Labs‘Codes review(AVR)（3）

Example 1：Set bit 5 of port B to be an output and other bits to be inputs

Assembly language

复制代码

ldi r16,(1<<5);
out DDRB,r16;

C equivalent

复制代码

DDRB=(1<<5);

Example 2：Set bits 3 and 4 of port B to be outputs whilst keeping the direction of the other bits the same

Assembly language

复制代码

ldi r16,(1<<3)|(1<<4);
out DDRB,r16;

C equivalent

复制代码

DDRB=(1<<3)|(1<<4)

3.output values 10 to 15 as hex digits

复制代码

#include <avr/io.h>

uint8_t seven_seg[10] = { 63,6,91,79,102,109,125,7,127,111};

int main(void) {
    uint8_t digit;
    
    /* Set port A pins to be outputs, port C pins to be inputs */
    DDRA = 0xFF;
    DDRC = 0;    /* This is the default, could omit. */
    while(1) {
        /* Read in a digit from lower half of port C pins */
        /* We read the whole byte and mask out upper bits */
        digit = PINC & 0x0F;
        /* Write out seven segment display value to port A */
        if(digit < 10) {
            PORTA = seven_seg[digit];
        } else {
            PORTA = 0;
        }
    }
}

4.Modify the task 1 code so that your program can also output values 10 to 15 as hex digits

复制代码

#include <avr/io.h>

uint8_t seven_seg[16] = { 63,6,91,79,102,109,125,7,127,111,119,124,57,94,121,113};

int main(void) {
    uint8_t digit;
    DDRA = 0xFF;
    DDRC = 0;    
    while(1) {
        digit = PINC & 0x0F;
        if(digit < 16) {
            PORTA = seven_seg[digit];
        } else {
            PORTA = 0;
        }
    }
}

Modify the code in Task 2 so that your program also outputs the digit (in binary) on AVR port B. Connect the lower 4 bits of port B to 4 LEDs

#include <avr/io.h>

uint8_t seven_seg[16] = { 63,6,91,79,102,109,125,7,127,111,119,124,57,94,121,113};

int main(void) {
uint8_t digit;
DDRA = 0xFF;
DDRB = 0xFF;
DDRC = 0;
while(1) {
digit = PINC & 0x0F;
PORTB = digit;
PORTA = seven_seg[digit];
}
}

5.Write a program that repeatedly reads the lower 4 bits of port A and the lower 4 bits of port B and adds these two values together and displays (on the SSD, using a port of your choice) the hexadecimal value of the lower 4 bits of the result

复制代码

#include <avr/io.h>

uint8_t seven_seg[16] = { 63,6,91,79,102,109,125,7,127,111,119,124,57,94,121,113};

int main(void) {
	uint8_t a, b, c;
	DDRA=0x00;
	DDRB=0x00;
	DDRC=0XFF;
	
	while(1) {
		a=PINA&0x0F;
		b=PINB&0x0F;
		c=a+b;
		PORTC=seven_seg[c&0x0F];
	}
}