Programming PIC16F877A Using CCS C Compiler and US-Burn
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Transcript of Programming PIC16F877A Using CCS C Compiler and US-Burn
Programming PIC16F877A
Using CCS C Compiler and US-
Burn
Why Use C for Embedded Programming?
1. Portable – code can be retargeted to different processors
2. Clarity – C is easier to understand than assembly
3. Compilers produce code that is close to manually-tweaked assembly language in both code size and performance
From .c to .hex
C Compilers for Embedded Systems
� CCS C Compiler
� HI TECH Compiler
CCS vs. HI TECH
� The CCS Compiler has an extensive range of inbuilt functions
→ Save time and speed up the learning process
� The HI TECH Compiler is based towards those who are following a company policy specifying the ANSI standard with hardware functions sometimes resembling Assembler more than C
Installing CCS C Compiler IDE
� Copy CCS C directory to your hard drive
� Run pcwhupd.exe (in this directory)
� Copy the following files to installed directory
� : PCM.CRG for 16-bit PIC
� , PCH.CRG,
� PCB.CRG
� Run Patch.exe file
� Run Pcw.exe file
Installing US-Burn
1. Copy USB burn driver directory to your harddrive
2. Plug USB cable (connected to the USB port of SaigonTech PIC Board) to computer USB port
3. Turn on the power switch on the PIC board (see the next slides)
…\USB burn driver
�Click the Browse button to select the driver folder
Succefull installation
announce
�Do the steps 2 and 3 for other USB ports.
A Sample C Program:
Blinking 8 LEDs
Program Description
� Make LED’s on PORTB blink every second
Cable Wiring
� Use a 8 pin ribbon cable to connect PIC’s
jumpers B0 – B7 to LEDs’ jumpers L0 – L7
Electronic Circuit
Writing Program in PCW C
Compiler IDE
Creating a .c File
Creating a .c File
� File name: Blink8LEDs
� Choose the path
� Click Save
Editing Blink8LEDs.c
Compiling a C Program
Using US-Burn to Load a .hex
File to the PIC
� Put 16F877A in the USB Programmer socket (pay attention to the PIC direction on the socket, otherwise you will damage the PIC)
� Plug the USB cable to the PC and to the PIC board
� Turn on the power switch of PIC Board
� Run Usburn14.exe
Microcontroller Setting
Run program on the board
� Turn off the power switch on the PIC board
� Put the programmed PIC in the Run socket on the board (pay attention to the PIC direction on the socket, otherwise you will damage the PIC)
� Turn on the power switch on the PIC board to see the LEDs blink.
Summary of the
Development
Process
PIC C
PIC C
PIC C
Discussion
Look at an Alternative of BlinkLEDs.c
� Is this listing better than the previous one? Why?
One of the Most Important Skills in
Programming
� Reuse
PIC16F877A
5/6 Programming pins
8 10-bit A/D channels
2 Oscillator Inputs
2 RS-232 inputs
33 I/O ports
2 PWM channels
The PIC16F877A
� PIC: Peripheral Interface Controller
Pin Functions
� MCLR – to reset the PIC
� VDD – power supply
� VSS – ground
� OSC1, OSC2 – connect to oscillator
� The pins having the notation R can all be used as digital inputs or outputs
� The pins that are labeled as AN can be used as analog inputs
� The pins CCP1 and CCP2 are used for PWM
Exercise
1. Delete NOLVP from #fuses and rerun the program. What is the effect of this action?
2. Instead of using the PORTB, use PORTC to rewrite the example
� Try to use NOLVP and without it
Why is NOLVP Needed?
� In Single Supply Programming or Low – Voltage Programming mode (using single voltage VDD 5V to programming):
� The LVP bit will be set
� Pin B3 will have PGM function → B3 is cleared
� To make RB3 become a normal I/O pin, LVP has to be disabled
� #fuses NOLVP
Exercise
� Instead of using the PORTB, use PORTA to rewrite the example
More Details on PORTA� In the PIC16 series Port A is the analog port
connected to the analog to digital converters
� By default this port is configured as analog
⇒ You will not be able to output or input data reliably on Port A until you configure it as a digital port
Pin RA4
PIC 16F877A
Can’t work
R
VDD
How to Make RA4 Work Properly
� RA4 is made to be an open-drain output
⇒ A pull-up resistor is needed to make it work properly
Pin RA4
PIC 16F877A
Can’t work R
VDD
Pin RA4
PIC 16F877A
Open-drain output
Pull-up Resistor
References
� Microcontroller. http://www.electronics.netmyne.com/microcontroller.html
� Programming PIC Microcontrollers in BASIC. mikroElektronika © 1998 – 2004. http://www.mikroelektronika.co.yu/english/product/books/picbasicbook/00.htm#preface
� http://www.picvietnam.com/forum//showthread.php?t=357
� PICC. An introduction to programming the Microchip PIC in C. Nigel Gardner. Bluebird Electronics 1998