Chapter 1 The Adventure Begins

1. Chapter 1 The Adventure Begins Creating the first project and saying “Hello to the world”

2. 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!

3. 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

4. The New Project Set Up • Launch MPLAB IDE • Follow the “New Project Set Up” Checklist to create a new project using the Project Wizard

5. The New Project Setup Checklist • 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

6. 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)

7. 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)

8. The 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.

9. Creating 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

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

11. 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; }; ...

12. 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

13. 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

14. 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

15. 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

16. 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)

17. 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

18. Using the Simulator • Follow the SetUp Checklist • Learn the basic debugging options offered by the Simulator • Reset • Single Step (Over/In) • Animation • Running • Halting

19. Debugging: 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

20. Analog Pin Functions Multiplexing • The Analog Pins control: AD1PCFG

21. 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

22. Advanced Material

23. The Disassembly Window • If you want to see what happens at the machine instruction level: • Open the disassembly window

24. 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

25. 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

26. 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!

27. Suggested 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.

28. Recommended Readings Kernighan, B. & Ritchie, D. The C Programming Language Prentice-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

29. 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.