added define guard on hci set data length implementation

Author: KMeldgaard

README.md

@@ -21,6 +21,12 @@ STM32Cube_WPAN has several configuration options, which are set in the `app_conf
 This package has a default configuration named `app_conf_default.h`.
 The user can include the file `app_conf_custom.h` to customize the ble application. Options wrapped in `#ifndef, #endif` in `app_conf_default.h` can be overwritten. Additional options can be added.
 
+## HCI data length
+By default the data length (max payload per BLE packet) is set to 27 bytes. This can cause fragmentation when tranmitting large characteristics using a large ATT_MTU.
+To increase the data length user must define `CFG_BLE_ENABLE_SET_DATA_LENGTH` (in `app_conf_default.h`). Further more, the wanted data length must bbe set in same define - eg: `#define CFG_BLE_ENABLE_SET_DATA_LENGTH 251`. Valid range: 27 --> 251.
+**Note: if this is enabled the pheripheral will attempt to increase the HCI data length with every connected device! There is no guarantee all BLE devices support all sizes!**
+Please see
+
 ## License
 
 ```

src/utility/ATT.cpp

@@ -257,7 +257,11 @@ void ATTClass::addConnection(uint16_t handle, uint8_t role, uint8_t peerBdaddrTy
     _eventHandlers[BLEConnected](BLEDevice(peerBdaddrType, peerBdaddr));
   }
   // TODO (krm) increase speed!
-  HCI.hciSetDataLength(handle, 251, 2120);
+  #ifdef CFG_BLE_ENABLE_SET_DATA_LENGTH
+  #if CFG_BLE_ENABLE_SET_DATA_LENGTH < 252 && CFG_BLE_ENABLE_SET_DATA_LENGTH > 26
+  HCI.hciSetDataLength(handle, CFG_BLE_ENABLE_SET_DATA_LENGTH, 2120);
+  #endif // CFG_BLE_ENABLE_SET_DATA_LENGTH < 252 && CFG_BLE_ENABLE_SET_DATA_LENGTH > 26
+  #endif // CFG_BLE_ENABLE_SET_DATA_LENGTH
 }
 
 void ATTClass::handleData(uint16_t connectionHandle, uint8_t dlen, uint8_t data[])

src/utility/HCI.cpp

@@ -672,6 +672,7 @@ void HCIClass::setTransport(HCITransportInterface *HCITransport)
   _HCITransport = HCITransport;
 }
 
+#ifdef CFG_BLE_ENABLE_SET_DATA_LENGTH
 int HCIClass::hciSetDataLength(uint16_t connectionHandle, uint16_t txOctects, uint16_t txTime){
     const uint8_t payload_len = 6;
     const uint16_t opcode = 0x2022;
@@ -685,6 +686,7 @@ int HCIClass::hciSetDataLength(uint16_t connectionHandle, uint16_t txOctects, ui
 
     return sendCommand(opcode, payload_len, cmd_buffer);
 }
+#endif // CFG_BLE_ENABLE_SET_DATA_LENGTH
 
 #if !defined(FAKE_HCI)
 HCIClass HCIObj;

src/utility/HCI.h

@@ -23,6 +23,10 @@
 #include <Arduino.h>
 #include "HCITransport.h"
 
+#if __has_include("app_conf_custom.h")
+#include "app_conf_custom.h"
+#endif
+
 #define BLE_CMD_MAX_PARAM_LEN 255
 
 struct hci_le_set_data_length_cp0{
@@ -82,6 +86,7 @@ class HCIClass {
 
   void setTransport(HCITransportInterface *HCITransport);
 
+  #ifdef CFG_BLE_ENABLE_SET_DATA_LENGTH
   //-----------------------------
   // @brief 
   // @param connectionHandle Connection_Handle Connection handle for which the command applies. 
@@ -96,6 +101,7 @@ class HCIClass {
   //         Values: 0x0148 ... 0x4290
   // @return Value indicating success or error code.
   int hciSetDataLength(uint16_t connectionHandle, uint16_t txOctects, uint16_t txTime);
+  #endif // CFG_BLE_ENABLE_SET_DATA_LENGTH
 
 private:
   virtual int sendCommand(uint16_t opcode, uint8_t plen = 0, void* parameters = NULL);