Objective

This example project uses the Timer System Service Library to execute functions after a specified period of time. The MPLAB^® Harmony Configurator (MHC) is used to configure the Timer System Service. Three examples of using the Timer System Service are provided:

1. One periodic delay is created to execute a callback function. This will toggle LED1 every 500 ms.
2. Another periodic delay is created to execute a different callback function. This will toggle LED2 every 1000 ms.
3. The third example shows you how to implement delays by reading the Timer System Service values directly. This will toggle LED3 every second.

The hardware for this project uses the chipKIT® Wi-FIRE board from Digilent® Inc. The three LEDs on the board are connected to PIC32 General Purpose I/O Port pins. The Ports Peripheral Library Pin toggle function is used to change the state of the LEDs.

 Materials

Hardware Tools

Tool	‍ About	‍ Purchase
chipKIT™ Wi-FIRE Development Board	‍	‍
chipKIT® PGM Programmer/Debugger	‍	‍

▶ Show Hardware Setup

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This image shows the chipKIT PGM programmer/debugger from Digilent.
Microchip programmer/debuggers (e.g. PICkit^TM 3) can also be used.

Software Tools

Exercise Files

 Procedure

The "Project and Source Files" download provides a fully functional project. It can be used as an example and requires no modifications. The following steps below provide instruction on how this project was created.

1

Create a new MPLAB Harmony project

The Target Device used on the chipKIT Wi-FIRE is the PIC32MZ2048EFG100.

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a

Install the MPLAB^® Harmony Configurator (MHC)

Before you create a new MPLAB^® Harmony project, you must install the MPLAB Harmony Configurator (MHC) graphical user interface. This GUI enables easy addition and configuration of the Harmony library files needed for your application. It also allows MPLAB X IDE to create a new MPLAB Harmony project.

Instructions for installing the MHC plugin

b

Create a New MPLAB Harmony Project

1. In the MPLAB X IDE, select File > New Project
   (or click in the toolbar).
2. Select the Microchip Embedded category if it is not already selected.
3. From the Projects list, select MPLAB Harmony Project.
4. Click Next >.

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If you do not see MPLAB Harmony Project option, you have not installed the MHC. Click here for instructions on installing the MHC plugin.

The next window should have the default Harmony Path, Project Location, and Project Path already selected for you. Remember the MPLAB Harmony framework expects to find specific files in specific locations. Do not change these default paths because the project may not build.

1. Set the Harmony installation path.
2. Set the project location.
3. Enter the project name you would like to use.
4. Change the project configuration name or just use default (optional).
5. Select the target device from the drop-down window (Which PIC32 is on my board?).
6. Click Finish.

After you click Finish, your new project will be opened.

 
MPLAB® Harmony Project Wizard Details
Learn more >

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Before creating an MPLAB Harmony Project, the MHC plugin must be installed into the MPLAB X IDE. Click here for instructions on how to install the MHC plugin.

This video will show you how to create an MPLAB Harmony Project in the MPLAB X IDE. For details on how an MPLAB Harmony Project differs from a typical standalone project, click here.

2

Use the MPLAB Harmony Configurator (MHC) to configure the PIC32 core

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a

The MPLAB^® Harmony Configurator will automatically open for you. If it doesn't, click on:
Tools ▶ Embedded ▶ MPLAB Harmony Configurator.

Click image to enlarge.

Click image to enlarge.

b

Expand the Device and Project Configuration and PIC32… Device Configuration menus to see the Device Configuration Register menus.

Expand the DEVCFG0 register menu, and change the setting as shown in this graphic.

DEVCFG0:
ICE\ICD Comm Channel Select:
ICESEL = ICS_PGx2

This option controls which pins the PIC32 uses for In-Circuit Serial Programming (ICSP) while debugging.

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This is a "don't care" for programming.

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Note how the menu is highlighted, showing a change from the default value.

Click image to enlarge.

Click image to enlarge.

3

Use MHC to configure the PIC32 clocks

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a

Click on the Clock Diagram tab.

Click image to enlarge.

Click image to enlarge

b

Verify the System Phase Locked Loop (PLL) output is configured for 200 MHz.

Verify the oscillator selection (FNOSC) is configured to use the System PLL (SPLL).

Click image to enlarge.

Click image to enlarge

 Learn More

• PIC32MZ oscillator system

4

Use MHC to configure the Timer System Service

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Click on the Options tab in the MPLAB Harmony Configurator window.

Expand the following sub-menus:

• Harmony Framework Configuration
  • System Services
    • Timer

Check the Use Timer System Service? box. You will use the default values. No other changes are needed.

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The Timer Running Frequency controls the increment rate for the System Timer counter (1000 Hz = 1 System Timer tick every 1 ms).

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The Internal Time Units (Hz) controls the decrement rate for the alarm delay period countdown timers (10,000 Hz = 10 decrements per 1 ms).

Click image to enlarge.

Click image to enlarge

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Note how the MHC configuration tree is highlighted to show a change from MHC's default value. The Timer System Service Library is a client for the Timer Driver Library. Checking the Use Timer System Service? box will also automatically check the Use Timer Driver? box (found in: Harmony Framework Configuration > Drivers > Timer) for you. This is MHC's default setting when the Timer System Service is enabled, so this change is not highlighted.

5

Use MHC to configure the I/O Port Pins

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Three PIC32 I/O Port pins will be used to blink LEDs on the board. The LED on and off time will correspond to your requested Timer System Service periods (you will create three of them).

Click on the Pin Settings tab in the MPLAB Harmony Configurator window.

The pins are listed by ascending pin number by default. To list the pins by their I/O Port names, change the pin listing order from Pins to Ports.

Scroll down the list to find the pins listed in the table below. These I/O Port pins are connected to the LEDs.

PIC32 Pin	Pin Description	Development Board Function
RG6	PORTG, Bit 6	LD1
RD4	PORTD, Bit 4	LD2
RB11	PORTB, Bit 11	LD3

Note all I/O Port pins are configured as inputs by default. To use an I/O Port pin as an output, it must be configured as such. Change the pin direction from In to Out by clicking on the button.

Also, note all pins with an analog capability are configured as analog by default. To use an I/O Port pin as a digital pin, it must be configured as such. Change the pin mode from Analog to Digital by clicking on the button.

Change settings for RG6, RD4, and RB11.

6

Use MHC to generate the code

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Click on the MPLAB^® Harmony Configurator tab, then click the Generate Code button.

Click the Save and Generate buttons on the following windows.

Click image to enlarge.

Click image to enlarge.

7

Add application states and variables to your project in app.h

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Open the app.h file, and add the APP_STATE_IDLE enumeration. After the application is initialized, it will transition to this state.

Click image to enlarge.

file: app.h

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Add the following application variables to the APP_DATA structure:

file: app.h

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9

Add application code to your project

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Open the app.c file and add the following code:

Click image to enlarge.

a

Create the callback functions that will be executed when the alarm timer periods expire.

file: app.c

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b

Add code to the APP_Initialize function to initialize the following variables:

file: app.c

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c

Add the following code to the application state machine in APP_Tasks

file: app.c

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10

Connect the development board to your computer, then select the XC32 compiler version and programmer/debugger for the project

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a

Connect your chipKIT^® Wi-FIRE and chipKIT PGM programmer/debugger (or PICkit™ 3, ICD 3 programmer/debugger) to your computer.

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The programmer/debugger shown in this image is the chipKIT PGM from Digilent^®.
Microchip programmer/debuggers (e.g. PICkit™ 3) can also be used.

b

Open the Project Properties window:
File ▶ Project Properties

Select this for the Hardware Tool (tells the IDE which programmer/debugger to use):

• Other Tools > Licensed Debugger > chipKITProgrammer

If you are using a PICkit 3 or ICD 3 programmer/debugger, choose that instead.

Select this for the compiler toolchain:

• XC32 (v1.40) If a newer compiler version is available, try using that version first.

11

Build, program and run your project

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Click the Run icon to build, program and run your project.

 Results

After successfully building your project and programming your development board, you will see three LEDs blinking.

• LED1 turns on for 500 ms, then off for 500 ms. This corresponds to the first delay period created by our application using the following line of code in app.c:

appData.sysTimerClientHandle1 = SYS_TMR_CallbackPeriodic(500, 0, APP_SysTimerCallback1);

• LED2 turns on for 1 second, then off for 1 second. This corresponds to the second delay period created by our application using the following line of code in app.c:

appData.sysTimerClientHandle2 = SYS_TMR_CallbackPeriodic(1000, 0, APP_SysTimerCallback2);

• LED3 blinks at the same rate as LED2. This System Tick counter is read every APP_Task loop to determine if one second has passed. If it has, LED3 is toggled.

 Conclusions

You have successfully used two implementations of the Timer System Service. Both create periodic delays. There are other Timer System Service implementations that allow one-shot (single) alarm delay periods.