Unify nRF & ESP BLE interface

[liquidraver]

Core Stuff

• Unified common code into SerialBLECommon.h base class
  (it should reside in a helpers/bluetooth folder with all the nrf/esp files, but this PR is not for tidying up)

• ESP32: Migrated from ESP32 BLE library to NimBLE - Re-pair could be needed! Full erase would be preferable for updating to clear out old BT library stuff from the flash. Factory reset does not clear that.

  • this also resolves xiao c3 bootloops because of too much sensors (-~500k from flash)

Connection

• Reject second connection attempts (single connection only) (edge case!)
• Improved disconnect handling with reason codes and initiator tracking (for debugging who is to blame for disconnects)

Dynamic connection parameters

• Added sync mode: switches to low-latency params (0 latency, 12-24ms interval) for high throughput
• Sync mode when the fw auto-detects large frame activity (40+ bytes, 3+ frames in 1.5s window)
• Falls back to default mode (3 latency, 12-36ms interval) after 5s inactivity
• Tracks connection parameter updates via BLE events

Queue & Transfer Improvements

• Circular queue implementation replaces linear array shifts - less RAM/CPU
• Added send interval throttling (8ms minimum) - undetectable by user, but helps stabilize the ble stack, on ESP this is mandatory!
• Improved retry logic with throttle window (250ms) - throttle sending when we detect spotty BT connection

ESP32 Specific:
Well... everything that nRF had already are now in ESP's interface :) even "turbo mode"

The two platform's BLE interface is now more or less the same (with library dependent differences of course)

[fdlamotte]

well did a first test with thinknode M5 ... it connects but I have no response to APPSTART :(

I have an heltec_v3, I'll try with it ...

update: I erased the device, removed it from the PC and did the pairing again ... now I can connect

Is it necessary to to a full erase before using it with the new lib ?

[liquidraver]

well did a first test with thinknode M5 ... it connects but I have no response to APPSTART :(

I have an heltec_v3, I'll try with it ...

update: I erased the device, removed it from the PC and did the pairing again ... now I can connect

Is it necessary to to a full erase before using it with the new lib ?

On my test devices it was not necessary, but the MAC is the same and bluetooth keys on ESP are on the NVS partition, they can conflict. A factory reset won't erase that.

On paper IDF and nimBLE does not use the same namespace on NVS, but it can cause hard-to-debug bugs.
(we should add NVS erase to our factory reset function, so it will mean the same as on nRF, i.e.: completely clean slate)

Completely ditching ESP-IDF and using a brand new lib so starting fresh on flash is recommended.

[ripplebiz]

Nice work!