Getting Started with MPLAB® Harmony v3 Peripheral Libraries on PIC32MK GP MCUs
Contents
Objective
MPLAB® Harmony v3 is a flexible and fully integrated embedded software development framework for 32-bit microcontrollers (MCUs) and microprocessors (MPUs). MPLAB Code Configurator (MCC) includes MPLAB Harmony v3 Framework, a set of modular peripheral libraries, drivers, system services, middleware, and numerous example applications, all of which are designed to help you quickly and easily develop powerful and efficient embedded software for Microchip’s 32-bit PIC® and SAM devices.
This tutorial shows you how to use the MCC to create an application that will help you get started in developing applications on PIC32MK GP MCUs using MPLAB Harmony v3 Software Framework.
The application makes use of a PIC32MK General Purpose (GP) Development board and a MikroElectronika Weather click board (sold separately).
The application reads the current room temperature from the temperature sensor on the MikroElectronika Weather click board. The temperature reading is displayed on a serial console periodically every 500 milliseconds. The periodicity of the temperature values displayed on the serial console is changed to one second, two seconds, four seconds, and back to 500 milliseconds every time you press the switch S1 on the PIC32MK GP Development Board. Also, an LED (LED1) is toggled every time the temperature is displayed on the serial console.
The application you create will utilize:
- The Serial Peripheral Interface (SPI) Peripheral Library (PLIB) reads the temperature from a temperature sensor.
- The TMR2 PLIB periodically samples temperature sensor data.
- The CORE TIMER PLIB uses a blocking timer delay for initializing the temperature sensor.
- The Universal Asynchronous Receiver Transmitter (UART) and Direct Memory Access (DMA) PLIBs to print the temperature values on a COM (serial) port terminal application running on a PC.
- The General Purpose Input/Output (GPIO) PLIB changes the periodicity of temperature sensor data readings using the SWITCH press event and toggles the LED.
In the process, the lab will also demonstrate the use of callback functions.
Two ways to use this tutorial
- Create the project from scratch:
- Use the provided source files and step-by-step instructions below.
- Use the solution project as an example:
- Build the solution project and program it to the PIC32MK GP Development Board to observe the expected behavior.
Lab Objectives
Create an MPLAB X IDE Harmony v3 project for a PIC32MK GP microcontroller from scratch.
- Use the MCC to configure and generate Harmony v3 PLIBs code for TMR2, SPI, UART, CORE TIMER, DMA, and GPIO peripherals.
- Use the Harmony v3 PLIB Application Programming Interfaces (APIs) to implement the application.
Materials
Hardware Tools
Figure 1: Hardware Setup
Figure 2: Hardware Modification
Software Tools
For this lab, download the following repositories from GitHub:
- CSP: The following table shows the summary of contents.
| Folder | Description |
|---|---|
| apps | Example applications for CSP library components |
| arch | Initialization and starter code templates and data |
| docs | CSP library help documentation |
| peripheral | PLIB templates and configuration data |
- DEV_PACKS: The following table shows the summary of contents.
| Folder | Description |
|---|---|
| Microchip | Peripheral register specific definitions |
| arm | Core specific register definitons (CMSIS) |
- Use the MPLAB Code Configurator Content Manager (MCC) to download the repositories.
Overview
This lab shows you how to create an MPLAB Harmony v3 project from scratch, configure, and generate Harmony v3 PLIB code for TMR2, SPI, UART, CORE TIMER, DMA, and GPIO peripherals. It demonstrates the reading of temperature sensor values from the temperature sensor available on the MikroElectronika Weather click board periodically and displays it on a serial console. The periodicity of temperature sampling is changed on every switch press event. Every time the temperature is displayed on the serial console, an LED is toggled.
Application Flow Sequence
The application initializes clock, PORTs and other peripherals (configured through the MCC) by calling the function SYS_Initialize.
The application registers callback event handlers for SERCOM (as I²C), DMA, RTC, and External Interrupt Controller (EIC) Peripheral Libraries. The callback event handlers are called back by the peripheral libraries when the transaction completion events occur.
Note:
- A callback event handler for SERCOM (as USART) is not registered as the actual USART data transfer, and is accomplished by the DMA. The DMA calls back the callback event handler when the DMA transfer request is completed.
- RTC peripheral is used for implementing the time period instead of the timer peripheral. This is done to demonstrate how to configure and use RTC peripheral in an application (particularly low power application).
The application checks whether the configured RTC timer period has expired. On every timer period expiration, the application calls the function SERCOM3_I2C_WriteRead to submit a temperature sensor read request to the I²C PLIB. The I²C PLIB calls back the registered callback event handler when the latest temperature value is read from the sensor. The application sets a flag in the RTC callback event handler.
Figure 3: shows the flow sequence of the application task
The application checks the temperature read complete flag to submit a write request to DMA to print the latest temperature value (in a formatted message) onto the serial console over the UART interface.
The application also monitors the pressing of the switch S1. If a switch press is detected, the application changes the temperature sampling rate from the default 500 milliseconds to one second. On subsequent switch press, the application changes the temperature sampling rate to two seconds, four seconds, and back to 500 milliseconds. The application cycles the temperature sampling rate on every switch press, as shown in the figure below.
Figure 4: Pressing of the switch S1
The application also toggles user LED LED1 every time the latest temperature value is displayed on the serial console.
Lab Source Files and Solutions
This ZIP file contains the completed solution project for this lab. It also contains the source files needed to perform the lab as per the following step-by-step instructions (see the "Procedure" section on this page).
ZIP
Extracting the ZIP file creates the following folders:
- pic32mk_getting_started contains the lab solution (in the firmware folder) and source files (in the dev_files folder).
- dev_files contains the subfolder pic32mk_gp_db which contains the application source files and other support files (if any) required to perform the lab (see "Procedure" section below).
- firmware contains the completed lab solution project. It can be directly built and programmed on the hardware to observe expected behavior.
Procedure
Lab Index
Step 1: Create project and configure the PIC32MKGP
- Step 1.1 - Create MPLAB Harmony v3 Project Using MPLAB X IDE
- Step 1.3 - Verify Clock Settings
Step 2: Configure SPI, UART, CORE TIMER, and TMR2 Peripheral Libraries
- Step 2.1 - Configure TMR2 Peripheral Library
- Step 2.1 - Configure CORE TIMER Peripheral Library
- Step 2.2 - Configure SPI Peripheral Library and SPI Pins
- Step 2.3 - Configure UART Peripheral Library and UART Pins
- Step 2.4 - Configure DMA Peripheral Library
Step 3: Configure Pins for Switch and LED
- Step 3.1 - Configure Switch Button Pin with GPIO to Generate an Interrupt
- Step 3.2 - Configure LED Pin
- Step 3.3 - Rename the Default Main File
Step 4: Generate Code
Step 5: Add Application Code to the Project
Step 6: Build, Program, and Observe the Outputs