I have a custom BLE peripheral/server that uses nRF52832 + SDK11.0.0 + s132_2.0.0. It can stream notification data indefinitely without any issue. The notification packets are 20B long (max MTU is 23B) and the data is sequential 3 byte integer values starting at the 3rd byte. The first two bytes are a packet counter (0-255) and a packet ID (used by SW). Thus the first packet would be [00 0b 00 00 00 00 00 01 00 00 02 00 00 03 00 00 04 00 00 05] and the second packet would be [01 0b 00 00 06 00 00 07 00 00 08 00 00 09 00 00 0a 00 00 0b]. The data rate is ~6kBps of user data.
I upgraded the FW to SDK17.0.2 + s132_7.2.0 and it has an issue where notification packets are intermittently repeated and then what was supposed to be the next packet is not sent, but instead the subsequent packet is sent. For example, if the 2nd packet in the packet description given above was missed, I'd get [00 0b 00 00 00 00 00 01 00 00 02 00 00 03 00 00 04 00 00 05] followed by another [00 0b 00 00 00 00 00 01 00 00 02 00 00 03 00 00 04 00 00 05] then [02 0b 00 00 0c 00 00 0d 00 00 0e 00 00 0f 00 01 00 01 01]. The [01 0b 00 00 06 00 00 07 00 00 08 00 00 09 00 00 0a 00 00 0b] packet would be missed completely.
The FW logic is the same in both cases and I have a queue to hold the notification data to be sent on BLE_GATTS_EVT_HVN_TX_COMPLETE if NRF_ERROR_RESOURCES (SDK17.0.2) or BLE_ERROR_NO_TX_PACKETS (SDK11.0.0) occurs. Slowing down the data rate doesn't help the issue. The issue seems to occur more often when using 2Mbps PHY. The central/client is a Windows PC. Kindly advise on what is causing this issue. Thanks!
PS. I would like to enable 2Mbps PHY on the SDK11.0.0 + s132_2.0.0 version to see if that causes the issue with that SDK. How do I do this?
