1 | #include <stdio.h>
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2 | #include <stdlib.h>
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3 | #include <avr\io.h>
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4 | #include <avr/interrupt.h> //for the interupts for receiving via UART
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5 | #include <string.h> //for building strings of characters
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6 | #include <avr/pgmspace.h> //for PSTR for handling the location of characters
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7 |
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8 | //Set the baud rate of the communication
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9 |
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10 | #define BAUD 9600UL // Baudrate
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11 |
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12 | // Berechnungen
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13 | #define UBRR_VAL ((F_CPU+BAUD*8)/(BAUD*16)-1) // clever runden
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14 | #define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1))) // Reale Baudrate
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15 | #define BAUD_ERROR ((BAUD_REAL*1000)/BAUD) // Fehler in Promille, 1000 = kein Fehler.
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16 |
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17 | #if ((BAUD_ERROR<990) || (BAUD_ERROR>1010))
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18 | #error Systematischer Fehler der Baudrate grösser 1% und damit zu hoch!
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19 | #endif
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20 |
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21 |
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22 | //Four variables for buffering of received messages
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23 | volatile char c; //The temp place to dump the character we just received
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24 | volatile char buffer[30]; // The array holding the characters that have been sent
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25 | volatile int bufferlocation; //The current location in the buffer
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26 | volatile int bufferflag; //A flag to tell whether there is complete data in the buffer to be processed
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27 |
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28 | //Declare the location of the stream for the output
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29 | void uart_printchar(char c, FILE *stream){
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30 | // Wait until UDR ready
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31 | while(!(UCSR0A & (1 << UDRE0)));
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32 | UDR0 = c; // send character
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33 | }
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34 |
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35 | //USART RX interrupt this code is executed when we recieve a character
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36 | ISR(USART0_RX_vect){
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37 | c = UDR0; //Read the value out of the UART buffer
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38 | buffer[bufferlocation] = c; //Dump that value out into the buffer array
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39 | bufferlocation++; //Increment the bufferlocation so its ready to write next time
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40 |
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41 | if (c == 13) //Number 13 is carrage return
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42 | bufferflag = 1; //If its a carriage return then mark the string as ready to process
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43 | }
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44 |
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45 | int BaudRateRegister;
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46 |
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47 | int main(void){
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48 | //---------------Start of Initalisation---------------
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49 |
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50 | //Configure the UART registers
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51 | UCSR0B = ((1<<RXCIE0)|(1<<RXEN0)|(1<<TXEN0));
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52 | //RXCIE0 Enable interupt after recieved
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53 | //RXEN0 Reciever enabled
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54 | //TXEN0 Transmit enabled
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55 |
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56 | UCSR0C = ((1<<UCSZ00)|(1<<UCSZ01));
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57 | //UCSZ00 and UCSZ01 use 8 bit character size
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58 |
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59 | //Set the baud rate
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60 | BaudRateRegister=F_CPU/16/BAUD-1;
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61 | UBRR0H=((BaudRateRegister>>8)&0x00FF);
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62 | UBRR0L=(BaudRateRegister&0x00FF);
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63 |
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64 | //Define and initialise stream used for printing to uart
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65 | FILE uart_str = FDEV_SETUP_STREAM(uart_printchar, NULL, _FDEV_SETUP_RW);
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66 |
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67 | //Redirect stdout, so that printf() knows where to go
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68 | stdout = &uart_str;
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69 |
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70 | //Enable interrupts
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71 | sei();
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72 | //---------------End of Initalisation---------------
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73 | printf_P(PSTR("..."));
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74 | printf_P(PSTR("Running"));
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75 | printf_P(PSTR("BaudRateRegister set to %u\n"),BaudRateRegister);
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76 | printf_P(PSTR("Wait"));
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77 | //Start of infinate while loop
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78 | while(1){
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79 | if (bufferflag == 1){
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80 | printf_P(PSTR("Got instruction"));
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81 | bufferflag = 0; //Reset the buffer flag to say its been processed
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82 | bufferlocation =0; //Restart the buffer location
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83 | }
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84 | }
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85 | //End of infinate while loop
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86 |
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87 | }
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88 | //End of main routine
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