Hi there,
I'm using the Arduino Uno quite a long time, but since yesterday I can't upload my code anymore.
I tried all the troubleshooting hints and googled for hours, no solution did work (e.g. pressing the reset button after pressing the upload button - I tried it round about 50 times 
).
Using Linux, I receive this message:
hans@hans-desktop:~/jowblobb$ avrdude -F -p atmega328P -P /dev/ttyACM0 -c arduino -b 19200 -vvvv
avrdude: Version 5.10, compiled on Jun 29 2010 at 21:09:48
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2009 Joerg Wunsch
System wide configuration file is "/etc/avrdude.conf"
User configuration file is "/home/flo/.avrduderc"
User configuration file does not exist or is not a regular file, skipping
Using Port : /dev/ttyACM0
Using Programmer : arduino
Overriding Baud Rate : 19200
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude done. Thank you.
Trying to upload it on Windows XP, it says something like
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
I guess I have to burn the bootloader again to fix it.
Here comes the question: This is the code I uploaded last.
Am I doing anything forbidden here?
I'm asking because I've got another Uno Board, but I don't dare to upload it there until I know there's nothing wrong with the code 
(I'm trying to setup a LIN-Bus Slave using RX and TX)
#include <avr/io.h>
#include <stdint.h>
#include <avr/wdt.h>
#include <avr/interrupt.h>
#define VREF 5
#define FOSC 8000000
#define BAUD 9600
#define MYUBRR FOSC/16/BAUD-1
#define WDTO_16msec 0
#define WDTO_32msec 1
#define WDTO_64msec 2
#define WDTO_125msec 3
#define WDTO_250msec 4
#define WDTO_500msec 5
#define WDTO_1sec 6
#define WDTO_2sec 7
#define WDTO_4sec 32
#define WDTO_8sec 33
/* PORTC */
#define PC7 7
#define PC6 6
#define PC5 5
#define PC4 4
#define PC3 3
#define PC2 2
#define PC1 1
#define PC0 0
/* DDRC */
#define DDC7 7
#define DDC6 6
#define DDC5 5
#define DDC4 4
#define DDC3 3
#define DDC2 2
#define DDC1 1
#define DDC0 0
/* PINC */
#define PINC7 7
#define PINC6 6
#define PINC5 5
#define PINC4 4
#define PINC3 3
#define PINC2 2
#define PINC1 1
#define PINC0 0
//------------------------------Globale Variablen------------------------------------
uint8_t Relais_Position=0;
uint8_t Relais_Position1=0;
uint8_t Relais_Position2=0;
int8_t Daten[8];
uint8_t PID;
uint8_t Slave_Address=0;
uint16_t ADC_Val;
int8_t Temperatur1=0;
int8_t Temperatur2=0;
uint8_t Vref=0;
void USART_Init(uint16_t ubrr)
{
// Baudrate setzen
UBRR0H = (uint8_t)(ubrr>>8);
UBRR0L = (uint8_t)ubrr;
// Receiver und Transmitter einschalten UND Transmitt und Receive Interrupts einschalten
UCSR0B = (1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0)|(1<<TXCIE0);
//Frameformat setzen: Asynchron 8 Daten, Keine Parität 1 Stop bit (8N1)
UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
}
//-------------------------------------Sende Zeichen-------------------------------
void Send_Byte(uint8_t sendByte){
DDRC = (1 << DDC2); //grüne LED einschalten (senden)
PORTC |= (1<<PC2);
while (!(UCSR0A & (1<<UDRE0))) //warten bis Senden möglich
;
UDR0 = sendByte; // schreibt das Zeichen auf die Schnittstelle
//DDRC = (1 << DDC2);
PORTC &= (0<<PC2); //grüne LED ausschalten (senden)
}
//-----------------------------Empfange Zeichen-----------------------------------
uint8_t Receive_Byte(){
uint8_t status;
DDRC = (1 << DDC3);
PORTC |= (1<<PC3); //rote LED einschalten (receive)
while (!(UCSR0A & (1<<RXC0))) // warten bis Zeichen verfuegbar
;
status = UCSR0A;
if (status & (1<<FE0)){ //wurde ein Break empfangen?
return 1;
}
else{
return UDR0; // Zeichen aus UDR an Aufrufer zurueckgeben
}
DDRC = (0 << DDC3);
PORTC &= (0<<PC3); //rote LED ausschalten (receive)
}
//-------------------------Parität berechnen------------------------------------
uint8_t Paritaet_Berechnen(uint8_t PID){
uint8_t ID0;
uint8_t ID1;
uint8_t ID2;
uint8_t ID3;
uint8_t ID4;
uint8_t ID5;
uint8_t P0;
uint8_t P1;
uint8_t P0_temp;
uint8_t P1_temp;
P1 = (PID & 10000000) >> 7;
P0 = (PID & 01000000) >> 6;
ID5 = (PID & 00100000) >> 5;
ID4 = (PID & 00010000) >> 4;
ID3 = (PID & 00001000) >> 3;
ID2 = (PID & 00000100) >> 2;
ID1 = (PID & 00000010) >> 1;
ID0 = (PID & 00000001);
P1_temp = ID1^ID3^ID4^ID5;
P0_temp = ID0^ID1^ID2^ID4;
if ((P1==P1_temp) && (P0==P0_temp)){
return 1;
}
else
return -1;
}
//-----------------------Slave Adresse am Port D einlesen---------------------
uint8_t Read_Slave_ADR(){
Slave_Address = PIND;
Slave_Address = (Slave_Address & 11100000) >> 5;
return Slave_Address;
}
//------------------------------------MAIN------------------------------------
void setup(void){
//---------------------------------Initialisierungen------------------------------
USART_Init(MYUBRR);
//-----------------------------------ENDE Init-----------------------------------
sei (); //ab hier werden Interrupts zugelassen
}
void loop (void) {
Send_Byte(5);
delay(1000);
}//ende Main
//-------------------------------------------------------------------------------------------
ISR (USART_RX_vect) { //Die Interupt Service Routine wird ausgeführt wenn ein zeichen empfangen wird
uint16_t TMPchecksum = 0;
uint8_t checksum; //Hier steht die Enhanced Checksumme
uint8_t ID; //Hier steht die vom Master versandte ID (ohne Paritätsbits)
uint8_t PID; //Hier steht die vom Master versandte ID (mit Paritätsbits)
uint8_t ID_adr; //Hier stehen die oberen drei Bits der ID mit der die Baugruppe angesprochen wird
uint8_t ID_func; //Hier stehen die unteren drei Bits der ID mit der die Funktionen ausgeführt werden
uint8_t SyncFeld;
uint8_t Sync_Break;
//LIN KOMMUNIKATION STARTET HIER
Sync_Break=Receive_Byte();
if (Sync_Break){ //Ein Frame Error wird durch ein Sync-Break hervorgerufen
if (SyncFeld==0x55){
PID = Receive_Byte();
ID = (PID & 00111111); //ID (ohne Paritätsbits)
ID_adr = (ID >> 3);
ID_func = (PID & 00000111);
if(Paritaet_Berechnen(PID)) {
if ((ID_func==0) && (Slave_Address==ID_adr)){
// printf("id_func 0)");
/*
for (uint8_t i=0; i<=6; i++){
Send_Byte(Daten[i]); //gesammelte Daten senden
TMPchecksum= TMPchecksum + Daten[i]; //Checksumme berechnen (CARRY-BIT fehlt noch)!!!!!!!
}
TMPchecksum = TMPchecksum+PID; //Enhanced Checksumme!
//Low-Byte der checksumme + High-Byte der checksumme
checksum = (uint8_t) ((TMPchecksum & 0x00FF) + (TMPchecksum >> 8));
checksum= ~checksum; //Checksumme invertieren
Send_Byte(checksum); //anschließend die Checksumme senden
*/
}
if ((ID_func == 1) && (Slave_Address==ID_adr)){
// printf("id_func 1)");
}
if ((ID_func == 2) && (Slave_Address==ID_adr)){
// printf("id_func 2)");
}
if ((ID_func == 3) && (Slave_Address==ID_adr)){
// printf("id_func 3)");
}
if ((ID_func == 4) && (Slave_Address==ID_adr)){
// printf("id_func 4)");
}
if ((ID_func == 5) && (Slave_Address==ID_adr)){
// printf("id_func 5)");
}
if ((ID_func == 6) && (Slave_Address==ID_adr)){
// printf("id_func 6)");
}
if ((ID_func == 7) && (Slave_Address==ID_adr)){
// printf("id_func 7)");
}
}//parität
else{
DDRC = (1 << DDC4);
PORTC |= (1<<PC4);
} //gelbe LED eischalten, somit liegt ein Paritätsfehler vor
}//syncfeld
}//FE
}//ISR
This is just the first draft, so I know the code is far away from being perfect
Cheers!
