Difference between revisions of "PIC Microcontrollers with C18 Compiler"
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==PIC Microcontroller== |
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The microcontroller used for this project is the PIC18F4431 made by [http://www.microchip.com Microchip]. This is an 8-bit microcontroller with motor PWM generators, a quadrature encoder interface (QEI), and other "peripherals". The microcontroller uses an external 40MHz oscillator. |
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The microcontroller controls two wheel motors with PWM driving external H-bridges. The H-bridges draw their power directly from the batteries, not regulated power. |
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==Compiler and IDE== |
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Each of the wheels also has a quadrature encoder. The left wheel encoder is connected to the PIC's QEI via a schmitt trigger buffer. The right wheel encoder is wired to a U.S. Digital LS7183 chip (because the PIC only has 1 QEI) which outputs pulses on one of two pins, depending on whether the wheel is spinning backwards or forwards. The two pins are then each connected to a counter on the PIC, which keeps track of the number of pulses. The location of the wheel can be determined by subtracting the reverse-pulse counter from the forward-pulse counter. |
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The C18 compiler is a C-language compiler for the Microchip PIC18 family of microcontrollers. The student version of this compiler is available for free at Microchip's website. The difference between the student version and the commercial version is the level of optimization available. For most purposes, the student version should suffice. |
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Be aware that there are some differences between Microchip's C18 compiler and C compilers for other platforms. For example, an <tt>int</tt> data type in C18 is 16 bits, instead of the usual 32 bits. Refer to the C18 user guide for more information. |
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The PIC is interfaced with the XBee modem via the RS-232 serial interface. |
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Microchip's IDE, MPLAB, is also available for free at Microchip's website. |
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===Programming the PIC=== |
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====Setting Up==== |
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For this project, Microchip's free MPLAB IDE and free C compiler were used to program the PIC18F4431. '''If you are using the ICD2 programmer, be sure to follow the installation instructions carefully, or Windows may attempt to install the wrong drivers.''' After installing both MPLAB and C18, create a new project with the project wizard. Follow the prompts, and you should end up with an empty project if you did not add any existing files. |
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==Connecting the Programmer== |
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We must now add a linker script to your project. Make sure '''View>Project''' is checked, then right-click on '''Linker Scripts''' in the project panel and click on '''Add Files...'''. The linker scripts are in folder '''MCC18\lkr'''. Find the file that corresponds to your microcontroller (p18f4431 (or p18f4431i if you are using the ICD2 programmer) for the PIC18F4431 microcontroller). |
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[[media:Using_ICD2_Poster.pdf|Connecting the ICD2 Programmer]] |
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==Writing the Code== |
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We now add source and header files in the same manner. To make a new source or header file, go to '''File>New''', and then save the file as a <tt>.c</tt> or <tt>.h</tt> file. With the default settings, all the source and header files that you write must be in the same folder or MPLAB will give you an error message stating that it cannot find the files. You can change the environment variables by going to '''Project>Build Options...>Project. |
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[[Writing Code with the C18 Compiler]] |
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==Example Projects== |
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[[PIC Analog-Digital-Converter Example]] |
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In your main source file, which we will call <tt>main.c</tt>. At the top, you should include the line |
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<pre> |
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#include <p18f4431.h> |
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</pre> |
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This header file contains the definitions and names of the Special Function Registers (e.g. PORTA, TRISA, etc). This file should already be in the default path for header files (the '''MCC18/h''' folder). Any header files that you write yourself will need to be added to the project. |
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[[PIC Motor Control and Serial Port Example]] |
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====Recommended Reading==== |
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[[PIC Motor Control with EEPROM and Interactive Menu Example]] |
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*If MPLAB has trouble connecting with the ICD2, open the Device Manager ('''Control panel>System>Hardware>Device Manager''') and disable then re-enable the ICD2. Also be sure that you followed in installation instructions in the manual when you installed the ICD2. |
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For more examples, see the C18 User's Guide and the application notes on Microchip's website. |
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[[PIC/C18 Compiler Tips and Troubleshooting]] |
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==XBee== |
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==Code== |
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==PCB== |
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==Documents== |
==Documents== |
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===MPLAB and C18 Compiler=== |
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[[media:MPLAB_GS.pdf | MPLAB Quick Start Guide]] |
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[[media:MPLAB_UG.pdf | MPLAB User's Guide]] |
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[[media:Microchip_C18_GS.pdf | C18 Compiler Getting Started]] |
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[[media:Microchip_C18_UG.pdf | C18 Compiler User's Guide]] |
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[[media:Microchip_C18_libraries.pdf | C18 Compiler Libraries]] |
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===PIC18F4431=== |
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[[media:PIC18F4431_datasheet.pdf | PIC18F4431 Datasheet]] |
[[media:PIC18F4431_datasheet.pdf | PIC18F4431 Datasheet]] |
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[[media:PIC18F4431_errata.pdf | PIC18F4431 Errata]] |
[[media:PIC18F4431_errata.pdf | PIC18F4431 Errata]] |
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Latest revision as of 15:23, 11 October 2007
Compiler and IDE
The C18 compiler is a C-language compiler for the Microchip PIC18 family of microcontrollers. The student version of this compiler is available for free at Microchip's website. The difference between the student version and the commercial version is the level of optimization available. For most purposes, the student version should suffice.
Be aware that there are some differences between Microchip's C18 compiler and C compilers for other platforms. For example, an int data type in C18 is 16 bits, instead of the usual 32 bits. Refer to the C18 user guide for more information.
Microchip's IDE, MPLAB, is also available for free at Microchip's website.
Connecting the Programmer
Connecting the ICD2 Programmer
Writing the Code
Writing Code with the C18 Compiler
Example Projects
PIC Analog-Digital-Converter Example
PIC Motor Control and Serial Port Example
PIC Motor Control with EEPROM and Interactive Menu Example
For more examples, see the C18 User's Guide and the application notes on Microchip's website.
Tips and Troubleshooting
PIC/C18 Compiler Tips and Troubleshooting
Documents
MPLAB and C18 Compiler
PIC18
PIC18 Configuration Settings Addendum
