BLE: ESP32 to NimBLE, shared BLE helpers, non-blocking nRF52 sends

platformio.ini

@@ -62,8 +62,13 @@ monitor_filters = esp32_exception_decoder
 extra_scripts = merge-bin.py
 build_flags = ${arduino_base.build_flags}
   -D ESP32_PLATFORM
+  -D CONFIG_BT_NIMBLE_ROLE_CENTRAL_DISABLED
+  -D CONFIG_BT_NIMBLE_ROLE_OBSERVER_DISABLED
+  -D CONFIG_BT_NIMBLE_MAX_CONNECTIONS=1
 ;  -D ESP32_CPU_FREQ=80          ; change it to your need
 build_src_filter = ${arduino_base.build_src_filter}
+lib_deps = ${arduino_base.lib_deps}
+  h2zero/NimBLE-Arduino @ 2.5.1
 
 [esp32_ota]
 lib_deps =

src/helpers/SerialBLECommon.h

@@ -0,0 +1,95 @@
+#pragma once
+
+#include "BaseSerialInterface.h"
+#include <stdio.h>
+#include <string.h>
+
+// Nordic UART service
+#define BLE_UART_SERVICE_UUID  "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
+#define BLE_UART_RX_UUID       "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
+#define BLE_UART_TX_UUID       "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
+
+// Units: interval=1.25ms, timeout=10ms
+#define BLE_MIN_CONN_INTERVAL      12
+#define BLE_MAX_CONN_INTERVAL      36
+#define BLE_SLAVE_LATENCY          3
+#define BLE_CONN_SUP_TIMEOUT       500
+
+// Units: advertising interval=0.625ms
+#define BLE_ADV_INTERVAL_MIN       32
+#define BLE_ADV_INTERVAL_MAX       338
+#define BLE_ADV_FAST_TIMEOUT       30   // seconds
+
+#define BLE_MAX_MTU                247   // nRF52 max
+#define BLE_DLE_MAX_TX_OCTETS      251
+
+#define BLE_FRAME_QUEUE_SIZE       2048   // bytes: frames are packed by size, so a burst of small commands fits
+
+// name is IN/OUT: "@@MAC" is replaced by the address in hex, printed addr[0] first (or addr[5] first if reversed)
+inline void makeBLEName(char* dev_name, size_t size, const char* prefix, char* name, const uint8_t addr[6], bool reversed) {
+  if (strcmp(name, "@@MAC") == 0) {
+    for (int i = 0; i < 6; i++) {
+      sprintf(&name[i * 2], "%02X", addr[reversed ? 5 - i : i]);
+    }
+  }
+  snprintf(dev_name, size, "%s%s", prefix, name);
+}
+
+struct SerialBLEFrame {
+  uint8_t len;
+  const uint8_t* buf;
+};
+
+// single producer / single consumer ring, so the BLE task may push while the main loop pops (and clears).
+// Frames are stored as [len][bytes] and never wrap, so peek() hands out one contiguous buffer.
+template <uint16_t N>
+class SerialBLEFrameQueue {
+  static_assert(N > 2 * (MAX_FRAME_SIZE + 1), "queue too small");   // any frame fits once empty
+  static const uint8_t WRAP = 0xFF;   // as a length: rest of the buffer unused, continue at 0
+  uint8_t _buf[N];
+  volatile uint16_t _head = 0, _tail = 0;   // read and write offsets, equal when empty
+
+public:
+  void clear() { _head = _tail; }
+  bool isEmpty() const { return _head == _tail; }
+  uint16_t used() const { uint16_t h = _head, t = _tail; return t >= h ? t - h : N - h + t; }
+
+  // caller ensures len <= MAX_FRAME_SIZE
+  bool push(const uint8_t* src, size_t len) {
+    uint16_t h = _head, t = _tail, need = len + 1, at = t;
+    if (t < h) {
+      if (need >= h - t) return false;   // a full ring must not look empty
+    } else if (N - t < need + (h == 0)) {
+      if (need >= h) return false;
+      at = 0;
+    }
+    _buf[at] = len;
+    memcpy(&_buf[at + 1], src, len);
+    if (at != t) _buf[t] = WRAP;
+    __sync_synchronize();
+    _tail = (at + need) % N;
+    return true;
+  }
+  SerialBLEFrame peek() const {
+    uint16_t h = _head;
+    if (_buf[h] == WRAP) h = 0;
+    return { _buf[h], &_buf[h + 1] };
+  }
+  void pop() {
+    uint16_t h = _head;
+    if (h == _tail) return;
+    if (_buf[h] == WRAP) h = 0;
+    h = (h + 1 + _buf[h]) % N;
+    __sync_synchronize();
+    _head = h;
+  }
+};
+
+#if BLE_DEBUG_LOGGING && ARDUINO
+  #include <Arduino.h>
+  #define BLE_DEBUG_PRINT(F, ...) Serial.printf("BLE: " F, ##__VA_ARGS__)
+  #define BLE_DEBUG_PRINTLN(F, ...) Serial.printf("BLE: " F "\n", ##__VA_ARGS__)
+#else
+  #define BLE_DEBUG_PRINT(...) {}
+  #define BLE_DEBUG_PRINTLN(...) {}
+#endif