saxion university of applied sciences advanced microcontrollers a practical approach

Saxion University of Applied Sciences

Advanced MicrocontrollersA practical approach

Microcontroller programming

2

Goals Responsibilities

Topics

MicrocontrollersA practical approach


3

Goals Some more advanced

knowledge of microcontrollers

Reading and using data-sheets

Building, programming and documenting a little microcontroller system.


4

Responsibilities

The student is responsible for the hard-en software, there are more groups who must use it

Defects must be reported immediately


5

Topics PIC family Architecture PIC18F2580 Interrupts Serial communication LCD Assembly A very little microcontroller



6

Topics PIC family Architecture PIC18F2580 Interrupts Serial communication LCD Assembly A very little microcontroller



7

PIC18F2580 Device


8

PIC18F2580 pinout


9

Block diagram


10

Programming

Header Functions

Initialisation…

Main program1. Initialisation (function call)2. Program with function calls in

infinite loop


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// Project name// Author// Date of creation// Revision number

#include <p18f2580.h>

#define off 0#define on1

Program header


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Initialisation function Digital pin configuration

void init(void) {PORTB = 0; // All OFFTRISA = 0b11111111; // All inputsTRISC = 0b11111111; // All inputsTRISB = 0b00111111; // RB6, RB7 output

}


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Write Output function

void LED2(char in) {PORTBbits.RB6 = in; // LED2 = in

}


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Main Program

void main(void) {init(); // initialisation

while(1) { // infinite loopif (PORTAbits.RA4 == 1) LED2(ON);else

LED2(OFF);}

}


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Interruptssources • External Interrupt RA2/INT • TMR0 Overflow Interrupt • PORTA Change Interrupts • 2 Comparator Interrupts • A/D Interrupt • Timer1 Overflow Interrupt • Timer2 Match Interrupt • EEPROM Data Write Interrupt • Fail-Safe Clock Monitor Interrupt • Enhanced CCP Interrupt


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Interrupts(chapter 10 datasheet)sources


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Timer 0

• 8-bit/16-bit timer/counter

• Readable and writeable

• 3-bit software programmable prescaler (2-4-8-…-256)

• Internal or external clock select

• Edge select for external clock

• Interrupt on overflow from 0xFF to 0x00


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Timer 0 T0CON


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Timer 0 ( interrupt example)

/*********************** pic18f2580 **************************\| Testprogram_1 MPlab C18-compiler ||21 juli 2013 J.S.D. Stokkink |+----------------------------------------------------------------------+| USES: TIMER0 , High-interrupt priority | +---------------------------------------------------------------------+| || TIMER0 gives interrupt each 1sec (internal inerrupt)|| De Xtal frequentie is 20MHz | | after each interrupt 1 second a binairy increase on led |\*************************************************************/#include <p18F2580.h>#pragma config OSC = HS // HS oscillator 20 Mhz#pragma config WDT = OFF // Watchdog Timer disabled#pragma config LVP = OFF // Low Voltage ICSP disabled#pragma config PBADEN = OFF // PortB<4:0> configured as digital I/O


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Timer 0 ( interrupt example (2))

// Function-declarations:void InterruptHandlerHigh(void); void InitTimer0(void);void EnableHighInterrupts(void);// Global variables:unsigned int count=0;


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Timer 0 ( interrupt example (3))

#pragma codevoid main (void){ TRISC=0; //led's output PORTC=0; //led off InitTimer0(); EnableHighInterrupts(); // run forever: while(1) {

// do nothing wait on interrupt }}


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Timer 0 ( interrupt example (4))#pragma codevoid InitTimer0(void){

// init timer 0:INTCONbits.GIE = 0; // disable global interruptINTCON2bits.TMR0IP = 1; // Timer 0 high priority interruptRCONbits.IPEN = 1; // enable priority levelsINTCONbits.PEIE = 1; // enable high priority interruptT0CONbits.T0CS = 0; // internal instuction cycle clock (CLKO)T0CONbits.PSA = 0; // prescaler is assignedT0CONbits.T0PS2 = 1; // prescale value bit 2T0CONbits.T0PS1 = 1; // prescale value bit 1T0CONbits.T0PS0 = 1; // prescale value bit 0 ==> 1:256T0CONbits.T08BIT = 0; // 16-bits timerTMR0H = 72; // set timerTMR0L = 229; // set timer ==> ca 1 secINTCONbits.TMR0IE = 1; // Timer 0 interrupt enabledT0CONbits.TMR0ON = 1; // enable Timer 0INTCONbits.GIE = 1; // enable global interrupt

}


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Timer 0 ( interrupt example (5))#pragma codevoid EnableHighInterrupts(void){

RCONbits.IPEN = 1; // enable interrupt priority levelsINTCONbits.GIEH = 1; // enable all high priority iterrupts

} // High priority interrupt vextor:#pragma code high_vector = 0x08void high_interrupt(void){

_asm goto InterruptHandlerHigh _endasm}#pragma code#pragma interrupt InterruptHandlerHighvoid InterruptHandlerHigh(void){

if(INTCONbits.TMR0IF) // check for TMR0 overflow {

INTCONbits.TMR0IF = 0; // clear interrupt flagTMR0H = 72; // reload timerTMR0L = 229; // reload timerPORTC++; // increase value on led }

}


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Assignments lesson 1

1. Make the example working2. Change the programm, let the

counting do every 2 seconds3. Reset the counting on the LED with a RB0 interrupt

saxion university of applied sciences advanced microcontrollers a practical approach

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