Download Práctica de Informática Industrial. Programación de

Práctica de Informática Industrial.
Programación de Microcontroladores en C.
El objetivo de esta práctica es practicar los conocimientos adquiridos en las clases de teoría sobre
programación en C.
Las instrucciones necesarias para la instalación y configuración del compilador (ya realizadas) se
encuentran en el apéndice 1 (en inglés). En este mismo apéndice también encontramos la
información necesaria para el uso del entorno de depuración ICD de microchip.
En el apéndice 2 (en inglés) encontramos la descripción y el esquema de la placa de evaluación
del 16F877 empleada.
Es fundamental disponer además de la documentación entregada sobre el compilador HT-PICC lite
y sobre el 16F87X.
Se pide:
1. Realizar un programa que encienda todos los LEDs cuando se actiba el pulsador.
2. Realizar un programa que encienda y apague el LED0 (sin emplear interrupciones) con
una frecuencia de 10Hz (modificar el incluido en el apéndice1).
3. Igual pero empleando el Timer 1 para generar interrupciones.
4. Realizar un programa que lea con una periodicidad de 10Hz el valor de tensión generado
por el potenciómetro y lo represente en los LEDs.
Una vez realizado el apartado 5 debe grabarse el programa en el 16f877 de forma que se ejecute
sin tener que conectar la placa de evaluación al ICD. Para ello deben buscarse las opciones
adecuadas del compilador y del ICD.
El desarrollo de la práctica y sus resultados debe resumirse en una memoria a entregar por cada
grupo de prácticas dentro de los 15 días posteriores al desarrollo de la misma.
Apendix1:
MPLab and Hi-Tech C Tutorial
The following tutorial covers PIC micros, MPLab and Hi-Tech C.
•
•
•
•
•
how to install MPLab
how to install Hi-Tech C
how to set up a project for Hi-Tech C under MPLab. Note: Other methods do not support
libraries, additional C files, or incremental compiles.
how to use the simulator
how to use the MPLAB-ICD emulator
Getting to know the MPLab and Hi-Tech C environment
Installing MPLab
First off, you will need the development program for PIC micros, MPLab. The latest version of
MPLab at the time of writing is 5.70. If you go to the Microchip web site http://www.microchip.com/
you will find the latest version of this software. A screenshot of the Integrated Development
Environment (IDE) is shown below.
Installing a C compiler
MPLab comes with it's own assembler. However, with the power of microprocessors these days, a
C compiler is the preferred choice. Programming in C is not only easier and more powerful, code is
also portable to other microprocessors such as Atmel, TI, or Zylog. In this tutorial will be using the
officially supported Microchip C compiler, Hi-Tech C. This is available from http://www.htsoft.com/.
The latest version at the time of writing is 7.86pl3. It is recommended that earlier versions are not
used. In my two years of experience with Hi-Tech C, I have found it to be an excellent product.
There has never been any case where the compiler has been at fault - I believe that the latest
version is bug free.
Telling MPLab where to find the Hi-Tech C compiler
1. After you have installed Hi-Tech C, you have to tell MPLab where to find the C compiler.
2. In MPLab, select menu ‘Project’ then ‘Install Language Tool’. You should see the dialogue box
as shown below.
3. Change the language suite to ‘Hi-Tech’, and the tool name to ‘PIC-C compiler’, as below.
4. Browse to the Hi-Tech C directory ‘C:\HT-PIC\BIN\’ and find the executable PICC.EXE as
shown in the screenshot below.
5. Change the tool name to ‘PIC-C linker’ and repeat the process, as shown in the screenshot
below..
Note: Both Linker and Compiler must be specified. Both Linker and Compiler point to PICC.EXE.
Trial Version: for the trial version of Hi-Tech C, point both the Linker and Compiler to PICL.EXE
Creating your first project for Hi-Tech C
This particular tutorial is for the 12X, 16X and 17X version of Hi-Tech C (piccdemo.exe or the retail
version). It does not support the 18X version of Hi-Tech C (picc18demo.exe or the retail verison).
There is a FAQ on http://www.htsoft.com/showing how to integrate the 18X compiler with MPLab.
Note: It is recommended that this method is used. Its not important at the moment, as the tutorial
will teach the correct method, but selecting 'PIC C Compiler under 'node properties' for
'project[.hex]' makes it impossible to have multiple files, object files or libraries.
If you follow these steps exactly, you will get a working project.
1. From the MPLab IDE, select the menu option ‘Project’ then ‘New Project’. Go into Explorer, and
create a directory for your project on the hard drive. Back in MPLab, browse to this directory.
2. In MPLab, type in the project file name, ‘project.pjt’ then click ‘Ok’. This brings up the edit
project window as shown below.
3. Select development mode to be ‘MPLab-SIM, 16F877’ as below. Ignore the warning that 'No
hex file has been built for this project'.
4. Select language tool suite to be ‘Hi-Tech’ as below. Ignore the warning that 'You will lose all
command line options'.
5. Click on ‘project [.hex]’ then ‘node properties’ as above.
6. You will see a window. Change 'Language Tool' to PIC C Linker, then match the options to the
screen shot below.
7. Note the 'Compile for MPLAB-ICD' option switch below. This reserves 256 program words at
the top of memory and various ram bytes, to make the .hex file compatible with the MPLAB-ICD
emulator. The 'Compile for MPLAB-ICD' option is not needed with the ICEPIC 2000 emulator.
8. Note the ‘-fakelocal’ switch in ‘additional command line options' below. This allows one to view
local variables inside a function.
9. Click ‘OK’, twice, to the back into the MPLab IDE. Click ‘File’ then ‘New File’. Save it as
‘project.c’, in your own directory, as shown below. Now there should be two files in this directory project.pjt and project.c.
10. Go back into the "edit project" dialogue by selecting menu ‘Project’ then ‘Edit Project’.
11. Click on ‘add node’ then add ‘project.c’ as shown below:
12. Click on project[.c] then "node properties". Change the options to match the picture below. All
other options are unchanged from the defaults.
13. Click ‘Ok’, twice, to go back into editing the project.c file.
14. Well, we are almost there. Type a short skeleton program to satisfy the compiler:
#include <pic.h>
main()
{
}
15. Select menu ‘Project’ and 'Make Project (F10)’ to compile everything. You should see the
results displayed, as in the screenshot below.
16. If you have any errors at all, such as 'MPLab cannot find .hex file' or 'Build tool not installed
properly', check that the language tools are installed properly. See here.
17. Later on, if you have more files, libraries or object files, you can add them to the project by
clicking on 'add node'. These files will be compiled individually, then linked at the end.
18. If you want incremental compiles, add the line 'c:\ht-pic\include' under 'include path' in the 'edit
project' dialogue.
19. Finished. The sample project created with these instructions is available for download.
20. If you didnt get a working project, follow through it again, copying the instructions exactly,
paying particular care to the screenshots. If you still cant get it working email
mailto:[email protected]?subject=Project setup issues.
Using the simulator to test code
MPLab has a built in microprocessor simulator. If you compile C or assembly code you can test its
operation by simulating what it does. Select menu ‘options’ then ‘development mode’. Set the
development mode to ‘MPLAB-SIM simulator’ See menu ‘Debug’ and ‘Run’ for running, stopping,
single stepping, and reset commands. Set breakpoints by right clicking on a line of C, and selecting
‘breakpoint’. The stopwatch under ‘window’ and ‘stopwatch’ is useful for timing how long code takes
to run – set breakpoints before and after then run it.
Using an In Circuit Debugger (ICD)
Normally, when you construct a device using a microprocessor, you plug the microprocessor into
the socket on the PCB and it works. An ‘In Circuit Debugger’ (ICD) plugs into the socket instead of
the microprocessor, under the control of a computer.
The advantage of an emulator over a stand-alone microprocessor is that you can see what's going
on inside the chip. You can single step through lines of code, set breakpoints, view variables, and
time how long sections of code take to execute. Its operation is exactly the same as using the
simulator.
The difference between an emulator and a simulator is that a simulator is just a program running on
the computer. An emulator plugs into the target circuit, and can interact with the real world such as
memory chips, button presses, and variable voltages.
Using the MPLAB-ICD emulator
In this tutorial, we will be using the MPLAB-ICD emulator. Read through the documentation for the
MPLAB-ICD emulator, to get a basic idea of how it works. This is available in the MPLab IDE,
under ‘Help’ then ‘MPLAB-ICD help’
Next, set up the emulator.
1. Connect the emulator to COM1 of the computer with a serial cable.
2. The emulator probe is like any microprocessor -- its needs power, the reset pin pulled high, and
a clock.
3. Plug the 28-pin or 40-pin emulator probe into the development board, making sure that it is
plugged in the correct way around.
4. Give the development board power by connecting in the 9V plug pack. The red LED should be
flashing on the emulator probe, indicating that is ready to the reset.
5. Start up MPLab. Load up the project, as before. Select the menu option ‘Options’ then
‘Development Mode’. Select the options to match the dialogue box, as shown below.
6. Click ‘Reset’ and if the emulator is connected properly to the computer, you should see the
diaglogue box as shown below. Change the options so that it matches the control box below.
7. These settings are the default for almost every situation, with the exception of the
oscillator. When using an external crystal with speeds of higher than 8Mhz use the settings as
shown above. Crystal speeds of lower than 8MHz use ‘XT’ for the oscillator setting instead ‘HS’.
When using a RC oscillator for the clock, made up of a resistor and a capacitor, use ‘RC’ for the
oscillator setting instead of ‘HS’.
8. Next, to test if the emulator is working, type in the sample program shown below or download
the project then unzip it into ‘c:\pic\’:
//sample program for MPLAB-ICD development board
//set oscillator to ’RC’ for 2Mhz, then check to see if all red LEDs
flash @ 2Hz
#include <pic.h>
main()
{
unsigned int i;
TRISC=0b00000000;
o=output, 1=input
while(1)
{
PORTC=0xFF;
for(i=0;i<28000;i++) {};
gives ~500ms
PORTC=0x00;
for(i=0;i<28000;i++) {};
gives ~500ms
}
}
//set ports of port C to output //loop forever
//turn leds on, 0xFF = 0b11111111
//delay, its 9 clock ticks per i++, @2Mhz
//turn leds off, 0x00 = 0b00000000
//delay, its 9 clock ticks per i++, @2Mhz
9. Compile the program by selecting menu option ‘Project’ then ‘Make Project’. Or you can press
F10.
10. Download the program into the flash chip of the emulator by clicking ‘Program’ in the white
MPLAB-ICD control box as shown above.
11. When it is finished, run the program by selecting menu option ‘Debug’ then ’Run’ then ‘Run’. Or
you can press F9.
12. You should see the 8 red lights on the development board flashing at 1Hz.
13. Finish.
We welcome any suggesions or comments! Send them to Shane Tolmie on
mailto:[email protected].
This site is a completely separate site to www.microchip.com, and is maintained independently of
Microchip Ltd., manufacturers of the PIC micro.
All code on this site is free for non-commercial use. Commercial use normally free, however, it is
prohibited without contacting DesignREM Ltd. for permission.
All content on this site created by Shane Tolmie is copyrighted by Shane Tolmie 2000, 2001, 2002,
2003.
Apendix2: MPLAB ICD Demo Board
The MPLAB ICD Demo Board is a simple demonstration board that supports
PIC16F87X microcontrollers. The board can be used stand-alone with a preprogrammed
part or with the MPLAB ICD Module and MPLAB ICD Header. A
sample program is provided to demonstrate the unique features of the
devices. Although a 40-pin and a 28-pin socket are provided to accommodate
the different packages, only one processor can be run at a time.
Processor Sockets
Available sockets are:
• 40-pin socket for PIC16F871/874/877
• 28-pin socket for PIC16F870/872/873/876
Additional 20- and 14-pin male to male headers have been provided as standoffs.
Simply insert the desired headers onto the MPLAB ICD Demo Board and
then plug the MPLAB ICD Header into the stand-offs. Without the stand-offs,
the MPLAB ICD Header would not plug into the sockets. Or, simply insert the
device directly onto the MPLAB ICD Demo Board.
Display
Eight red LEDs are connected to PORTC of each processor type. The
PORTC pins are set high to light the LEDs.
DIP Switches
Eight DIP Switches are provided in a package as SW3. When all switches are
in the ON position, each of eight red LEDs is connected to a pin of PORTC.
Power Supply
The MPLAB ICD Demo Board uses a 9.0V power supply to create a 5.0V VDD
voltage to power the MPLAB ICD Module. This 9V power supply is NOT
provided with the MPLAB ICD system. If you own a PICSTART Plus
Programmer, you can use its power supply to power the MPLAB ICD Demo
Board. The part number is AC162039. The minimum power supply
specifications for the MPLAB ICD Demo Board as shipped are:
• DC power supply: 9VDC @ 0.3A
• With barrel connector: ID = 2.5 mm, OD = 5.5 mm, Barrel length:
10.0 mm, Inside positive
ICD Connection
A modular cable connection next to the power supply can be used to connect
the MPLAB ICD Demo Board directly to the MPLAB ICD Module.
_ 2000 Microchip Technology Inc. DS51184D-page 69
RS-232 Serial Port
A RS-232 level shifting circuit has been provided to support connection to a
RS-232 host through the DB9 connector. The port is configured as DCE, and
can be connected to a PC using a straight through cable, as opposed to a null
modem cable. The circuitry must be populated by the user:
• U4 – Analog Devices MAX233A or equivalent
• R14-R19 – 330&, 1/8Wresistor
• C7-C11 – 0.1 µF capacitors
• J4 – DB9 female right angle connector
Push-Button Switches
Two push buttons provide the following functions:
• MCLR to reset the processor
• Active low switch connected to RB0
Oscillator Options
You can use the on-board RC oscillator circuit or plug an oscillator in the 4-pin
socket. Make sure to set the jumper (JP1) to the proper selection.
• Socket provided for clock oscillator – use an oscillator from 32 kHz to
20 Mhz
• RC circuit – the frequency generated by the R3 resistor and C4 capacitor
ranges from about 3.5 Mhz to 6 Mhz, depending on the operating
voltage and ambient temperature.
Analog Input
A 1Kohm potentiometer is connected through a series 470 ohm resistor (to
protect the part should the pin be configured as an output) to RA0/AN0. The
port can be adjusted from VDD to GND to provide an analog input to the
PIC16F87X parts.
.