Hallo,
Habe ein Problem mit den UART leider muss ich vor jeden Senden 105us
warten da es sonst zu Überschneidungen der Bytes kommt, ich benutze
einen max3232 sowie einen atmega88 auf 20mhz irgend jemand eine Idee
woran es liegen könnte evtl. Fehlerate zu hoch ?
Gruss Rudolf
MAIN
1 | #define F_CPU 20000000UL
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2 |
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3 | #include <stdio.h>
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4 | #include <string.h>
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5 | #include <avr/io.h>
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6 | #include <avr/interrupt.h>
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7 | #include <util/delay.h>
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8 | #include "usart.h"
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9 |
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10 | // Defines
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11 | #define sleep() asm volatile ("nop")
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12 |
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13 | //Prototypen
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14 |
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15 |
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16 | //Hauptprogramm
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17 |
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18 | //Globale Variablen
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19 | uint8_t temp;
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20 |
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21 |
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22 |
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23 | int main (void)
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24 | {
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25 |
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26 | USART0_init();
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27 | USART0_puts((uint8_t *)"Hello\n");
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28 |
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29 | sei(); //irq enable
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30 |
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31 |
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32 | while(1) //hauptschleife
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33 | {
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34 | //casten
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35 | //
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36 | // USART0_write(0x41);
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37 | // USART0_write(0x42);
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38 | // USART0_write(0x43);
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39 | // _delay_ms(1000);
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40 |
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41 | //nix
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42 | }
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43 | // cli(); //int deaktivieren
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44 | return (1);
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45 | }
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46 |
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47 |
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48 | ISR(USART_RX_vect)
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49 | {
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50 | temp = UDR0; //daten vom uart
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51 | USART0_write(temp);
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52 | }
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USART.C
1 | // -------------
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2 | // --- usart ---
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3 | // -------------
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4 |
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5 | #include <avr/io.h>
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6 | #include <avr/interrupt.h>
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7 | #include <util/delay.h>
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8 |
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9 |
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10 | //USART0 TX Complete
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11 | //ISR(USART_TX_vect)
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12 | //{
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13 | //}
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14 |
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15 | //USART0 Data Register Empty
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16 | //ISR(USART_UDRE_vect)
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17 | //{
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18 | //}
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19 |
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20 | void USART0_init()
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21 | {
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22 | // settings: 115200 8-n-1
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23 | // real baud = 119047
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24 | // error = 3.3394097222222197%
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25 | // Set baud rate
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26 | UBRR0H = 0;
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27 | UBRR0L = 20;
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28 | UCSR0A = (1<<U2X0);
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29 | // Enable receiver and transmitter
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30 | UCSR0B = (1<<RXCIE0)|(1<<RXEN0) | (1<<TXEN0);
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31 | // Set frame format
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32 | UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
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33 |
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34 |
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35 | }
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36 |
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37 | void USART0_write(uint8_t data)
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38 | {
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39 | _delay_us(105); //sonst fehler
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40 |
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41 | // Wait for empty transmit buffer
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42 | while ( !( UCSR0A & (1<<UDRE0)) ) ;
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43 | // Put data into buffer, sends the data
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44 | UDR0 = data;
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45 | }
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46 |
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47 | uint8_t USART0_read()
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48 | {
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49 | // Wait for data to be received
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50 | while ( !(UCSR0A & (1<<RXC0)) );
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51 | return UDR0;
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52 | }
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53 |
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54 |
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55 | void USART0_puts(unsigned char *txt)
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56 | {
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57 | while (*txt) USART0_write(*txt++);
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58 | }
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