Thread: Micro-controller programming basics.

Hi - I'm trying to get to grips with programming micro-controllers using c before I go to Uni next year. I'm doing a view tasks on the internet and have written a program to simply turn an led on and off as a biased switch is pressed. I was wondering how I could write a similar program to transfer the state of the lower 5 dil switches (RC0 to RC4) to LEDs (RA0 to RA4) without allowing RC5 to affect anything.




/*
A program that causes an LED, connected to RA0,
to go on and off as the biased switch,
connected to RC6, is closed and opened.
All other LEDs (connected to RA1 to RA4) and the buzzer (RA5)
should be off.
/*

#include <p18f2221.h>
#pragma config OSC=HS /* 0.4us cycle time with 10MHz osc */
#pragma config WDT=OFF
#define Switch PORTCbits.RC6
#define LED PORTAbits.RA0 void main(void){
ADCON1=0x0f; /* digital IO */
TRISA=0xc0; /* 6 LEDs as outputs */
TRISC=0xff; /* PORTC as inputs */
PORTA=0x00; /* all LEDs off */
while(1){ /* forever */
if(Switch) /* is switch open (non zero)*/
LED=0;

else
LED=1; /* turn LED on */
}
}

Any of your help and time would be much appreciated.

While most of us here are happy to give you a hand with the C language aspects of what you're doing, this is not a microcontroller support site. I'm thinking you will get a lot better information and support by going to the forums or mailing lists connected with your particular development board...

Ok thanks - I'll try there

If your compiler does not allow defining a variable to access a single bit (it appears that your compiler might) then you will need to use bit masking with the logical operators to alter a single bit in a byte. See this link for an small tutorial.

Jim

depending which micro you have the code would be even simpler, for instance the micro i do all my programing with is the PSoC programmable system on chip and the languages are c or assemble but to just simply turn on an led and turn off, i would just name two ports, one switch and one led

the code would just simply be

if(switch_Data_ADDR & switch_MASK)
{ LED _DATA_ADDR ^= LED_MASK

this would just combine all 8 bits of what ever data registry you had, and the exclusive or would detect the high to low transition of the clock and turn on and off the led every time the switch is pressed

depending which micro you have the code would be even simpler, for instance the micro i do all my programing with is the PSoC programmable system on chip and the languages are c or assemble but to just simply turn on an led and turn off, i would just name two ports, one switch and one led

the code would just simply be

if(switch_Data_ADDR & switch_MASK)
{ LED _DATA_ADDR ^= LED_MASK

this would just combine all 8 bits of what ever data registry you had, and the exclusive or would detect the high to low transition of the clock and turn on and off the led every time the switch is pressed