4.1.1.2 Bluetooth®LE Legacy Scan

This section explains how to enable the BLE Scanning on the PIC32WM-BW1 Curiosity board using MCC. BLE scanning is utilized to detect devices that are in advertising mode. Within BLE protocols, the process is initiated by either a central device or an observer engaging in scanning activities.

Users can choose to either run the precompiled application example hex file provided on the PIC32WM-BW1 Curiosity Board or follow the steps to develop the application from scratch.

Hardware Requirement

Software

• To install Tera Term tool, refer to the Tera Term web page listed in the Reference Documentation from Related Links.

Programming the Precompiled Hex File or Application Example

Using MPLAB® X IPE:

1. Precompiled .hex file is located in <Harmony Content Path>\wireless_apps_pic32_bw1\apps\ble\central\central_legacy_scan\hex folder.

2. For detailed steps, refer to Programming a Device in MPLAB® IPE in Reference Documentation from Related Links.
   Note: Ensure to choose the correct Device and Tool information.

Using MPLAB® X IDE:

1. Perform the following the steps mentioned in Running a Precompiled Example. For more information, refer to Running a Precompiled Application Example from Related Links.
2. Open and program the application example legacy_scan.X located in <Harmony Content Path>\wireless_apps_pic32_bw1\apps\ble\central_legacy_scan\firmware..

3. For more details on finding the Harmony content path, refer to Installing the MCC Plugin from Related Links.

Testing

Project Graph

Verifying the Scan Configuration

1. Click on the BLE Stack component in project graph and configure as illustrated in the following figure.

   

Generating a Code

For more details on code generation, refer to MPLAB Code Configurator (MCC) Code Generation from Related Links.

Files and Routines Automatically generated by the MCC

After generating the program source from MCC interface by clicking Generate Code, the BLE configuration can be found in the following project directories:

The OSAL, RF System, BLE System initialization routine executed during program initialization can be found in the project files. This initialization routine is automatically generated by the MCC.

The BLE stack initialization routine executed during Application Initialization can be found in project files. This initialization routine is automatically generated by the MCC. This call initializes and configures the GAP, GATT, SMP, L2CAP and BLE middleware layers.

Header Files

• ble_gap.h: This header file contains BLE GAP functions and is automatically included in the app.c file

Function Calls

MCC generates and adds the code to initialize the BLE Stack GAP, GATT, L2CAP and SMP in APP_BleStackInit() function

• APP_BleStackInit() is the API that will be called inside the applications initialization state APP_STATE_INIT in app.c

User Application Development

1. Include

   1. Include the user action. For more information, refer to User Action from Related Links.
   2. definitions.h in all the files where UART will be used to print debug information.

      Note: definitions.h is not specific to just UART peripheral, instead it must be included in all application source files where peripheral functionality will be exercised.

2. Start Scanning in app.c

   This API is called in the application’s initialization state - APP_STATE_INIT in app.c. Scan duration is 10 seconds.

   // Scanning Enabled
   BLE_GAP_SetScanningEnable(true, BLE_GAP_SCAN_FD_ENABLE, BLE_GAP_SCAN_MODE_OBSERVER, 100);
   //Output the status string to UART
   SERCOM0_USART_Write((uint8_t *)"Scanning \r\n", 11);

   

3. Scan Results in app_ble_handler.c

     #include "definitions.h"
   uint8_t scanAddr[12];
   
   static void APP_HexToAscii(uint8_t byteNum, uint8_t *p_hex, uint8_t *p_ascii)
   {
       uint8_t i, j, c;
       uint8_t digitNum = byteNum * 2;
   
       if (p_hex == NULL || p_ascii == NULL)
           return;
   
       for (i = 0; i < digitNum; i++)
       {
           j = i / 2;
           c = p_hex[j] & 0x0F;
   
           if (c >= 0x00 && c <= 0x09)
           {
               p_ascii[digitNum - i - 1] = c + 0x30;
           }
           else if (c >= 0x0A && c <= 0x0F)
           {
               p_ascii[digitNum - i - 1] = c - 0x0A + 'A';
           }
   
           p_hex[j] /= 16;
       }
   }
   

4. In APP_BleGapEvtHandler(), case BLE_GAP_EVT_ADV_REPORT:

   BLE_GAP_EvtAdvReport_T scanResults;
   scanResults.addr = p_event->eventField.evtAdvReport.addr;
   APP_HexToAscii(6, scanResults.addr.addr, scanAddr);
   SERCOM0_USART_Write((uint8_t *)"0x", 2);
   SERCOM0_USART_Write((uint8_t *)scanAddr, 12);
   SERCOM0_USART_Write((uint8_t *)"\r\n", 2);

   

5. Scan Timeout Event

   • In app_ble_handler.c, BLE_GAP_EVT_SCAN_TIMEOUT event is generated when BLE Scan duration expires. In case BLE_GAP_EVT_SCAN_TIMEOUT add following:

     SERCOM0_USART_Write((uint8_t *)”Scan Completed \r\n”, 17);