4.1.2.4 BLE Deep Sleep Advertising

Introduction

This document will help users to enable "Deep sleep" mode with BLE Advertisements on WBZ351 Curiosity board using MPLAB Code Configurator(MCC). In this basic application example the Deep Sleep advertisement interval will be set to 1000 millisecond. The advertisement interval will dictate the application Deep sleep time.

Users of this document can choose to just run the precompiled Application Example hex file on the WBZ351 Curiosity Board and experience the demo or can go through the steps involved in developing this Application from scratch.

These examples each build on top on one and other. We strongly recommend that you follow the examples in order, to learn the basics concepts before progressing to the more advanced topics.

Recommended Reads

Hardware Required

SDK Setup

Software

Smartphone App

Programming the precompiled hex file or Application Example

Programming the hex file using MPLABX IPE

1. Precompiled Hex file is located in "<Harmony Content Path>\wireless_apps_pic32cxbz2_wbz45\apps\ble\building_blocks\peripheral\deep_sleep_adv\hex" folder

2. Follow the steps mentioned here

Caution: Users should choose the correct Device and Tool information

Programming the Application using MPLABX IDE

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

2. Open and program the Application Example "ble_deep_sleep_adv.x" located in "<Harmony Content Path>\wireless_apps_pic32cxbz2_wbz45\apps\ble\building_blocks\peripheral\deep_sleep_adv\firmware" using MPLABX IDE

<Harmony Content Path> how to find what is my Harmony Content Path

Demo Description

This Application Example enables users to enter Deep sleep mode while transmitting Connectable, Undirected BLE Advertisements. On power on reset application will enter "Deep Sleep Mode". When the USR-BTN 2(SW2) is pressed, the device on-board LED(green) starts blinking to denote start of advertisements. The device will enter into Deep sleep mode periodically based on the advertisement interval. The advertisement interval is set to 1000 milliseconds for this example. When device connects with the mobile App the onboard led start to glow solid, which indicates the connection established and the device will enter Standby Sleep Mode during Idle state.

Testing

Connect the WBZ351 Curiosity board to PC, program the precompiled hex file or application example as mentioned. Upon flashing, there will not be any indication on the board, since the device enters deep sleep mode. User can press the USR-BTN 2(SW2) available on the board to start Deep sleep Advertising. To connect to the WBZ351, User can open the Microchip Bluetoth Data App on Smartphone. Select the BLE Smart sub app to see the scan results. Device name "BLE_DSADV" will appear.

Current Consumption Measurement

Connect the Multimeter/Power Debugger to Power Measurement Header J6. Power on the Board. If using Power Debugger, users can use Data Visualizer to measure the current consumption.

Current measured in Deep sleep mode is around 1.9 uA.

Current measured in Deep sleep + Advertising mode is around 130 uA average.

Users of this Early adopter package should go through the known issues document and understand the limitations if any with the current low power mode implementation.

Developing the application from scratch

1. Developing this Application using MPLAB Code Configurator Import method
2. Developing this Application from scratch using MPLAB Code Configurator

Developing this Application using MPLAB Code Configurator Import method

This section explains the steps required by a user to develop this application example using MPLABx Code Configurator import method.

Developing this Application from scratch using MPLAB Code Configurator

This section intented to showcase the complete application development from the scratch including the individual component and its dependency inclusion.

1. Create a new MCC Harmony Project -- Refer to new MCC Project Creation

2. In the previous step, the BLE Stack component is included. Accept all the component auto-activation and attachment auto-connect confirmation.
   
3. Include the RCON Component from the peripheral category.
   

4. Include the Transparent Service and Transparent Profile component located at :Harmony-> Wireless->Drivers->BLE

   Establish the link between the Transparent Service and Profile

   

   Click on the "Transparent Profile" component. In the configuration option, enable server role

   

5. Click on the BLE Stack component present in the project graph. A configuration option window will get open.

   Enable the check box for "Enable Sleep Mode" option.

   

   This action will trigger the auto inclusion of the RTC component . Accept the confirmation and auto-connect request.

   
6. Final Project graph with all the required component

   

Component configuration settings

Generate Code

Now all the required components has been added to the project and necessary configuration modification is made. The next step is to generate the application code.

To generate the project, follow the instruction on how to Generate Code

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

During system sleep, clock (system PLL) will be disabled and system tick will be turned off. FreeRTOS timer needs to be compensated for the time spent in sleep. RTC timer which works in the sleep mode is used to accomplish this. RTC timer will be initialized after BLE stack initialization.

Header Files

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

Function Calls

• APP_BleStackInit() and APP_BleDsadvStart(flag) are the API's that will be called inside the Applications Initial State -- APP_STATE_INIT in app.c.

Manual Application code edit

This section talks about the mandatory code modifications that needs to be incorporated inorder to implement the deep sleep Advertising functionality.

Step 1: app_user_edits.c

• Some of the Harmony 3 generated files cannot be fully configured by the MPLABX Code Configurator. This file contains the instructions for the user to modify these files.

  Follow the instruction mentioned on the app_user_edits.c file and after completing the required edits, comment out or remove the #error line

Step 2 - Initialization.c

• Comment the code inside SYS_Initialize function

  In the MCC Generated code, the CLK_Initialize and ROM functions are by default present inside SYS_Initialize function in Initialization.c file. The user needs to comment out the code referring to CLK_Initialize and ROM functions in SYS_Initialize function and should add under _on_reset() function in same initialization.c file.

  

• Code Inclusion inside _on_reset function

  The previously commented code inside SYS_Initilaze function is included here

  

  CLK_Initialize(); 
      typedef int (*FUNC_PCHE_SETUP)(uint32_t);
      ((FUNC_PCHE_SETUP)(*(uint32_t*)0xF2D0))((PCHE_REGS->PCHE_CHECON & (~(PCHE_CHECON_PFMWS_Msk | PCHE_CHECON_ADRWS_Msk | PCHE_CHECON_PREFEN_Msk)))
                                      | (PCHE_CHECON_PFMWS(2) | PCHE_CHECON_PREFEN(1)));																
      //Set RF as idle mode
      RF_SetIdleMode();

• Code Inclusion inside SYS_Initialize function

• DEVICE_DeepSleepWakeSrc_T wakeSrc;
  DEVICE_GetDeepSleepWakeUpSrc(&wakeSrc);
  if (wakeSrc == DEVICE_DEEP_SLEEP_WAKE_NONE) //Initialize RTC if wake source is none(i.e power on reset)
  {
   RTC_Initialize();
  }

• 

Step 3 - heap_4.c

Comment the below mentioned original code and replace it with Modified Code inside heap_4.c (available as part of FreeRTOS-->MemMang

static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ]; --> Original Code 
 
static uint8_t  __attribute__((section (".bss.ucHeap"), noload)) ucHeap[ configTOTAL_HEAP_SIZE ]; -->Modified Code

Step 4 - Plib_rtc.h

• Replace to: #define RTC_COUNTER_CLOCK_FREQUENCY (32768U / (1UL << (0x1U - 1U)))

Note: This particular change is made to componsate the known issue earlier discussed in clock configuration. This issue wil be resolved in the upcoming release and the MCC auto generated code will have the required change by default.

Step 4 - Plib_clk.c

//check CLDO ready
    while ((CFG_REGS->CFG_MISCSTAT & CFG_MISCSTAT_CLDORDY_Msk) == 0);    
    
    //programming 4ms delay -  programming subsys_xtal_ready_delay  -> Reduce to 2ms
    //check xtal spec for delay required
    BTZBSYS_REGS->BTZBSYS_SUBSYS_CNTRL_REG1 = ((BTZBSYS_REGS->BTZBSYS_SUBSYS_CNTRL_REG1 & ~BTZBSYS_SUBSYS_CNTRL_REG1_subsys_xtal_ready_delay_Msk)
                                                | ((0x01) << BTZBSYS_SUBSYS_CNTRL_REG1_subsys_xtal_ready_delay_Pos)); 
    //wait for crystal ready
    while((BTZBSYS_REGS->BTZBSYS_SUBSYS_STATUS_REG1 & BTZBSYS_SUBSYS_STATUS_REG1_xtal_ready_out_Msk) != BTZBSYS_SUBSYS_STATUS_REG1_xtal_ready_out_Msk);

    // set PLL_enable
    BLE_REGS->BLE_DPLL_RG2 &= ~(0x02);

    //programming delay for pll lock - 500 us -> Reduce to 64us
    //32 us steps - check pll spec for final value 
    BTZBSYS_REGS->BTZBSYS_SUBSYS_CNTRL_REG3 = ((BTZBSYS_REGS->BTZBSYS_SUBSYS_CNTRL_REG3 & ~BTZBSYS_SUBSYS_CNTRL_REG3_subsys_pll_ready_delay_Msk )
                                                   | ((0x02) << BTZBSYS_SUBSYS_CNTRL_REG3_subsys_pll_ready_delay_Pos));

Step 5 - WBZ351.ld

Additional linker file related changes needs to be incorporated to define the backup RAM address. This configuration will be later make available into the MCC configuration. Until then this manual edit is required.

The highlighed code in the below image needs to be incorporated to the MCC generated WBZ351.ld file

User Application Development

Include

Enter Deep Sleep mode

• DEVICE_EnterDeepSleep(false,0);

  This API can be called to put the device to deep sleep mode.

Start Deep Sleep Advertisement

• APP_BleDsadvStart(false);

  This API can be called to start the Deep sleep Advertising.

  This API is called in the Applications initialstate - APP_STATE_INIT in app.c

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

Application use case implemention

The application implementation is purely user choice. This deep sleep advertisement application is designed in such a way that, the device enter into deep sleep upon power up and when the USR BTN 2 is pressed, the device starts deep sleep advertisement based on the fixed advertisement interval. Device wakes up from deep sleep in regular interval to do a advertisement and go back to sleep again.

This scenario is implemented by modifing default generated code inside the switch case in app.c. User can implement desired application work flow by making use of availabe function calls.