I have the NRF_CCM peripheral setup to encrypt packets on-the-fly. I can verify packets are properly encrypted when the payload size is 27 bytes or smaller. However, anything greater than 27 bytes of payload is truncated. I can see in the encrypted buffer pointed to by NRF_CCM->OUTPTR contains the correct length (non-truncated length, with the +4 MIC length).
I expected this issue may be a result of the extended length setting in NRF_CCM. But have the bit correctly enabled.
NRF_CCM->MODE = ((uint32_t)CCM_MODE_MODE_Encryption << CCM_MODE_MODE_Pos ) |
((uint32_t)CCM_MODE_DATARATE_1Mbit << CCM_MODE_DATARATE_Pos ) |
((uint32_t)CCM_MODE_LENGTH_Extended << CCM_MODE_LENGTH_Pos );
I have also checked the max length register. I used various values in this register to see if I can get a different response. But the result is an OTA max value of 27 bytes.
NRF_CCM->MAXPACKETSIZE = (uint32_t)0xFB;
From another forum post, I can see that toggling the enable can help. I tried this too but to no avail.
NRF_CCM->ENABLE = ((uint32_t)CCM_ENABLE_ENABLE_Disabled << CCM_ENABLE_ENABLE_Pos );
NRF_CCM->ENABLE = ((uint32_t)CCM_ENABLE_ENABLE_Enabled << CCM_ENABLE_ENABLE_Pos );
I have also verified the KSGEN is triggered well in advance of READY. I measured 251-us. Image attached below.
Any alternative debugging tips would be appreciated. Thanks in advance.
