3.1.1.2 BLE Legacy Scan

Introduction

This section helps users to enable the BLE Scanning on the WBZ451 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 of this document can choose to just run the precompiled Application Example hex file on the WBZ451 Curiosity Board and experience the demo or can go through the steps involved in developing this application from scratch

Recommendation is to follow the examples in order, by learning the basic concepts first and then progressing to the more advanced topics.

Recommended Reading

1. BLE Software Specification

2. FreeRTOS BLE App Initialize

3. Adding UART

Hardware Requirement

SDK Setup

• Getting Started with Sofware Development

Software

• Tera Term

Smartphone App

None

Programming the Precompiled .hex File or Application Example

Programming the .hex file using MPLAB X IPE

1. Precompiled .hex file is located in the path “<Harmony Content Path>\wireless_apps_pic32cxbz2_wbz45\apps\ble\building_blocks\central\legacy_scan\hex” folder

2. For more details on the steps, go to Programming A Device.

   Note: Users must choose the correct Device and Tool information.

Programming the Application using MPLAB X IDE

1. Follow steps mentioned in of Running a Precompiled Example section.

2. Open and program the application example legacy_scan.X located in "<Harmony Content Path>\wireless_apps_pic32cxbz2_wbz45\apps\ble\building_blocks\central\legacy_scan\firmware" using MPLAB X IDE

For more details on finding the Harmony content path, refer to Installing the MCC Plugin section.

Demo Description

This application example enables users to do passive scanning. After programming the application example, on Reset user will be able to see the beginning of scan operation, The Bluetooth addresses of devices will be scanned for the next 10 seconds. After 10 seconds the scanning operation will complete.

Testing

Users can use another WBZ451 Curiosity Board configured as BLE Advertiser set the address and scan

Developing this Application from Scratch Using MCC

1. Create a new MCC Harmony Project. For more details, refer to Creating a New MCC Harmony Project section.

2. Import component configuration: This step helps users to setup the basic components and configuration required to develop this application. The imported file is of format .mc3 and is located in the path "<Harmony Content Path>\wireless_apps_pic32cxbz2_wbz45\apps\ble\building_blocks\central\legacy_scan\firmware\legacy_scan.X".

   For more details on importing the component configuration , refer toImporting Existing App Example Configuration

3. Accept dependencies or satisfiers, select Yes.

4. Verify if the project graph window has all the expected configuration , as illustrated in the following figure

   

Verifying the Scan Configuration

1. Click on the BLE Stack component in project graph, to open component configuration 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.

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.

Auto generated, Scan Parameters

Note: app.c is autogenerated and has a state machine based application code sample, users can use this template to develop their application

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

Include

• User action is required as mentioned here

• 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

Start Scanning

// 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);

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

Scan Results

• BLE_GAP_EVT_ADV_REPORT event is generated upon finding advertisements on legacy channels

  // code snippet to print scan results
  uint8_t scanAddr[12]; //var to store ASCII address
  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);

// function to convert HEX to ASCII
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;
    }
}

Add the above code to the appropriate sections within the app_ble_handler.c

Scan Timeout Event

• In app_ble_handler.c, BLE_GAP_EVT_SCAN_TIMEOUT event is generated when BLE Scan duration expires.

  • Add the following code, inside BLE_GAP_EVT_SCAN_TIMEOUT case.

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

  

Users can exercise various other BLE Advertisement functionalities by using BLE Stack API

For more details, refer to BLE Connection.