Chapter 1 The Adventure Begins

Chapter 1Chapter 1 The Adventure Begins The Adventure Begins

Creating the first project and saying “Hello to the world”

Di Jasio - Programming 32-bit Microcontrollers in C

The PlanThe Plan The first project with MPLAB IDE

The project window The editor The output window

A first statement A first complete program

Controlling I/Os: Ports and Pins Building the project Using the MPLAB SIM simulator The first debugging experience Hello World!


PreparationPreparationThe following tools will be used in this lesson: MPLAB IDE, Integrated Development Environment (v8.00 or later,

free) MPLAB SIM, free software simulator

(included in MPLAB installation) MPLAB C32, C compiler

(free Student Edition)The following pieces of documentation will be used during this lesson: PIC32MX Datasheet –DS61143 (latest rev.) PIC32MX Family Reference Manual – DS61120

Section 12. I/O PortsMake sure they are available and/or installed and ready to use on your

computer.You can download them from Microchip web site at:

http://www.microchip.com/mplab And

http://www.microchip.com/c32

http://www.microchip.com/mplab

http://www.microchip.com/c32


The New Project Set UpThe New Project Set Up Launch MPLAB IDE Follow the “New Project Set Up” Checklist to create

a new project using the Project Wizard


The New Project Setup ChecklistThe New Project Setup Checklist

1. Select the PIC32MX360F512L device and click Next.

2. Select the PIC32 C-Compiler Tool Suite and click Next

3. Click the Browse button and create a new folder. Name the new folder “Hello”, and inside it create the project file “Hello World”, then click Next.

4. Click Next to proceed to the following dialog box since there is no need to copy any source files from any previous projects or directories.

5. Click on Finish to complete the project set up


The Project WindowThe Project Window If not automatically visible, open the Project

Window: Select “View-> Project” from the main menu

Note: The project window can be made “dockable” so that it will stick to one of the edges of the screen (left)


The Output WindowThe Output Window If not automatically visible, open the Output

Window: Select “View-> Output” from the main menu

Note: The output window can be made “dockable” so that it will stick to one of the edges of the screen (bottom)


The Editor WindowThe Editor Window Open a new editor window by selecting

“File->New”, or CTRL+N keyboard shortcut, or by clicking on the corresponding button in MPLAB

standard toolbar.


Creating a Source FileCreating a Source File Type the following three lines:

/*** Hello Embedded World! */

Select “File ->Save As” Save the file as: “Hello1.c”.

Now right click with your mouse on the editor window to bring up the editor’s context menu

Select the “Add To Project” item.

This will make the Hello1.c file the main source file in your project


Saving the ProjectSaving the Project Select “Project ->Save Project” Save the project as “Hello World.mcp”


The First Statement: #includeThe First Statement: #include Add a first C statement:

#include <p32xxxx.h>

Which will actually include a file called “p32mx360f512l.h” whose content looks like:

...extern volatile unsigned int WDTCON __attribute__((section("sfrs")));typedef union { struct { unsigned WDTCLR:1; unsigned WDTWEN:1; unsigned SWDTPS0:1; unsigned SWDTPS1:1; unsigned SWDTPS2:1; unsigned SWDTPS3:1; unsigned SWDTPS4:1; unsigned :7; unsigned FRZ:1; unsigned ON:1; };...


The main() functionThe main() function Add the following lines of code:

main() {

…}

There can be only one main() function The curly {} brakets When is it executed What happens after it is executed


I/O PINSI/O PINS

I/O pins can be configured as: Digital Inputs Digital Ouputs (Push Pull) Digital Outputs (Open

Drain) Analog Inputs Dedicated inputs or

outputs for a number of peripherals


PORTA and PORTB PORTA and PORTB Different PORTs group pins with different

functions PORTB for example contains a number of

pins that can be configured as analog inputs to the Analog to Digital Converter (ADC) .

PORTA contains a number of pins that can be used for the JTAG interface, TRACE function, and the I2C interface

Refer to the specific device datasheet for a detailed list of each PORT/pin capabilities


TRIS registersTRIS registers TRIS registers control the direction of each

pin (Input/Output) TRISA, TRISB… each port has a

corresponding tris register Setting a bit to 1 configures a pin as Input Clearing a bit to 0 configure the corresponding pin as

an output


The Watch WindowThe Watch Window

Once a debugging tool (MPLAB SIM) is selected

Open the Watch Window To inspect the content of a variable (symbol) or any

of the special function registers (SFR) Select the desired output format(s)


Compiling and LinkingCompiling and Linking A compiler transforms the C source code (.c)

and all inlcuded (.h) files into a relocatable code object (.o)

The linker takes all the relocatable code objects (.o) and libraries (.lib) and assembles them into an executable (.hex) file


Using the SimulatorUsing the Simulator Follow the SetUp Checklist Learn the basic debugging options offered by

the Simulator Reset Single Step (Over/In) Animation Running Halting


Debugging: Hello WorldDebugging: Hello World

#include <p32xxxx.h>main(){ // configure all PORTB pins as output TRISB = 0; // all PORTB as output AD1PCFG = 0xffff; // all PORTB as digital PORTB = 0xff;}

Set all pins of PORTA as outputs and then turn them on Notice how the JTAG port takes precedence unless disabled Now Try using PORTB Notice how by default the pins are configured as analog inputs

and always read as 0 unleas re-configured


Analog Pin Functions MultiplexingAnalog Pin Functions Multiplexing

The Analog Pins control: AD1PCFG


SummarySummary

In this lesson we learned: How to create a new project How to create our first C source file How to build a project using the MPLAB C32

compiler About PINs and PORTs How to configure and control simple digital

output pins How to configure and use the MPLAB SIM

simulator

Advanced MaterialAdvanced Material


The Disassembly WindowThe Disassembly Window If you want to see what happens at the

machine instruction level: Open the disassembly window


The Memory GaugeThe Memory Gauge If you want to see how much memory RAM

and FLASH is being used by the project Open the Memory Gauge Window


Notes for the PIC MCU ExpertsNotes for the PIC MCU Experts The PIC32 PORTS are not necessarily 32-bit

large. In fact most PORTS are 16-bit at the most.

The PIC32 PORTS are designed to be compatible with the 8-bit and 16-bit PIC PORTS

I/O PORT control in C is easy Use the LATx registers to control directly the

output latches


Tips and TricksTips and Tricks Interfacing to 5V input and output signals is

possible with some caution: Digital Input pins are 5V tolerant Digital Output pins can be configured as Open Drain Use the ODCx registers to configure an output pin for

Open Drain mode. Watch Out! Pins that are multiplexed with analog

functions are NOT 5V tolerant!


Suggested ExcercisesSuggested Excercises If you have the Explorer16 board and an in circuit debugger:

Use the MPLAB REAL ICE Debugging or the MPLAB ICD2 Debugging checklists to help you prepare the project for debugging.

Insert the instructions required to disable the JTAG port. Test the PortA example, connecting the Explorer16 board and checking

the visual output on LED0-7. If you have the PIC32 Starter Kit:

Use the PIC32 Starter Kit Debugging checklist to help you prepare the project for debugging.

Modify the code to operate on PortD, but do NOT disable the JTAG port. Test the code by checking the visual output on LED0-2 on the PIC32

Starter Kit itself. In both cases you can:

Test the PortB example by connecting a voltmeter (or DMM) to pin RB0, if you can identify it on your board, and watching the needle move, between 0 and 3.3V, as you single step through the code.


Recommended ReadingsRecommended ReadingsKernighan, B. & Ritchie, D.The C Programming LanguagePrentice-Hall, Englewood Cliffs, NJ

When you read or hear a programmer talk about the “K&R” … they mean this book!

Also known as “the white book”, the C language has evolved quite a bit since the first edition was published in 1978!

The second edition (1988) includes the more recent ANSI C standard definitions of the language

The MPLAB C32 compiler adheres to the ISO/IEC 9899:1990 (also known as C90) standard


Online ResourcesOnline Resources http://en.wikibooks.org/wiki/C_Programming This is a Wiki-book on C programming and as

such it is a bit of a work in progress. It’s convenient if you don’t mind doing all your reading online.

Hint: look for the chapter called “A taste of C” to find the omnipresent “Hello World!” example.

Documents

Chapter 1 The Adventure Begins