Hello,
I've problems with the printf() routine. I receive frames over the ethernet in a very short intervall. If I received a frame I set a flag in the ISR.
void ethernet_interrupt(void) __irq { unsigned int status; AT91PS_EMAC pEmac = AT91C_BASE_EMAC; status = pEmac->EMAC_ISR; if (status & AT91C_EMAC_RCOM) /* Receive complete */ Emac_Receive++; // clear receive status register pEmac->EMAC_RSR &= ~(AT91C_EMAC_OVR | AT91C_EMAC_REC | AT91C_EMAC_BNA); AT91C_BASE_AIC->AIC_EOICR = 0; /* End of ISR */ }
In the main routine I ask if the flag is set -> if it is set, I use printf() to see via the usart that I get a new frame...
printf("h");
The problem is that I always get a data abort within the printf() routine..
Could it be that the ethernet frames came to close together (in a short time) so that the printf() routine has not finish to transmit the last character?
And after the ISR the printf() routine don't know what to do / what to send -> data abort??
If the printf-argument is much bigger - it is often so that I only can transmit one or two letter - but not the whole word...
e.g.
printf("hello world\n");
I only transmit "hel" - that's all...
best regards Johannes
Insert a check in the COM1_1_sendchar() function to verify the pointer. If not as expected, insert a dummy instruction and place a breakpoint on it.
You are most probably accessing unaligned or nonexisting memory, or trying to write within your flash address space.
I installed a variable i and insert a dummy instruction.
Which register show me if I use nonexisting memory?
R14(LR) = 0x10000890
I have a external flash memory (16MB) from the base address 0x10000000.
Just write something like:
if (COM1_1 != AT91C_BASE_US1) { dummy_instruction; }
And then set a breakpoint inside the if statement. If something has overwritten the COM1_1 pointer, then the debugger will stop at the breakpoint - before the data abort trap happens.
now I wrote:
int COM1_1_sendchar(int ch) { unsigned int i=0; if (ch == '\n') { /* Check for CR */ while (!(COM1_1->US_CSR & AT91C_US_TXRDY)); /* Wait for Empty Tx Buffer */ COM1_1->US_THR = '\r'; if (COM1_1 != AT91C_BASE_US1) { i++; } } while (!(COM1_1->US_CSR & AT91C_US_TXRDY)); /* Wait for Empty Tx Buffer */ return (COM1_1->US_THR = ch); /* Transmit Character */ }
But the if-statement is never true - so I still have a data abort but the breakpoint (i++) was never reached.
Johannes
Didn't you show the failure point a couple of lines before the point where you added the test?
Do you think you should test if the pointer is valid before - or after - the point where you know that your application fails?
What do you think your probabilities are of reaching this if statement, if the application has already failed?
code:
init_usart(); init_timer(); init_ethernet(); printf("ethernet init done\n"); //<- works
while(1) { if(Emac_Receive >=1) // flag-bit set in ISR ethernet { printf("new frame\n"); //<- problem
Emac_Receive--; } }