Hi all.
I am working in avr studio 4. Many times I suffer for this problem and I don't know what is happening. Many times when i make a code at some point it jumps to some invalid location / some invalid infinite loop. So here i create one example of code which can give you idea.
#include#ifndef F_CPU #define F_CPU 8000000UL #endif #include #include #include #include #include void usart_timer_init (unsigned int uintBaudRate,unsigned char ucharParity,unsigned char ucharStopbit); //USART Timer INITIALIZATION Function unsigned char uchararryDataString[20]; unsigned char ucharStringIndex=0; unsigned char ucharStringFullFlag=0; unsigned char ucharTimerCount; int main(void) { DDRA=0x00; usart_timer_init(9600,0,0); sei(); PORTA=0xFF; while(1) { while(1) { if (ucharStringFullFlag!=0) break; } PORTA=~PORTA; } } void usart_timer_init (unsigned int uintBaudRate,unsigned char ucharParity,unsigned char ucharStopbit) //USART INITIALIZATION Function { //Define uintBuadRate as values like 4800,9600 //Define ucharParity as values like: // For none parity 0 // For even parity 2 // For odd parity 3 // (if supplied any other value it will take initial values) //Define ucharStopbit as values like // For one bit 0 // For two bit 1 // (if supplied any other value it will take initial values) unsigned int uintUBRR; uintUBRR = (F_CPU/uintBaudRate/16)-1; if (ucharParity != 0 && ucharParity != 2 && ucharParity != 3) ucharParity = 0; if (ucharStopbit != 0 && ucharStopbit != 1) ucharStopbit = 0; // For Atmega8515 UBRRH = (unsigned char)(uintUBRR>>8); UBRRL = (unsigned char)uintUBRR; UCSRB = (1<<RXCIE)|(1<<RXEN)|(1<<TXEN); //RX interrupt Enable //RX enable //TX enable UCSRC = (1<<URSEL)|((ucharParity<<4) & 0x30)|((ucharStopbit<<3) & 0x08)|0x06; // define Asynchronous Mode // parity bit and stop bit character size //-------- timer settings------------------------------- //Timer 0 is used to generate 1.5 character delay. If communication lines are idle for more //then this time it will flush RX input buffer. Please check your system does not using timer0 ucharTimerCount=((F_CPU/1000)*64)/uintBaudRate; TIMSK|=0x02; //TIMER0 INTERRUPT ENABLE TCNT0=ucharTimerCount; //Timer delay for 1.5 character wait } SIGNAL(USART_RX_vect) //ATmega8515 { unsigned char ucharRX_data; // RX buffer reg ucharRX_data = UDR;//store valid data in Rx buffer register if (ucharRX_data==0x05) { TCNT0= ucharTimerCount; // Reload count at every successful reception TCCR0=0x04; // turn on timer with prescaler of 256 ucharStringFullFlag=1; } else TCCR0=0x00; // turn off timer uchararryDataString[ucharStringIndex++]=ucharRX_data; }//serial USART interrupt end here //#################################################################### //#################################################################### //Timer 0 overflow Interrupt ISR used for 1.5 character delay ISR(TIMER0_OVF_vect) { ucharStringIndex=0; TCCR0=0x00; // turn off timer }//Timer 0 overflow interrupt end here
In this code if you debug you can see it goes into infinite loop @ below statement even if interrupt and timer overflows occur regularly.
if (ucharStringFullFlag!=0) break;
When i build and run into avr simulator and i found this in disassembler window:
+00000061: BA1A OUT 0x1A,R1 Out to I/O location 27: usart_timer_init(9600,0,0); +00000062: E880 LDI R24,0x80 Load immediate +00000063: E295 LDI R25,0x25 Load immediate +00000064: E060 LDI R22,0x00 Load immediate +00000065: E040 LDI R20,0x00 Load immediate +00000066: DFBB RCALL PC-0x0044 Relative call subroutine 28: sei(); +00000067: 9478 SEI Global Interrupt Enable 29: PORTA=0xFF; +00000068: EF8F SER R24 Set Register +00000069: BB8B OUT 0x1B,R24 Out to I/O location 35: if (ucharStringFullFlag!=0) +0000006A: 91900061 LDS R25,0x0061 Load direct from data space +0000006C: 2399 TST R25 Test for Zero or Minus +0000006D: F021 BREQ PC+0x05 Branch if equal 39: PORTA=~PORTA; +0000006E: B38B IN R24,0x1B In from I/O location +0000006F: 9580 LAT R24 Load and Toggle +00000070: BB8B OUT 0x1B,R24 Out to I/O location +00000071: CFFA RJMP PC-0x0005 Relative jump +00000072: CFFF RJMP PC-0x0000 Relative jump
so even if interrupt is there, portA will never toggle.
Herewith I am attaching zip file of my project in avr studio 4.18, WinAVR - 20100110.
This is one example. But many times i have suffered due to this kind of problems (every time i have to go through avr simulator's disassembler). I don't know if this is C why it is not working as i program. Is there any point missing in my code? Please help me. When i do long application based code this becomes headache. Thanks in advance
