  CRC: 49a5dc. ( CRC OK)

and second byte 0f is the length.

I can't reproduce issue with current setup but I have seen 0x00 instead of f0 at some point.

Regards,

Eugene