Transcript Chapter 1 The Adventure Begins

Chapter 1
The Adventure Begins
Creating the first project and saying
“Hello to the world”
The 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!

Di Jasio - Programming 32-bit Microcontrollers in C
Preparation
The 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 Ports
Make 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

Di Jasio - Programming 32-bit Microcontrollers in C
The New Project Set Up


Launch MPLAB IDE
Follow the “New Project Set Up” Checklist to create
a new project using the Project Wizard
Di Jasio - Programming 32-bit Microcontrollers in C
The New Project Setup Checklist
1.
2.
3.
4.
5.
Select the PIC32MX360F512L device and click Next.
Select the PIC32 C-Compiler Tool Suite and click
Next
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.
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.
Click on Finish to complete the project set up
Di Jasio - Programming 32-bit Microcontrollers in C
The 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)
Di Jasio - Programming 32-bit Microcontrollers in C
The 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)
Di Jasio - Programming 32-bit Microcontrollers in C
The Editor Window

Open a new editor window by selecting

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
“File->New”, or
CTRL+N keyboard shortcut, or
by clicking on the corresponding button in MPLAB
standard toolbar.
Di Jasio - Programming 32-bit Microcontrollers in C
Creating a Source File

Type the following three lines:
/*
**
*/
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Select “File ->Save As”
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Save the file as: “Hello1.c”.
Now right click with your mouse on the
editor window to bring up the editor’s
context menu


Hello Embedded World!
Select the “Add To Project” item.
This will make the Hello1.c file the main
source file in your project
Di Jasio - Programming 32-bit Microcontrollers in C
Saving the Project


Select “Project ->Save Project”
Save the project as “Hello World.mcp”
Di Jasio - Programming 32-bit Microcontrollers in C
The 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;
};
...
Di Jasio - Programming 32-bit Microcontrollers in C
The 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
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Di Jasio - Programming 32-bit Microcontrollers in C
I/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

Di Jasio - Programming 32-bit Microcontrollers in C
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

Di Jasio - Programming 32-bit Microcontrollers in C
TRIS 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
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Di Jasio - Programming 32-bit Microcontrollers in C
The 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)
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Di Jasio - Programming 32-bit Microcontrollers in C
Compiling 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
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Di Jasio - Programming 32-bit Microcontrollers in C
Using the Simulator
Follow the SetUp Checklist
 Learn the basic debugging options offered by
the Simulator

Reset
 Single Step (Over/In)
 Animation
 Running
 Halting

Di Jasio - Programming 32-bit Microcontrollers in C
Debugging: Hello World
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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
#include <p32xxxx.h>
main()
{
// configure all PORTB pins as output
TRISB =
0;
// all PORTB as output
AD1PCFG = 0xffff;
// all PORTB as digital
PORTB =
0xff;
}
Di Jasio - Programming 32-bit Microcontrollers in C
Analog Pin Functions Multiplexing

The Analog Pins control: AD1PCFG
Di Jasio - Programming 32-bit Microcontrollers in C
Summary
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
Di Jasio - Programming 32-bit Microcontrollers in C
Advanced Material
The Disassembly Window

If you want to see what happens at the
machine instruction level:

Open the disassembly window
Di Jasio - Programming 32-bit Microcontrollers in C
The Memory Gauge
If you want to see how much memory RAM
and FLASH is being used by the project
 Open the Memory Gauge Window
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Di Jasio - Programming 32-bit Microcontrollers in C
Notes 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

Di Jasio - Programming 32-bit Microcontrollers in C
Tips 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!
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Di Jasio - Programming 32-bit Microcontrollers in C
Suggested Excercises

If you have the Explorer16 board and an in circuit debugger:


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If you have the PIC32 Starter Kit:
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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.
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.
Di Jasio - Programming 32-bit Microcontrollers in C
Recommended Readings
Kernighan, B. & Ritchie, D.
The C Programming Language
Prentice-Hall, Englewood Cliffs, NJ


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
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
Di Jasio - Programming 32-bit Microcontrollers in C
Online 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.
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Di Jasio - Programming 32-bit Microcontrollers in C