Decryption on fly and S1LEN dependencies

[Hiihtaja]

Hello !

I have found that error free decryption ( MIC error) on fly depends from S1LEN configuration value.

S1LEN have valid range value for each radio mode

2Mbit   1-8

1Mbit   1-6 bit

500K  1-6

125K  1 only

So I have set it to 1 and it work in all radio modes.

Can you explain what is role of S1 byte for triggering decryption on fly  ?

Is any connection of it with preconfigured PPI channel 25 ?

NRF_PPI->CHEN |= (1UL << NRF_PPI_CHANNEL25);

what trigger decrypt process.

Regards,

Eugene

[Sigurd]

Hi,

I assume you set the correct CCM Operation mode:

The only reference to S1 in the CCM docs, is that it's reserved for future use.

infocenter.nordicsemi.com/.../ccm.html

[Hiihtaja]

Hi !

This is problem, PS say it is optional and for future. But without proper S1LEN decryption on fly dosn't work.

And reason is not known. CCM configuration set properly . Not so much variation there,

But can you tell if encryption/decryption on fly MUST work if S1LEN = 0 ?

Regards,

Eugene