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de:examples:digi:7seg [2009/04/27 18:16] – angelegt nierhoffde:examples:digi:7seg [2020/07/20 12:00] (current) – external edit 127.0.0.1
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 +====== 7-Segment-Anzeige ======
 +
 +{{:examples:7-seg.jpg|}}
 +
 +Das Study Board ist meiner einer 7-Segment LED Anzeige und dem entsprechendem Treiber (A6275) ausgestattet.
 +({{:examples:datasheets:a6275_led_driver.pdf|datasheet}}).
 +Der Treiber ist an PORT-C und PORT-G des Controllers angeschlossen.
 +
 +Der Schaltplan zeigt: Das Auffangregister (latch) liegt an PORT-G2, Serial an PORT-C6 und Clock an PORT-C7.
 +
 +{{:examples:7seg_schematics.jpg?500}}
 +
 +
 +===== Beispiel 1 =====
 +
 +<code c>
 +/* 
 +Basic ver 3 demo program
 +7-seg function and demo
 +Raivo Sell/Erki Leitaru
 +*/
 +#define F_CPU 14745600UL
 +
 +#include <avr/io.h>
 +#include <util/delay.h>
 +
 +#define SET(x) |= (1<<x)  //defineeritakse kõrge bit pordis x
 +#define CLR(x) &=~(1<<x)  //defineeritakse madal bit pordis x
 +#define bit_get(p,m) ((p) & (m)) //returns 1 if bit is set, otherwise returns 0
 +#define BIT(x) (0x01 << (x))
 +
 +void write_display (void);
 +void nop_delay(int count);
 +
 +int i;//for cycle
 +int digit;//digit to display on segment
 +int nr;//segment map representation of the digit
 +int delta;//to create a counting effect
 +int num = 0;
 +char buffer[7];
 +
 +void nop_delay(int count){
 + unsigned int j;
 + for (j=0; j<count;j++) {asm volatile ("nop");}
 +}
 +
 +void write_display (void) {
 + switch (digit) //table read to get segment map representation of the digit
 + {
 + case 0 : nr = 0b00111111;break; //every bit corresponds to one segment
 + case 1 : nr = 0b00000110;break; //"1"
 + case 2 : nr = 0b01011011;break; //"2" and so on
 + case 3 : nr = 0b01001111;break; 
 + case 4 : nr = 0b01100110;break; 
 + case 5 : nr = 0b01101101;break; 
 + case 6 : nr = 0b01111100;break; 
 + case 7 : nr = 0b00000111;break;
 + case 8 : nr = 0b01111111;break; 
 + case 9 : nr = 0b01100111;break;  
 + default: nr = 0b01111001;//E
 + }
 +
 + PORTG CLR (2); //latch low
 + for(i=7; i>=0; i--) //for every bit in the byte
 + {
 + //if bit is set, sets the data out pin
 + if (bit_get(nr, BIT(i))) PORTC SET (6); //serial out
 + else PORTC CLR (6); //serial out
 +
 + PORTC SET (7); //clock high
 + nop_delay(8);//series of one cycle delays to ensure required timing (according to datasheet)
 +
 + PORTC CLR (7); //clock low
 + nop_delay(8);
 + }
 + PORTG SET (2); //latch high
 +
 +}
 +
 +int main(void){
 +
 + //7-seg init
 +    PORTC = 0xFF; // set output high -> turn all LEDs off
 +    DDRC  = 0xF8; // PC0...PC2 -> input; PC3...PC5 -> output for LED; PC7 & PC6 outputs for clock and data
 + DDRG  = 0x04;//PG2 is latch output
 +
 + digit = 8;
 + delta = 1;//increment or decrement
 +
 + while(1) {
 + num++;
 + _delay_ms(1000);
 + digit=digit+delta;//change digit by delta
 + if(digit>8) {delta=-1*delta;};//upper limit
 + if(digit<1) {delta=-1*delta;};//lower limit
 + write_display();
 + }
 +}
 +
 +</code>
 +
 +===== Beispiel 2 =====
 +
 +Dieses Bsp. nutzt die Header Datei pin.h für Pin-Operationen [[en:examples:digi:pin|"pin.h"]]
 +
 +<code c>
 +//
 +// Simple up/down counting single 7-segment digit example.
 +//
 +// Raivo Sell, Erki Leitaru, Mikk Leini
 +//
 +// 2009
 +//
 +
 +// Include avrlibc
 +#include <avr/io.h>
 +#include <util/delay.h>
 +
 +// Include common library
 +#include "pin.h"
 + 
 +// Configure pins
 +#define SEGMENT_DISPLAY_LATCH      PORTPIN(G, 2)
 +#define SEGMENT_DISPLAY_DATA_OUT   PORTPIN(C, 6)
 +#define SEGMENT_DISPLAY_CLOCK      PORTPIN(C, 7)
 +
 +//
 +// 7 segment display initialization
 +//
 +void segment_display_init(void)
 +{
 + // Set latch, data out and clock pins as output
 + pin_setup_output(SEGMENT_DISPLAY_LATCH);
 + pin_setup_output(SEGMENT_DISPLAY_DATA_OUT);
 + pin_setup_output(SEGMENT_DISPLAY_CLOCK);
 +}
 +
 +//
 +// Digit writing to 7 segment display
 +//
 +void segment_display_write(unsigned char digit)
 +{
 + unsigned char map;
 +
 + // Decimal to segment map
 + switch (digit)
 + {
 + case 0 : map = 0b00111111; break; // Every bit corresponds to one segment
 + case 1 : map = 0b00000110; break; // "1"
 + case 2 : map = 0b01011011; break; // "2"
 + case 3 : map = 0b01001111; break; // "3" and so on
 + case 4 : map = 0b01100110; break; 
 + case 5 : map = 0b01101101; break; 
 + case 6 : map = 0b01111100; break; 
 + case 7 : map = 0b00000111; break;
 + case 8 : map = 0b01111111; break; 
 + case 9 : map = 0b01100111; break;  
 + default: map = 0b01111001;        // E like Error
 + }
 +
 + // Latch low
 + pin_clear(SEGMENT_DISPLAY_LATCH);
 +
 + // Send every bit in the byte. MSB (most significant bit) first.
 + for (signed char i = 7; i >= 0; i--)
 + {
 + // If bit is set, sets the data out pin, otherwise not
 + pin_set_to(SEGMENT_DISPLAY_DATA_OUT, IS_BIT_SET(map, i));
 +
 + // Clock high for certain period
 + pin_set(SEGMENT_DISPLAY_CLOCK)
 + _delay_us(1);
 +
 + // Clock low for certain period
 + pin_clear(SEGMENT_DISPLAY_CLOCK)
 + _delay_us(1);
 + }
 +
 + // Latch high
 + pin_set(SEGMENT_DISPLAY_LATCH);
 +}
 +
 +//
 +// Program entrance function
 +//
 +int main(void)
 +{ 
 + unsigned char digit = 0; // Digit to display on segment
 + signed char delta = 1;   // Digit modifying value
 +
 + //digit = int (void) { return 2; }; 
 +
 + // 7 segment display initialization
 + segment_display_init();  
 + 
 +  // Endless loop
 + while (1)
 + {
 + // Write digit
 + segment_display_write(digit);
 +
 + // Increase digit value by delta (which can be negative also)
 + digit += delta;
 +
 + // Swap counting direction on 0 and 9
 + if (digit == 0) delta = +1;
 + if (digit == 9) delta = -1;
 +
 + // Wait 1000 ms
 + _delay_ms(1000);
 + }
 +}
 +</code>
 +
 +===== Externe Links =====
 +[[http://en.wikipedia.org/wiki/Seven-segment_display|7-segment display in Wikipedia]]
  
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